Calculating ROI on a Home Solar Battery
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- เผยแพร่เมื่อ 2 ก.ค. 2024
- A follow up to my previous two videos on batteries. This one has been asked for by many people - how to calculate if a particular battery is actually worth it...
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5 Reasons To Get A (Bigger) Home Battery video:
• 5 Reasons To Get A (Bi...
Chapters:
0:00 Intro
1:31 Main factors to consider: Cost, Lifetime, Warranty, Degradation
4:17 Cost per kWh
5:02 "Under Warranty" Formula
7:11 "Run It Into The Ground" Formula
8:32 Get Rich Quick Scheme?
10:26 7 Profitable Actions
13:49 Solarazma Pro Utility
14:40 Summary
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#home #battery #roi - แนวปฏิบัติและการใช้ชีวิต
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We live in Spain and in 2020 we put in (self install) a 6kW array with 20kWh of pylontech batteries along with a hybrid inverter. Total cost was ~9000 Euros. In the 3 years since we've saved about 4 grand in electric bills so are a little under 50% of the way to break even, however the savings are more prominent now than at the start so in reality our break even will probably be in a couple of years from now. However far more importantly we have not had to suffer a single one of the many power outages since nor do we have to care about the ridiculous 3 tier tarrifs they have here which essentially mean most people have to do any heavy power use in the early morning hours.
In other words, there's more than just the money there's the quality of life being partially independent of the crazy world we live in now brings
Wow - that's a fantastic saving, and you're right, there are many reasons people for for solar and battery, including the ones you stated. I do know though that the high costs are an issue for many, and so careful calculations are necessary to avoid disappointment later on...
Prices on the continent are half the price of Ireland plus dont get quarter the sun you would so payback is 4-5 times the payback. People in northern europe should nearly sponsor someone in spain to get an install rather than using it for a few months a year the further north you go. 🤣
@@davidfarrell1062 Not a bad idea! 😃
@@davidfarrell1062Prices here are lower because of subsidies. Up until 2019 we had the "sun tax" here which meant you had to PAY iberdrola (the power company) for producing your own power! You didnt get a feed in payment you got a bill for giving them your electricity. Lovely. Hence solar uptake was very low.
Fortunately that little gem was repealed and now the gov are keen to get everyone into self generation so prices have plummeted.
This must take a lot of effort to put together Gary, clear and concise information again. Well done 👏🏼
Thanks Oliver - yeah, this video was 3 full days effort in total. I really need to find ways to cut down that time! Glad you found it useful :-)
Hi Gary, I just discovered your channel today, what fantastic content, very clear explanations which will be of immense benefit to many people. I have just signed up to Patreon to help you continue your great work and this is my first time using Patreon. Over the next year, I plan to build a home solar system and yours is my go to channel to help me design it👍
Hi Mark, thanks very much for these very kind words - they made my day! And you joining my Patreon was the icing on the cake - thank you! :-) Feel free to message me anytime on Patreon if you have any questions regarding your planned solar installation - all the best with it!
Thanks very much Gary for your offer of help, much appreciated 👍 I will be having a good think about what I want the system to do over the Xmas break then digging into the details.
One of the most comprehensive videos talking about batteries ROI (or more accurately LOI... Loss On Invest 🤑). Congratulations for this video... and for your TH-cam channel in general 👍
Thanks very much for your kind words about the video and also my channel. Agreed, we need to find ways to turn that LOI into ROI - and with battery prices coming down all the time, I think we will :-)
Another excellent and informative video - thank you Gary.
I installed my solar PV and home battery system just over 2 years ago and to date I've adopted a fairly simplistic approach. During the high generation months (April to October) I use solar from my 5.6kWp array to:
1 - Power my home
2 - Re-charge my 10.2kW capacity home batteries to 100%
3 - Charge my EV when possible (min solar excess of 1.4kW required by my Zappi charger)
4 - Export any excess to the grid (I'm with Octopus, so get 15p/kW for export)
I'm currently on an Economy 7 tariff, so get 7 hours of cheaper electricity at night. During the low generation months (November to March) I charge my home batteries to 100% each night using the cheaper rate electricity. I also charge my EV when required. Charging my home batteries to full allows me to use energy from the batteries during the day as required to power my home. In practice I've found I don't have quite enough battery capacity to power my home completely in the depths of winter, so I'm about to install a third battery, increasing my capacity to 15.3kW.
My home batteries can also provide an amount of power to my home in the event of a grid power cut. There are limits to which circuits I can use of course, based on the maximum discharge rate of my batteries, but it's a useful benefit to have.
This all sounds great. Thanks for sharing - it will be of help to others 👍🏻
Hi
I’m considering an EV and charger. I already have solar and battery storage. Do you charge your home battery then your EV via your battery or does your battery charge and then switch to the EV bypassing the battery ( hope that makes sense)
I have similar situation to @dalroth above, but have an EV. The issue with EV charging is that the total inverter output is 5kW, so my EV draws 7kW and even on a blazing sunny day with 5kW coming from the panels, I am paying 2kWh peak rate on top! It's a complicated sum to work out how this compares with simply charging off peak and selling all surplus at 15p to Octopus. Only solution I can see is if you haven't already bought your EV charger, (which we had a couple of years ago), buy a Zappi as it is capable of trimming the charge to your EV at 5kW. The ROI business case for swapping a non-defective EV charger for a Zappi is a non-starter, but if you are setting up from scratch, a Zappi is probably the way to go in my opinion. 😊
@@rowansmith2411 I have a Zappi.... but no EV yet 🤣 One day...
And like you, I'm restricted to 5kW through my GivEnergy inverter. I do like it that the Zappi can dial down to what solar there is, but I guess overall, charging at 7kW during a cheap off-peak rate is the way t go in general...
Yet another excellent and very polished video Gary!
Thanks :-) I really appreciate the feedback!
Very clear way of looking at the battery option from a financial viewpoint. Thanks.
You're most welcome and thanks for the great feedback! :-)
Very useful Gary. I did a simplistic calc on my solar and battery and came out with similar figures for battery payback. That was reassuring. My simple model was charge at night and use in day all year round then export all solar. Not actually what we do but it was a way of separating solar and battery in the calc. Economy 7 tariff (best for our situation) and 15p kWh for export. Cheers Paul
You're most welcome, Paul - thanks for letting me know!
Very good info Gary awesome data ,I needed that
Thanks - you’re most welcome 👍🏻😀
Thanks for all the videos Gary!
I used your referral link for Octopus to give back to yourself! soon to have solar installed
You're most welcome, and thank you for thinking of me with the referral code. That means a lot! :-)
Before I get to the point, which is a strategy with the Octopus Flux tariff, having Solar panels installed in the Autumn is depressing as, until Spring, the output from the panels is so low!
As viewers of Gary's videos will be aware, Flux has three rates for Import and Export each day. I gradually increased my import during the Cheap period from 40% to 100% SoC for my 5kW battery, i.e. Full.
Exporting at Day rate appeared to be almost identical in price to Importing at Cheap rate. However, taking Value Added Tax (VAT) into account it's actually a loser😞
I'm now trying to determine how much to import during the Cheap period so that I'm not exporting during the Day rate periods, but do have enough stored to cover evening use.
Thanks for the 7 different situations near the end of the video, with their pictograms, Gary🙂
Thanks Robert - this is great insight. I'm coming to similar conclusions re. Flux myself - and I'm hoping to explain everything in the next video, which is on strategies for smart tariffs... It turns out to be a lot more involved than I'd expected!
Hi Gary
Another side of this story was highlighted in a piece by Andrew Orlowski in today's Daily Telegraph (p 18) drawing attention to the growing energy gap which will emerge in UK over the next few years.
Increasing the number of small domestic solar and battery installations will provide a very much needed buffer to the National grid and help to plug the gap in electricity generation.
I have suggested to Ministers that if building regulations were amended to require all new houses and flats to be equipped with as much solar generation as their roofs could provide and appropriately sized batteries as well as requiring all new industrial and commercial buildings and any converted or improved to do the same then pressure on the grid could be markedly reduced and, by decentralising generation, the need for massive upgrading of local distribution networks could be reduced or even abolished. Response is awaited!
Good luck!
@@David-bl1bt I am not holding my breath. Probably too simple an idea with limited potential for HMG to claim it as a success for its policy. I think it could work and could be implemented by regulation changes at short notice.
Unfortunately a lot of party donating interests would be losing a lot of profits…….
Not sure about that Simon. The generating capacity that is predicted to be required and distributed is not likely to be available centrally for many years, if ever. Generating and supply companies are making good profits and these will be even greater when windfall taxes come to an end. The enormous investment that would be required to meet predicted requirements will impact on future profits so the big players might be very happy to continue to provide for core requirements using existing, or modestly increased, capital plant.
You might remember that some years ago an American electricity generator, near NY I think, gave all its subscribers free low energy bulbs on the basis that the reduction in demand would obviate the need to build a new power station which would have cost a lot more.
Lots of ways to skin a cat!
@@michaelblackmore883 But in an idealised world where everyone has solar, batteries and maybe joint ownership of wind farms and large scale storage there would be greatly reduced need for centralised generation. I am all for this and already a long way down that road.
Thanks Gary. Excellent video. I’ve been working on the same challenge of ROI and I like the way you are heading with the £/kw unit to simplify the approach.
The conclusion that I have come to is that to make either or both solar and battery systems to have a positive ROI outcome is to have a) large solar array 6kw+ and b)cost delta between import/generation and usage/export of around 25-30p/kw.
As cost of systems come down and installation is simplified I.e. cheaper, I can see this becoming more accessible.
You rightly mentioned the changing landscape in the way UK energy market is pricing electricity. Octopus is great but you don’t know what’s coming out next month, let along what’s going to happen during the lifetime of the system. And as such, for now, I’m holding onto my money and wait and see how this evolves in the next 12 months.
As a final note, want to thank you for your modelling tool which I used extensively to get to my personal conclusions. I will continue to subscribe to this channel and to your Patreon as a way to keep up to date with all that’s happening. 👍🏼 keep up the good work.
Hi Kaz, thanks for your very kind words. I agree with all your notes, and I'm hoping (this week even) to add in the battery ROI calculations from the video into Solarazma Pro :-)
Just been having a chat with someone today on a similar subject, great to see us coming down on similar outcomes. One thing i don't think people are clued up on enough (myself before i started this journey down the solar rabbit hole) is battery charge and discharge rates, so might be worth a video on that. I think people think they can just store all the power they are making at any given time.... alas that may not be the case if the sun is full blast, nor can you run everything just because you have a full battery
Hi Ste - yeah, you're right - there are just too many variables with solar and battery installations that making the right purchase decisions is not at all easy. For the charging and discharging, you might like this video I made, which covers those factors: th-cam.com/video/x83t1iCMXxw/w-d-xo.html
On its own a battery is definitely harder to make a return on investment from, but when attached to solar or as a way to offset other energy (e.g heat pump instead of gas/oil boiler, induction hob rather than gas) it makes all the investments together more cost effective.
These calculations get very complex fast, but the simple view is a battery is best a part of a wider strategy to electrify, and ideally with solar as a primary energy source.
By the time your battery is big enough to supply a load for any length of time, charge/discharge rates for a battery are generally not a limitation.
Thanks Gary, another clear and comprehensive video. If you have solar then having a battery is still a must-have because it brings so much more flexibility to using the generated PV than it all going to the grid and then you importing more later on. And given that batteries are usually cheaper the bigger you buy and the (generally fixed) installation gets spread over the larger capacity, its better to buy say 10kW than say 2kw.
One other essential factor to consider is inverter throughput rate and length of the cheap (or peak) charge/discharge period. My GivEnergy gen 1 inverters for example are 2.6kW max throughput so in an overnight 3 hour period I could only charge 7.8kW and that assumes I didn’t have any existing batteries.
I have looked several times at adding further battery storage to my solar array and depending on the usage scenarios I adopt I have an ROI of 24+ years! Just not worth it unless battery tech comes down significantly in price or electricity tariffs shoot up again massively.
Hi Geoffrey, you're most welcome - thanks for the great feedback. I do worry sometimes that I get too deep on a topic and it will turn people off (particularly this video) but from the feedback I'm getting so far, it does seem that people welcome the extra detail - phew!
I agree with your points and, as always the case with technology, whenever and whatever you buy is soon outdated in terms of capability not long after you bought it. So the question is, to buy or not to buy? My view is that, technology never stops moving, so unless you're *never* going to buy, you might as well buy and enjoy the journey as much as the results :-)
I'm hoping that battery prices will continue dropping so that your 24 year ROI gets down to 6 at least...
@@GaryDoesSolarI’ve got two batteries, a 9.5 and a 5.2 on my two GivEnergy inverters, but I’ve also got an older FIT array with no battery so see most of the generated electricity going to the grid during the day. I don’t regret buying the batteries, they definitely improve the usability of the solar panel investment.
Trying to justify increasing the battery size with a 3rd battery though is very hard. Just not enough high/low rate price differential. Export rate helps but then insufficient charging throughput in the low rate window gets in the way. So I’m sticking to what I have
Agreed! 6 years or less would be a doable ROI for me!
Very helpful content about solar and battery
Many thanks for taking the time to give me this feedback. The video was particularly detailed and I worried it might bore people, but thankfully, people are finding it informative.
Another top notch video Gary. It isn't a simple calculation to make so I just answer this question with '"It'll be six and a half years until all my energy is free." Obviously this isn't the truth but it's so difficult to calculate.
When asked about 'break even' time I ask the questioner how much they pay per kWh. Nine times out of ten the response is a shrug of the shoulders but generally people, although not clued up, are realising that it would be wise to 'look into this solar thing'.
Keep up the good work! Tony
Thanks Tony! Yeah, I think the payback period for a solar-only installation is pretty much as you say. There's an initial capital outlay (vertical line up at the start) but then a massive saving on your energy bills (near horizontal line going up ever so slowly from that point) over the next few years. There's another line which has a steeper upward angle from the origin and where this second line hits the first, that's your payback period. See my video here for an example of that graph: th-cam.com/video/FvjuJQZRrvA/w-d-xo.html
Now, add in a battery and working out the payback gets a little more complicated, not least depending on how you *use* the battery. That's the conundrum I'm hoping to address over the nest few weeks :-)
@@GaryDoesSolar As with everything being active has more benefits than being passive so USE of battery is key. Also the tariff you choose sends the calculation off at a tangent as well. I'm still on Agile and getting a little bit of solar to keep the import level down. Hoping for a windy winter because recent plunge pricings have been a great help in keeping down costs.
It’s an excellent video. The point about ROI calculation is spot on, there are just too many variables. I always like to suggest to my viewers that it’s best to view solar and batteries as insurance and security products, rather than something more akin to savings and investments.
We all spend money on home and car insurance, but none of us ever hope to get a return on that money spent. But when we do get a return, we’re glad we spent the money on the insurance.
Same goes for electricity: long term it’ll probably get cheaper, but if it doesn’t, you’ll be glad you’ve got the investment to weather the price storm.
I’m making active enquiries into heat pumps at the moment, and one consideration with heat pumps is how the cost of heating improves dramatically when you combine the heat pump with Octopus Intelligent + a battery. I’ve seen one architect TH-camr ask which is the better return: heat pump or battery. My response is “why not add both together and then you can amplify the returns of both investments”
@anthonydyer3939 On heat pumps and batteries, agree they make a great combination as the battery can smooth out what would be peak rate usage with the heating on in the evening. BUT do consider (1) the battery inverter charge/discharge rate and (2) the amount of electricity required per day in the winter.
My heat pump can pull more than a single inverter can deliver (fortunately I have two inverters) but I could never afford nor be able to charge sufficient batteries to meet the daily demand which can be up to 50kW in winter. I’m anticipating the batteries will take the edge off the peak demand but I can never run the heating entirely on overnight electric
@@geoffreycoanI hope you mean 50KWh, 50 KW is a LOT of power
@@geoffreycoan At the moment I couldn’t run the heat pump off my existing battery. But the preliminary quote I have is for an 8kw system. That means that so long as the backup heater isn’t required, the max input will be closer to 2.5kW once CoP is factored. So therefore a 40kWh daily output would require an electrical input of 12-15kWh. Outside of the off peak period, that’s a 12kWh batteries worth of support.
But 50kWH of electrical input in your instance sounds either like a huge house, or sub optimal insulation / radiator coupling.
@@anthonydyer3939 Agree with your logic of working the home demand backwards to the electric required. My point was that even with 12kW battery storage required a day (just for the heat pump + home demand), that could be a challenge to fill overnight depending on inverter throughput and duration of the cheap period.
Yes I do have a big heat pump, 18kW (2x 9kW) because at the time there wasn’t an MCS approved 15kW that the heat loss calc determined I needed.
Typical winter daily heat pump usage for me is 20-30kW, so about £10 a day. Unfortunately on extended bitterly cold periods the consumption can double and I have seen 50kW consumed. Most of the radiators were changed in the install and it was designed properly. I’ve since switched on the outside temperature compensation and am now settled on running the pump 24x7 as they recommend so I’m hoping that the consumption this winter will be lower.
Overall my annual electric usage for the heat pump in the first year was comparable to the previous oil heater running costs so I’m OK with that.
Hi Anthony, I always love hearing your comments as you have a very good handle on everything! I hadn't thought of it as an insurance product (insurance against high prices as well as power cuts, I guess). And given the price hikes in insurance policies over the last couple of years, the differential between those and a solar and battery installation is getting a lot smaller!!
It remains a large investment though - and so I see ROI as a practical way for someone who does not large that level of capital lying around (and so has to make an opportunity cost decision) to make that investment, knowing that they'll recoup some or all of it over time. To me, saving the planet and saving money don't have to be mutually exclusive. And of course, with equipment prices coming down all the time now (thankfully) it's going to get easier to make an ROI case. What do you think?
Regarding your heat pump plans, I'm in the same situation as you. I know it's the right way forward, but I'm still a little worried about installing a system that doesn't give me what I have today with my gas boiler... I'll certainly be following your journey on this on TH-cam! :-)
Hi Gary, don't forget your battery round turn cost is £0.12 as per your example + Loss of SEG payment during the day or cost of overnight cheap rate charge x efficiency, which could be a 10% loss as you say. Great video by the way , first time anyone has included the battery usage costs.
Thanks and good point, Howard - I'm hoping that this video will show people that they need to be very careful when working out their payback... there are more 'costs' than meets the eye...
Also, you mentioned that solar is 'free' once the array is paid for but actually in ROI terms you need to consider it in the cost of what you are doing in the same way you're calculating ROI on the battery. So say your battery costs 12p/kWh, your solar may cost you an avg of say 5p/wWh, and actually energy from solar is then 17p/kWh. This makes a difference when you consider overnight you can get energy from Octopus at 7.5p, so its beneficial to import and use direct overnight, and export solar during the day, but remembering that the 15p/kWh export rate is actually getting you 10p/kWh, not 15p/kWh. The numbers are somewhat skewed with Octopus Intelligent giving such a cheap overnight rate, and I can't imagine that will last forever, certainly not once mass adoption of EVs happens. So its worth considering the ROI on the kit based on tariffs such as ECO7 as an easy to calculate option, and more realistically, the way Octopus will want to move it is into demand side management, where you take energy when its cheap and then use it when its expensive. I can see it being a bit like IO on steroids. Just look at the current incentive in the East of England where users are getting free electric whenever RE is being curtailed. That's when batteries will come in big time, if you can get free energy fairly frequently and charge normally when its cheap, and stay away from any peak usage, you will be doing a lot better than someone on a fixed tariff which has an averaged price across the day. We kind of see it with Agile, but not quite as I would expect it going forward.
The other thing to remember, is although a solar/battery combined cost of 17p may not seem great right now, in 10yrs with inflation, it will be a much better proposition. You're buying your energy now effectively at todays prices and locking it in. Same if you get onto Ripple, you buy your 'energy' now but the price they and you will get paid for it in future is likely to only rise (ignoring the fact that a glut of RE may come online and erode prices!)
@cingramuk correct, predicted inflation has not been factored-in with these calculations, tariffs can change at the drop of a hat, so these theoretical calculations are pretty much not relevant in the long term.
Too many variables to consider now, and in the future.
Just use it as you see fit for your own needs and enjoy the ride!
Unfortunately the more you delve into it, the more complex it becomes. I have a data cabinet that houses all my broadband, Wi-Fi, security camera's and NAS drives. Also because I have gone fibre and still retain a land line house telephone if there is a power failure I would loose it all. At my last house I had monthly power interruptions of up to 2mins and summer power disconnections of six hours for tree cutting along the power lines.
So I decided to use a 3,000kA UPS to supply the data cabinet which draws 120Wh all day and 139Wh at night when the camera IR lights are on, total 3kWh daily. Then I thought as I have a UPS why not power the house lights, Gas boiler and fridge just in case we get longer power cuts in the winter.
However, you loose all the roof 3.6kWh AC coupled PV power during a power cut, so I added an extra 1.6kW of solar PV that directly charges the battery, this is also more efficient 98% as it's DC straight into the battery via the MPPT charge controller and works during a power cut. I also charge the battery using surplus AC but efficiency is less around 90% and you loose any export SEG payment.
Hi Gary,
Great video and informative.
The question no one seems to ask is:
What's to stop manufactures/sellers changing the T&C's on battery warranties!
There's already unsettling talk in the car industry regarding car batteries as more and more issues come to light.
What I'm hearing from the EV industry is that batteries are fairing better than expected. For example, 8-year old Teslas still with 90%+ efficiency...
Loving these videos.
I would like to add a couple of terms to your calculations - cost of money (i.e. interest rates for borrowing / saving) and inflation.
I was fortunate enough to get a grant for a good chunk of the cost of my Tesla battery and pay 0% interest for 60 months (!) on the money outstanding. (The rest came from savings which at the time were attracting a miserable return of around 3%.)
As time goes by and inflation does its thing the value of the money I pay back decreases compared to day 0. I don't have the time to calculate how that goes but it must make a significant difference.
Thanks, and I like your suggestions, which I've made a note of, and might include into the utility at some point.
Thanks Gary. Another great video. I was very encouraged by the export tariff increase from Octopus. I’ve chosen to fill my battery every night to 100% meaning I export more solar during the day than before. I think this is a good balance. Thanks to your video I didn’t have to go away and work out whether I should be force discharging. There may be a benefit to forced discharging on an agile tariff which may be interesting to work out against eg the last year’s historic data.
Hi James, thanks for the great feedback. Now, it's funny you mention about completely filling your battery then exporting after that, because this is the same conclusion that I came to myself when making my next video (which will be on smart tariff strategies). I was surprised myself at the conclusions I came to!! Video should be out soon... :-)
James, I’ve also started charging to 100% at night then exporting any day generated power. I figure I’m helping grid smoothing which is important to me while also keeping control on our electricity prices due to the offset of price paid / export rate earned. ROI doesn’t mean a lot to me as you wouldn’t look at this for say a boiler. 08:30
@@glenpearson2287 exactly... knowing I'm putting clean electricity on the grid at peak times, that either came from the sun or overnight low carbon sources, is definitely part of the appeal.
I do the same. It seems like the safest option because it minimises the probability of running out of battery because it wasnt a sunny day and having to import at peak rate.
@@james123j1Exactly this.
Hi Gary. You have used a figure of £4000 for a 10KWH battery. I’ve had at least 12 quotes for batteries for my solar system and the cost for c10kwh is much more than £4k including inverter and installation. In fact the cheapest quote is £6650 with the highest being in excess of £8k. Over a 10 year period I’m struggling to see a decent ROI. I’m sure that the price of batteries will continue to drop which is why I have not taken the plunge yet.
I'm with you waiting
Wow. I got 6k PV, 5k inverter and 8.2kwh battery. 10k installed.
Just over a year of ownership and very happy.
£1100 direct electric saving.
£600 export payments.
Direct debit reduced from £140pm to £40 (5 months of that)
Over 2k ROI and sat on a nice bit of built up credit as well.
4000 GBP? Pylontec want 1k375 GBP for 5Kwh battery incl tax +ship.
An installer quoted me 4k8 GBP for 5.5Kw/10Kwh battery+inverter+extras all included, install + taxes, top-quality components. I figure 7 year ROI. Curiously, I cannot make solar PV pay off ever, but I haven't factored in this return -to -grid payment.
2x 15kwh packs here - £6k total for both.
Since April they have handled over 1,400kwh. The thing with Lithium Cells, same factories making the same technology but branded is just an expensive name badge!!
Hi Denis, for example battery prices, I went onto this site: www.itstechnologies.shop/pages/understanding-economy-7-and-maximising-octopus-go
Check out the "Typical Battery/Kit cost/kWh" columns...
I'll need to do a proper analysis but I am seeing battery prices fall - not least through companies like GivEnergy who are shaking up the market - so much so, that Tesla is dropping their prices too... You might not have to wait too long :-)
Thanks Gary this is great info as I'm just a couple of weeks away from have my solar and battery instiall so this is good food for thought. Also as of 25/9/23 Octoplus is lowering its prices from the 1/10/23 so for me going to Intelligent Octopus the rate is 7.5p from 23.30-5.30 and then 30.52p there after, so I be looking at that and the evening export tariff as well
Thanks for the great feedback! And I bet you can't wait for installation day! My own installation went in earlier this year, and I was essentially waiting a whole year for it! Hope all goes well with it all, and I think you'll really like the savings you'll get from IO. I need to get myself an EV so I can benefit from that too over the winter!!
Geat informative video as usual. Can you suggest your preferred system based on current products available at the current time. I recall you saying if you were starting again you would go ac coupled battery route. It would be great to see the system you have installed in your own home.
Hi Paul, thanks for the kind words. For those interested in my own solar and battery installation, I made a video for my Patreon members. If I were starting now, I'd absolutely go for an AC Coupled battery, and for the following reasons:
- they tend to have higher output (discharge rate)
- easier integration with EV chargers
- not much difference in conversion losses in actual practice
- would achieve higher export level with DNO
- potentially better EPS options
- not restricted to DC Coupled battery options allowed by inverter
Fitted and connected my own solar PV units with 2.4kWh pylontech.. have seen a drop in mains power useage by 2/3.. i will see this decrease in the winter as temp drops.. Fitted with help from a good friend... no electricution, no burning house and electric bill cut by 2/3... just need to get a DNO cert to go with octopus... :)
Brilliant - and I hope you get your DNO certification soon! Thanks for sharing.
There is also the security of not being dependent on the grid to factor in, especially in areas of the UK where the mains supply has become very unreliable.
Agreed!
I took the approach that I just put up enough solar and batteries to cover my critical loads, no need for a petrol backup to keep my gas furnace going in a Grid down. The actual return on investment is semi mute, but reality is on average people would be better off investing in the markets. If you will be getting a backup generator though....by far go with the solar option....it powers my gas furnace and some critical loads pretty much year round no matter if the grid goes down or not. By the time that money that was invested in the solar "Pays" off most of the components will need replacing....but I had it as a backup the whole time and never lost my heat/fridge/pc's and internet connection.
Fair analysis - thanks for sharing.
Your videos are insta watch 👍
Thanks :-)
A bit too optimistic of a view Gary - as an installer I can anonymously share that inexpensive Chinese battery brands rarely honour warranty claims past the first year, often inventing new reasons to blame the end user for the premature cell failure we're seeing increasingly.
Hey, I'm an optimistic guy :-) I agree though, that when buying any complex product or service, heavy research is your friend - for example, I chose GivEnergy, not only because of their highly competitive prices, but also their support. Many people choose Tesla - higher prices - but it... just... works.
@@GaryDoesSolar Both excellent choices - we sell 3 All in Ones for every Powerwall purchased but I suspect that will change when the PW3 arrives next year.
GivEnergy, Tesla, SolarEdge, Alpha and MyEnergi (few of which are available for £4K) are among the few who actually honour warranty claims with any degree of integrity. Once you go cheaper, your battery experience comes down to the luck of the draw!
As the adage goes...you buy cheap, you buy twice!
Well unless the warranty is insurance backed then at this point you have no idea about the longterm battery warranty. For example GivEnergy seems to be the most popular one pushed by installers but they have only been a business (in it's current form) for the last 5 years. Apart from Tesla none of the other companies are big enough to not fail if there was a major business changing issue. Even if it does end up being backed by insurance then nothing is a given as we all know insurance companies like to play by their own rules. I'm sure some insurance company has left you short changed at some point in your life!
@@gavjlewis As an installer, we see first hand how these companies treat their customers. GivEnergy are quite good and send their own engineers to customer sites when we cannot resolve the issue. Tesla and MyEnergi also very good.
Best of luck getting anything out of the unpronounceable Chinese brands on the market.
Nice video - as you say Gary there is no easy way to calculate this but just taking your approximate cost per kWh over lifetime and comparing that to peak rate is a good indication. I paid around 3k for a 6.5kWh battery which is warrantied for 10 years. Assuming 5kWh available average this means average cost per kWh is around 16p. Comparing that to today's peak rate gives some comparison to the value of battery in today's money.
Agreed and if you can fill that for free from solar and use it later on in the day then you’ve made a saving
@@geoffreycoan You may have made a loss! As on Flux you could sell for 18p (reduced to 15p today)
Thanks. Yeah, I was surprised that the ROI of batteries today is lower than expected. But it’s good that battery prices are coming down all the time 👍🏻
That's a really good talk, but I have just declined a battery quote because my consumption as a heat pump user invalidates most of the assumptions that the salesman made about payback time. Since I got the heat pump and abandoned gas entirely, I have halved my annual energy consumption in kwh, but on a cold day I might easily still use 60kwh in 24 hours.
Thanks for your kind words. Yeah, a heat pump can certainly use up a lot of electrical power over the day, meaning little excess to store in a battery. Where it might count though is those times of bright sunshine during the spring, summer and autumn months where you're not able to make use of all that solar, and are perhaps on a tariff that doesn't pay much for export.
@@GaryDoesSolar Good point, but there are three of us here all day, all computer users, and we only export in the summer. Still, that means that I am getting full standard rate for most of what we generate. I have just ordered an Emporia Vue 2, to try to find out where it all goes. Strange hobby, but keeps me out of trouble!
Good vid, always something else to consider. Do you think solar panel degradation play a part in costs like battery degradation does?
Thanks - solar panel degradation certainly has an effect, but to as much lesser degree - typically 15% over 25 years as opposed to 30% over 10 years with a battery.
It's actually even more complex, if you want it to be 😅
1. There's the opportunity cost for the battery funds, which could in theory have been invested elsewhere. E.g 5% per annum
2. There's inflation, which has 2 effects:
A - makes the absolute cost of the battery grow over time (assuming consumer battery prices themselves stay level - BIG assumption!)
B - energy prices tend to rise over time, probably increasing the import/export margin available (again assuming no other factors, like wars/speculation/politics etc)
... But overall having a ballpark cost of the battery per kWh at least makes it easier to spot the best way to use it... in my case, Octopus Flux just about has enough margin to cover battery costs when running a partial "import low, export high" strategy.
I’m on Flux as well and I don’t think an import low, export high strategy works by the time conversion losses are included.
If I import overnight at 18.4p then all it does is bring forward the point that my solar starts exporting during the day at 19.7p and the conversion losses will swallow this tiny ‘on paper’ profit.
Agree that there’s more profit potential between the overnight import rate and peak export, assuming your solar panels can’t fill the batteries (e.g. small solar array or cloudy day or large battery array)
@@geoffreycoan yes absolutely, that tiny difference between import window and daytime Flux rates will not work, it has to be the 4-7 peak with it's 13.2p nice margin - that works (even after including all costs).
This is why I only import overnight to avoid having to buy expensive electricity later. Any spare is calculated by my code based on today and tomorrow's solar forecast, and what we will likely use ourselves. Sunny days get lots of export naturally, but gloomy days mean none.
I aim to export ~2.5 kWh in the peak but if the weather or our loads mean there's no spare, we send much less or even none back to the grid. This keeps me under 0.75 battery cycles a day and maximises returns whilst minimising import.
@@geoffreycoan Ok... just got the price reduction notification from Octopus and the best margin is now down to 11p. So including losses and battery wear there's even less in it now.
So I think I'll turn my target export down to 0 and look at different tariffs, Flux is not worth it in the winter at these rates.
Yeah, I'm of the mind that the Cost per kWh for the battery should only be used for day to day battery management and not for the ROI. Instead, the ROI should be calculated along the lines of the chart at the end of my latest video here: th-cam.com/video/eFWYFip6qYM/w-d-xo.html
One of the only good things about inflation is that your battery cost is up-front, so the money you spent on it, diminishes in real terms over time, whereas everything else, including energy (as you point out) goes up.
@@GaryDoesSolar agreed.. as said in another comment, the battery only really makes sense as an pure investment as part of a wider strategy to electrify and use cheap grid or free solar energy. My point above was that there are so many real world variables that it really depends on the individual house and setup (plus inflation, regulation, geopolitics, luck and so much more 😅)
But! There are people that assume the arbitrage of grid electricity is worth it with a good tariff and just a battery. Your video shows that they need to be careful, because without solar the real world (after costs) margin is probably quite low.
For the ROI one might need to do an NPV calculation, where one assumes the capital outlay has to be borrowed (or at least is no longer garnering interest as investment)
That's a fair comment, Andrew - thanks for raising!
Thank You Gary for such an informative video. But isn't it true that extreme heat and extreme cold affect the life of a battery, too?
My pleasure :-) Glad you enjoyed!
Re. battery temperature, yes, it's true - although many manufacturers (such as Tesla) include heating capability inside the battery to counteract.
# Gary Waite The way I try to work out is document how many kWh the battery charges and discharge and simply multiply with the prices of electricity.
That will take time of course but it will tell me is it worth investing into a new battery.
It looks a simple but effective method to get a feel for battery ROI - I like it :-)
A lithium battery pack (specifically LiFePO4) is run into the ground once it goes much below 70% of it's original capacity due to the chances of having an increased rate of cell failures. Failure rates in all lithium batteries increase once they drop below 80-85% original capacity. Most litium batteries used in home solar are going to see far less than a full cycle in a day. My home battery bank only sees about 25-30 full cycles every 3 months because it never goes much below 30% and stops charging at 100% full. Most days it has more than 50% left by the time the panels are producing the next day. Nearly all home solar battery banks are going to suffer from calendar aging failures long before they reach the point of charge cycle failures. Calendar aging for most LiFePO4 cells is around 1-1.5% per year with an expected calendar life of around 15-20 years in mostly ideal conditions.
Thanks for this great insight. If you don't mind, I'll add it to a pinned comment I'm making in the next day or two, to benefit others. I'll of course credit you. Cheers!
If your % utilisation is so low is a battery still a good investment I wonder. The £/kWh only increases.
@@wemorgan he might want backup power. They drop with a few days horrid weather. 30kwh here and been over 70% most of Summer. They are dropping further over 3 cloudy days now to effectively make one pack a 15kwh UPS by limiting discharge to 40%.
We'll be hearing about Blackouts again soon, your government just kicked the can down the road and wind investment bidding didn't attract a single player.
We're down to one Coal station out of the 3 last year and about to loose a Nuclear reactor with no replacement.
Yet government believes that the rest of the world needs to catch up?
Erm, we're a little stuck for alternatives when the Wind doesn't blow as Gas was regularly at max last Winter and very expensive.
Demand Response Days ring any bells?
Oh Rishi - what have you done?
I'm expecting there will be a strong battery repair market in 5+ years. Taking Pylontech as an example, the chassis, connectors, BMS and shipping (because they're very heavy) must represent a good portion of the cost of the unit. I can't see why it's not possible to get new cells to put into it, then send them old ones to be recycled 🤔
@@TheBadoctopus although 3rd party Cells would be the cheapest option. Prismatic Cells are the best as easy to swap out singles to a pile of flat packs.
Solar and Batteries connected are not working very hard even at full rate when multiple or larger packs are in involved.
Our packs combined have max 1C charge rate of 400amps, the Inverter can not exceed 100amps 0.25C, which is split over 2 units giving 1.3C max per pack and rarely do I see the full power as usually its a variation depending on clouds.
Even full load, they are nowhere near anything stressful. Prices of Cells are consistently getting cheaper, especially the 280Ah which are becoming popular elsewhere so driving down costs.
The packs I have are cheaper because for 15kw, there is 1x BMS, 1x case and 16 Cells. Taking a 4kwh or 5kwh equivalent would need 3x BMS, 3x cases and 48 Cells which is where the money is. In a few years time, I plan to change the Cells to sell on to Campervan owners and put a fresh set in.
I have just pulled the trigger on a 19 panel with 10KW battery with EON. The overnight cheap rate is 6.9p and the export rate is 40p. A no brainer funding the battery and even considering adding another 10kw.
Hi Nathan, sounds great! I'd love to hear how you get on once it's all installed if you don't mind! My email is me@garydoessolar.com :-)
Can you make a video about the best set up for a system totaly off grid for an everage home
I’m not an expert in off grid installations but you should be able to search for suitable videos on TH-cam - good luck 😀
Given a battery (which I think does have a strong ROI, both shifting home consumption to off peak and maximising self consumption of solar.
With the current OI rates I’m charging overnight, and allowing excess solar to be exported. I’ve also automated a force discharge at the end of the day - so in summer I’ll export a good deal of my generation… which pays for the standing charge nicely.
Sounds great 😀
@@GaryDoesSolar the export rate does change the way I use the battery - with a charge cycle being “full in the morning” now the norm, whereas it used to be “guess how much I’ll generate and use” generally getting full at some point in the day and emptying significantly overnight.
Hello again Gary, how does receiving feed in tariff affect all these time of use/octopus tariffs. I haven't seen them mentioned at all. Brian
Hi Brian, I don’t cover feed-in-tariffs in my videos as these schemes (at least in the UK) are no longer open for new applicants. It should be fairly easy to account for them though in the solar ROI calculation (not the battery ROI though).
@@GaryDoesSolar ok thanks again
I am installing 12KW of panels and 40KWH of battery. I am designing and installing everything myself. The solar panels are new surplus and still eligible for tax credit and only $4,500 after credit.I am buying a salvage Chevy Bolt and parting out the battery for the house, RV, and boats. In total I will have $18K in it and I expect < 8 years payback with no selling electricity to the grid.
That’s great to hear, and will be helpful to others thinking about making the jump- thanks for sharing 👍🏻
The best battery for home use and grid storage is (or soon will be) a battery that doesn't use Li. And all they need is market share to be less expensive than Li batteries. They are made from cheap elements that are readily available from multiple sources. They can be cycled between 0 and 100% charge with no damage, last far longer than Li batteries, are safer from a fire point of view and would be far easier to recycle if you ever needed to recycle them. There are two types of ZnBr batteries (Flow/plating and gel), a molten metal battery based, so far on Sb and Ca, a range of redox batteries using V and Fe and the up and coming Na battery. Note that each cubic meter of sea water contains about 15km of Na. Na batteries, unlike Li batteries, can be fully discharged before shipping, reducing their fire risk to zero.
Na is by far the most optimistic. Fingers crossed it will be big here soon. ZnBr economics are funny: so far same as Vanadium. Why? Dunno.
Ok, you've got me interested in researching these new battery technologies! In general, I love human ingenuity in how we are able to use the minerals around us in innovate ways and processes, to continually come up with better and better technologies. I remember when my friend studied batteries as part of secondary school project (40 years ago) that then, battery technology progression was slow against other technologies. We look to be making up for that now though - I feel we're on the cusp of one or two major breakthroughs that will mean far cheaper and higher capacity battery solutions for all manner of applications (home, car etc.) And maybe that starts with the technologies you outlined... :-)
Hello Gary…..a question if I may please. With less Solar gain as winter gets closer, is it possible to charge the batteries from the mains using low cost electricity in the off peak periods? If so how…..I have a standard PodPoint chrsger with GivEnergy batteries and inverter. Much appreciate your thoughts! Thanks Chris
Hi Chris, yes you should be able to charge your home battery via the grid - this is called “force charging” - just check the data sheet or contact the manufacturer for details 👍🏻
@@GaryDoesSolar t(bass Gary when you say manufacturer do you mean PodPoint or GivEnergy?
@@chris58smith Ah, apologies - I mean the battery manufacturer. - in this case, GivEnergy. You can control the battery management via the GivEnergy app on your mobile phone, or via their givenergy.cloud website.
@@GaryDoesSolar many thanks Gary. I’ll give them a shout.
Wonder if this is worth a video….a lot of users might see the benefit.
Video as usual. However, not all of those actions are possible with every system so probably worth adding the System capability as a factor to whether you can do all those actions..
Yeah, with some batteries, it's not possible to program them to force charge and discharge. Definitely something to check for when choosing a battery.
Even with $ 0,65/kwh for electricity now in Germany (MSM only announce the prices w/o basic costs!), the ROI of my 2018 installed 13 kWh BYD LiFePo battery is not paying itself, BUT having had brownouts in the last years and the idiotic electrify policy of the German government (they closed all nuclear power stations, and already started closing coal power stations on April 1st!) which has made Germany energy import dependent with up to 50% each day as wind and solar doesn’t work year round as a NPS or CPS, im happy to have the battery backup system.
Average runtime of wind power stations in Germany is roughly maxing out at 2.000 h of the available 8.800h of a year…
Solar power is down 30% of the possible power due to chemtrail clouding the sky.
With battery prices coming down all the time, the financial ROI will soon become possible...
Going with Octopus is good advice. It is probably best to get their advice on what systems to install at an early stage in your project(s). This will avoid the situation of not being able to exercise the full range of options because the controls in your system lack compatibility
I totally agree!
Thanks for this - useful things to remember.
My question about your calculation was the bit where you said that it loses money to do the 'overnight shuffle' arbitrage trick. You said that the true cost per cycle is 12p but I thought you said earlier that if you do 2 cycles per day it is only 6p. If it is part of a two-per-day cycle then wouldn't this still be profitable? Or does that ignore something, like battery degradation cost or something like that?
Hi Doug, do you know what? I think I made a mistake in the video I posted yesterday! If the cycles are less than 1 a day, and we're using the "Under Warranty" formula (from the video you just watched) you're right - the Cost per kWh will go up, not down!
And this makes sense, because you're essentially only planning to use the battery during the warranty period, and so using less kWh means most "Cost per kWh" has to be applied to meet the amortisation requirement.
I'll make a correction to the latest video - thanks for spotting!
For the "Run It Into The Ground" formula, things are different, but I'll need to think this through before commenting!
@@GaryDoesSolar Yes, the 'run it to the ground' formula is going to have to involve an assumption because you don't know how long the inverter will last. I suppose you could take an average of warranty + 25% or something like that, and then the person might get lucky and get 50% extra or be unlucky and only get 5%. You've probably already thought of that but I'm trying to get my head around it all!
@@dougbamford Actually, I'm still working on the 'run it to the ground' and it's doing my head in! Lol
12p per kwh cycle I think is quite optimistic. The bottom line is that unless battery prices drop significantly, they aren't a good investment, really.
Hi Michael, I agree - current battery prices make the ROI potentially marginal, but thankfully, battery prices are dropping all the time (price per kWh)... be careful what you wish for! :-)
@GaryDoesSolar our system is battery ready, but having Fronius inverters, we are limited to BYD or LG battery systems, i.e., premium. The equivalent cost for a 10kwh battery works out at 20p per kwh cycle! Sometimes, though, we don't make decisions on ROI.
@@michaelheathcote9488 What's interesting is that when I look at the actual number of cycles per day since my installation went in earlier this year - what I thought was 1 cycle per day turned out to be about 0.5. Maybe the same for you then, meaning your cost per kWh will be lower?
It totally depends on what u get for exporting and how much it costs to draw from the grid - there just is no general recommendation considering the vastly different contract options around the 🌎
Agreed - and I hope I got this point across in the video. The reason why I'm going to add an ROI calculator to my Solarazma utility is because that utility, if configured correctly, has a very detailed picture of your setup, tariff and usage.
But the 12p Kwh battery use is applicable to self use too ??? Add to that Flux PER on IOF tariff
Absolutely, which means the difference in what you paid to generate the energy in question against what you would have paid to import instead would need to be greater than the 12p… For example, buying at 7.5p to avoid buying at 30p.
Just to be clear Gary the 4.5 p loss you mention is the conversion losses associated with converting the AC to DC then back again ?
Hiya. No, basically the calculation is as follows:
Price paid per kWh = 7.5p (cheap import rate)
Price sold per kWh = 15p (export rate)
Cost per kWh to use battery = 12p
Profit per kWh = Price sold per kWh - Price paid per kWh - Cost per kWh to use battery
= 15p - 7.5p - 12p
= -4.5p (loss)
Conversion losses are actually in addition to this, because to export say 10kWh from your battery, you needed 11kWh to fill it (10% or 1kWh lost in AC/DC conversions)
OK Gary so its all about getting your battery to last as long as possible and only export when taking in to account the import/export differential .
So overnight last night my Agile tariff went negative at an average of about -2p per unit and taking your calculations my profit would have been about 4.5 p a unit .@@GaryDoesSolar
@@radiotowers1159 Yeah, with those Agile rates, you can make a good profit with a battery :-) Long may that continue!
I'm came to the same conclusion as you its very dificult to work out ROI on battery only as you have to consider the usage pattern and the tarffs avaliable and how you work with them going forward
Yeah, it’s a shame it’s more complicated but with battery prices coming down all the time, the ROI becomes easier 👍🏻
Don’t forget, the loss of energy between loading the battery and emptying the battery. As with any EV, loading loss is roughly 19%!
So, if you load the battery with 100kWh, the battery itself will be only loaded 81 kWh in the end!
The hard/software of my system backup uses 60W/h means a whopping 1.2 kWh/day, too.
The battery system is set for 30% brownout power reserve to keep the fridges and basic system as heating running.
So, Tesla quotes 90% round trip and recently, on a GivEnergy stand, they were quoting 93% round trip...
@@GaryDoesSolarwhat do you mean with „round trip“?
Charging loss is real. And quite a lot.
@akkseljohansson3601 Round trip losses are the total losses from storing energy in a battery to getting energy back out again. So if a battery is charged with 10kWh, but only discharges say 9kWh then the round trip energy conserved is 90%.
@@GaryDoesSolar we only state the loss in Germany. In your example that would be 10%. My BYD LFP system has a 19% loss or 81% round trip as you call it.
German automobile road assistance ADAC also checks annually the EV losses. They now started the measure of the losses of EV charging stations.these are ridiculous high, too.
Gary, living in the UK isn't correct for Octopus, it's GB only. N.Ireland is part of a different energy market, with antiquated tarriffs and no flexibility whatsoever.
Fair comment, and such a shame that NI is not embracing what is inevitable.
Thanks - another great video. I'm looking at getting a zero interest loan from our mortgage provider over 5 years for a solar system - up to £15k, but need to make it work to sell it to my wife. Are you going to do a video on n type vs p type? I'm trying to work out if its worth the extra..
Energy savings trust is your best friend on that one.
@@BlackBuck777 Cheers..
Yes, energy trust will help - good luck!
I'm in Scotland, and I think they do different things. They definitely don't do an interest free loan any more, unfortunately, which is why I'm looking at the mortgage provider, who are apparently doing a limited amount. As regards n-type Vs p-type solar panels - it looks clear to me that given the £15 or so per panel extras that an n-type panel costs, it's going to be more cost effective to buy n-type, but I'm wondering if I'm missing something obvious, as it's barely mentioned anywhere?
@@Danothebaldyheid When I looked at panels for my won installation, I wasn't concerned about the technology used (P-type or otherwise). What was more important was the percentage efficiency of the panel - in other words the highest amount of generation for a given area size. Hope this helps...
You don't mention the warrantee of the inverter which is usually 5 years. The inverter is unlikely to last 10 years and the replacement may be expensive because of installation charges and matching the original specification.
I worked on the basis that inverters would last 10 years (about the same as the battery)
I'm thinking of going Solar soon, as someone who is on the fence. Is it worth waiting another year, or two, to see how the tech evolves?
Solar panels are very mature today. I would not wait. But only add a battery if your energy use is high enough to warrant the investment
Solar is an absolute no brainer if you have the ability to put a minimum no of panels on your house or property. You can plug a battery in later to your existing inverter.
I got 6k PV, a 5k inverter and an 8.2 givenergy battery for a touch over 10k.
Had it just over a year. Granted at the height of the energy chaos.
£1,100 direct electric savings (via PV and battery + time of day tariff like Octopus Go / Flux - I change as the seasons warrant it)
£600 and counting export payments.
And for 5 months since April, I lowered by direct debit down from £140 to £40pm
Basically from Sept '22 to Sept '22 over £2,100 in savings (or ROI)
With electricity coming down to more normally levels I expect to only recoup £1,500 this coming year.
Still, looking at 6.5 year break even.
You really need the smart tariffs however, and even then, during the winter our battery will run out on occasion.
Still, using common sense, and setting timers for washer, drier, dishwasher to also start during the 7.5kwh 4 hour window helps as well
If you're unsure - use the Grid as a battery. Stick in a straight Grid Tie and Export as much as you can to offset Winter and cloudy days Import costs.
You'll not loose with or without battery as long as you aim your heavy loads while the Sun is shining. We use 3kwh overnight- so around £360 per year night Import at 27p.
I first looked at 4kwh Lithium 7yrs ago- £22,000 so went down Lead Acid instead. In all, lost around £200 but good value for power failure peace of mind.
Some great replies to your comment already. Worth watching this video I made 8 months ago: th-cam.com/video/FvjuJQZRrvA/w-d-xo.html
Since then, prices have been falling faster than even I thought...
Where did you get the sudden cost of 12p per KWh
Did you watch the video? It’s not a fixed value - it depends on the cost of the battery, the capacity and how long you think it will last. There’s a formula in the video for it 👍🏻
You missed the option of charging the battery off peak to use during the day and sending solar back to the grid.......
No I didn’t - these are covered by these two actions in the video.
Grid > Battery > Home
Solar > Grid
You dont have an option for charging the battery off peak and using that in the day whilst sending as much solar back to the grid as possible.
OI has only just swapped to a reasonable 15p feed in, which I am at present swapping to. Even without that feed in my battery app is telling me I have saved £1750 in 6 months on top of the £750 I got from my 10 year old solar feed in.....@@GaryDoesSolar
This question is largely irrelevant, at least in the US. If you have a Grid Tie system and the grid goes out, so does your system (required by Code). It may be cheaper, but it's useless. If you are off Grid and don't have a battery, your system only works half the time. So the question ultimately is how much battery should you have?
Gary is UK based, where the grid is very stable for the vast majority of consumers, thankfully.
Agreed Patrick, in many parts of the world, having a battery to provide a stable electricity supply vastly outweighs other factors, like cost. Where I live in the UK (rural Oxfordshire) I might get maybe 2 or 3 outages a year, and even then for maybe 1-2 hours each time. But, we're living on a planet where local climates are becoming more extreme, and this together with an increased percentage of renewables use, unless we can get/keep in place precise grid management, I think we'll all have to put local backup facilities in place. Thankfully, the latest AC Coupled batteries have this capability (EPS) built in.
In terms of the best battery size, might be worth you watching this video I made on the topic: th-cam.com/video/3vwDrfuXyik/w-d-xo.html
Octopus has installed our h.p. but I'm afraid that aftercare service is so far almost non-existant. I believe that they are grossly understaffed and seem to have poor customer service structures. I'm on OG for our EV and home batteries but there is a complete failure to respond to significant enquiries.......
Really sorry to hear about this. Could you describe a little more about the issues, and how are you making contact with Octopus? I've heard that Twitter (because it's public) generally gets a quick response. I normally use email and get responses same or next day...
@@GaryDoesSolar I used to email because *they recommend it*. If I had £1 for every 30 mins that they leave me hanging on the phone..... I'm just getting really cheesed off with the lack of follow-up after everything that was promised. They have even made unauthorised deductions on the d.d.!
Gary. Can I contact you Need guidance?
Hi Marc, I’m not set up to provide individual guidance. However, on my Patreon, I do run a periodic Q&A where I try to answer as many questions as I can. Sign up here: www.patreon.com/GaryDoesSolar
Why do we always need ROI on an energy system but we do not need it for anything else we buy? We don't go what is the ROI on the car I will buy? better questions need to be asked to make the system work better for your home. I feel if you just work on ROI for the purchase you might end up getting something less effective and then regret. I regret not understanding how investing in other things in the home can affect usage and then planning what we need.
The need to calculate ROI is of course a personal choice for everyone. And for those who can afford the investment, the fact that they are able to do their bit for the environment might be sufficient reward. For many though, coming up with a £10K+ investment is not easy, and so by looking at ROI, a go/nogo decision is made easier. I'd argue that ROI is important to many people - including myself.
@@GaryDoesSolar I guess you could be right but you ignore the importance of ROI. You look at ROI as a financial gain. I think it should be deeper and more questions need to be reviewed. I’m happy you were able to purchase the system when most middle class at the moment consider themselves poor.
@@jasonrhl In the context of my video, the term "ROI" was specifically financial ROI, but you're right - ROI can also expressed in terms of energy security and doing your bit for the environment. For those that can afford a solar and battery setup, the latter two may be seen as more important aspects, but the for majority, as you say, it's a heavy financial burden and so looking at the numbers is just as, if not more important.
A LFP battery in a EV is drained much faster than a battery in a home. Our Tesla Model S batteries are now 10 years old and mainly fast charged and driven 350.000 km and have only lost on average 1% per year and those are not LFP chemistry. So a home battery should last 20 years in my opinion. Our brand new Model Y has a LFP battery and should last longer then our Model S batteries.
Thanks for sharing - the future is looking great for battery storage!
In The United States it's not cost effective to export solar energy to the grid. We get next to nothing for it. It's best to use a battery to store the extra and use it when you need it. Once it's gone, switch back to grid. If you even need to.
Expecting utility companies in America to pay you for anything is a joke. Utility companies here started finding new ways to charge you more if you do install solar. Regardless if you export or not.
Hi Kevin, thanks for sharing this information. It's such a shame that US utility companies are not embracing the many new business opportunities that come with a highly-renewable focussed grid system, but I think it will come. Here in the UK, the energy companies are starting to wake up and follow Octopus Energy's lead. More and more are increasing the payments per kWh they make for exported energy. Octopus is present in the US now as well, so hopefully, we'll see them shake up that market (slowly, but surely) :-)
The get rich quick scheme doesn't work if you are thinking about buying a battery and you want that price arbitrage to help pay back the capital cost. Just as you describe.
However, if you have already bought your battery then the capital cost is a sunk cost which should have no part in your subsequent strategic thinking. Therefore, it is still rational to charge with Intelligent Octopus Go at 7.5p/kWh and then discharge with Fixed Octopus Outgoing at 15p/kWh. The notional 12p/kWh cost of operating the battery is irrelevant because it has already been paid on day zero.
I would argue that even if you have bought the battery, many people will be looking for a return on that investment, and by working out a cost per kWh for using the battery, this helps with how you can use your battery in the best way. In the next video of my latest series, looking at strategies for smart tariffs, I'll be looking in more detail at various strategies. For example, it would be better to fill your battery will cheap energy, then NOT discharge it for export, but keep it full and simply export the solar generation instead. The charge in the battery can be used to power home appliances later in the day when there less/no solar generation. Both of these actions should generate a higher return than the 'get rich quick' scheme, in my view. I'll of course this using the Solarazma utility.
@@GaryDoesSolar yes, the capital cost (per kWh) has to be considered in the ROI calculation, but definitely not in the operational strategy after you have made the battery purchase. Operational strategy is always about comparing the cost of one action vs another
@@redshift3 Thanks for taking the time to debate this with me. I think we'll have to disagree on this point, but I'm always open to different opinions and I'll keep what you're saying in mind as I get deeper into the analysis 👍
@redshift3 So, I've been wrestling with this whole thing for the last couple of weeks, including thinking about your comments further... I wanted to follow up on this thread to tell you that I've come round to your way of thinking on this:
1. If you are looking to *buy* a battery for an existing system, then the cost of using the battery should be considered, to see if there is actually an ROI, excluding ROI from just the solar part.
2. If you already *have* a battery, then the cost of using the battery is less relevant. The deal is done, so it's now all about working that battery in the best way.
The ROI of the whole system canned should be calculated independently of the above.
Thanks for taking the time to persuade me.
isn't a EV car with vehicle to home charging make a home battery obsolete? they are much larger in capacity and sitting on your drive for free
It will be when both car tech and 2-way home EV chargers finally arrive to do this properly.... until then we wait for the industry to catch up.
So not many EVs have the V2G implemented/enabled at the moment, but when it becomes commonplace, I think that some people will choose not to have a home battery as well. But, I can imagine that most people will want to have both - remember that the car won't always be at the home...
@@GaryDoesSolarIndividual lifestyle will dictate the best solution. But when not at home many home's base load is low. So using the grid is ok.
Peak power is 30p / kWh vs 7p offpeak for charging, so depending on how often your car is away during the day it may still be worthwhile.
Not sure I'd describe a 25-45k EV sitting on your drive 'free' lol, but I see what you mean.
Batteries need to come down in price before they go mainstream. Buying Tesla Powerwall is like buying the first generation, 26 kWh Nissan Leaf, Pathetically weak Powerwalls are the poster children for the homeowner’s version of range anxiety! But Powerwalls are so expensive, they make zero financial sense. We need solar and home storage batteries; we need the robust, distributed power, the ability to charge our EVs at home, and the ability to break the stranglehold that price gouging, corrupt, and polluting, electric utility monopolies have over the electricity markets!
Having raged against expensive and weak Tesla batteries, now something positive. Very good and useful video! Thank you!
No problem - always good to vent once in a while. The good news is that Tesla is continually and progressively reducing their battery prices. It won't be long before battery technology will be a must for every property - even if solar is not an option... :-)
Interesting video. However ROI is used incorrectly. According to its definition ROI (return on investment) does not have an information about time and is not a chart, but a single number.
ROI=( Investment Cost / Net Profit )×100% If you don't believe me, google ROI.
Your calculation is certainly relevant. But please do not call it ROI. You cannot just use names that are already defined in financial terms and use them for something different, just because it sounds nice.
Including the time in financial calculations is important because it makes a difference if you 'earn' $1000 in one year or in 5 years.
There are better ways to describe financial outcome of an investment that consider time; for instance net present value (NPV) or internal rate of return (IRR).
IRR is especially interesting because it gives you a percentage value the you can directly compare to the return from a bank account.
Happy to be challenged.
ROI does indeed include a time element. From Wikipedia:
"Return on investment (ROI) or return on costs (ROC) is a ratio between net income (over a period) and investment (costs resulting from an investment of some resources at a point in time)."
The term "ROI" may have been born in the finance world, but that doesn't mean it has ownership. It's just three words meaning, quite literally, getting something back from an investment made into something. It doesn't have to be financial at all. A boy investing his time with a girl in order to successfully get a date is an ROI. So, I'm happy enough to use the term in the context of investments into solar and battery, as many other people do already. If that were not the case, nobody would ever watch my video because the title would be deemed meaningless.
I stand by the conclusion I reached in the video that a chart showing graphically how and when the ROI is achieved is the most effective way convey such information.
Make your own battery use used recovered cell's from a Tesla that crashed
Great idea (for those that know what they're doing) and good reuse of resources :-)
Stop quoting rate of return you don't have that mentality buying a new car .... battery £10k new ev £20k plus which depreciates as soon as you drive it off the forecourt
You don’t know the first thing about my mentality….