Connecting the Solar Array to a Hoffman PV Combiner Box, Off-Grid!
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- เผยแพร่เมื่อ 6 มิ.ย. 2024
- Today I finally got around t replacing the dangerous "temporary" wiring from my ground-mount solar array with a proper combiner box, conduit, fittings, etc.
WARNING: Lithium batteries are dangerous and can result in fire! This video is NOT intended to be instructional or a "how-to" lesson. I am not a professional. Do not attempt anything you see here without first contacting a certified and/or licensed professional.
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Hoffman boxes are top notch, used them exclusively in great quantity (Nema 4, 4X from 4x4 boxes to 6' DD cabinets) for a long time and their back panels are excellent. A Greenly knock out punch set would be a nice addition to your tool kit! Nice Score on the boxes! Really nice and proper job with proper feed thru's on the wiring and routing with good tips and tricks. Well done and thanks for sharing this with the community!
My over engineered self lusts for 4X and a much larger box for hand access!
ABB boxes are thicker but the ones we used had removable knockout plates with cork gaskets.
30 years in telecom - USA and Canada - We use Hoffman boxes almost exclusively. Now you know why.
steve myers apparently this box viewed was made in Mexico...part of the nafta trade agreement.
You have a talent to explain step by step well enough even a newbie would feel confident to do this.
Excellent "How to DIY" video! Very informative and descriptive narration!!!
Hey man, iv been out of the group since I built my pack before you started making videos, and just came across your videos...awesome to see you making them!
😍😍This video along with the rest on your channel are outstanding! You've obviously a very good teacher with camera and audio skills too. I'm a noob with more electrical experience than the common dodo....and will be trying this soon. Thanks for all your efforts and keep trucking!!👊👊
LithiumSolar, you said thanks for watching! Well all I can say is thank you very much for the making the video!! It is really going to help me so I can do my own now 😉👍
An interesting video. At last, I learnt what that blue tool should be used for. Thanks for posting.
I love your videos man, they're always filled to the brim with info and excellent tips and tricks to help even the most amateur of solar enthusiasts and make it not so daunting of a task..another great job @LithiumSolar 👍
You are so right!
This video was super helpful and exactly what I've been looking for.
Those are clearly clean,compact and tight boxes. Was afraid you had dropped the negative screw you removed down your conduit for a minute. It was close! Another good video and I enjoy learning more new things about solar systems every video.
It fell down into the right PV bushing and I had to dig it out. That would have sucked it it would have fallen down the conduit... LOL
Getting it done like a BOSS!
If I anticipate trouble getting wires into flex conduit, I'll pull the wires while it is lying straight on the ground, then install it.
They make lube 🤣
No really you can buy conduit lube for wire pulling, looks like a bucket of what you’d expect an elephant to produce. But try running Russian certified, GOST not UL, cables from a telephone booth sized motor starter 40ft down a skid without it. It was a vapor recovery skid for petrochemicals.
Exactly. I always run my wires through the conduit first. A hell of alit easier. Especially if your running more than 50 feet.
You always find the best deals on solar/batteries
The deals seem to find me these days...
I just scored some 245 watt panels for $50 each used. This video is a great heads up for the project ahead!
A very useful video brother and thanks for sharing.
Brilliant Tutorial ❤
A Great guide. Going to improve my set-up with your idea's
Good Quality Work
Thanks a lot. That was very illustrative.
There are many PV videos around.
What I like about yours especially is the safety factor.
I have always thought DC electricity to be safe and wouldn't take precautions like I do around AC. You point out why DC is dangerous and i need to heed your warnings.
Great video, very informative! Thanks very much!
Great video as always Mike
Excellent work.
There's no such thing as a water-tight seal. Drill holes on the low-points of your conduit for water to evacuate. This will help with regular weather changes like condensation and pressure changes. You're not waterproof if you don't evacuate water.
Brilliant video!
Better yet install a piece of rigid conduit with a T box and at least a filter drain to keep out the critters.
When I worked the petrochemical industry we couldn’t allow pooling, because it might be explosive so no flex except for the last 18” and a T and a drain on every low point. The box needs a drain too since condensation will fill to the level of your bushing.
Nice clean build. Only thing else I would suggest is a lightening surge suppressor.
not a suggestion, it a MUST!
Great video
I like that enclosure, 50 bucks is a good deal!
Yeah deal is gone unfortunately :(
Thank you for sharing I will be installing my own soon do you have a disconnect as well inside your home like how will you shut off your 600-volt charge controller
I have so many crimpers but I need those dies. I do mostly lmr400 cable with mine and other antenna cables. We dont use MC4 connectors at work but bought 10 pairs of them for my personal projects.
Another Great Video!
I wondered about those fuses instead of breakers but I got 4 years on mine and still same fuses so must be good.
AAAAMAZING EXPLANATION, THANNNNNNNNX
Awsesome video. Just a question, would it be possible to use dc circuit breakers instead of fuses?
I like the Hoffman boxes or at least the ones I used on my solar installations.
Hey Mike, well done - it’s clear you put a bunch of thought and work into this. The whole video I was worried you were going to leave the cover plastic on the box 😂 thanks for showing you removing it hahaha
Hi , good video,could you telme whwt is the technical name of the negatives conection block? Thank u..
Feels cool to work like that 🤪👍
Can you explain how you grounded your panels. I assume you bonded them together with a number #6 copper wire back to the grounding bus bar in the combiner box?
Thank you for the video I'm getting ready to set up a 4000 watt pv system did you install a master disconnect some were in the system I was told the system needs one I was looking at the eco worthy combiner box but after seeing this I see that this is the way to go
I do not have a master disconnect at the panels. I have a main disconnect (PV-rated circuit breaker) at the other end of the wire run.
@@LithiumSolar ok I'll look at that option also
Nice one
My solar array only has 70v max unloaded, so I don't need to worry about high voltages, but I still am careful with it because of arc flash, it's around 1/3 inches long so ya don't want that happening uncontrolled.
At some point when I have a more permanent array and a higher battery voltage I want to have the panels in a field with a higher voltage so there's less line loss.
8.30.20 Thanks for the video. For me a learning experience.
Definitely come back with the panel ground video.
Yes
When you put the fuse in are your fingers contacting the +VE ? This is a great video and i really appreciate the detail you put into it. You brought everyone along. Thank you
No, the fuse is not making contact on either end at the point of insertion. That would be extremely dangerous if it were.
what is the arrangement of the panels coming into this box? (series/parallels ect)
At 5:00 Stop. Do not try to assemble the flex while the connector is in the enclosure. Remove locknut. Build in your hands tighten after assembled in your hands, then mount assembled flex to enclosure with locknut. Support flex within one foot of box. Pull then land output wiring before panel array feeds go into box. You're a good hand, but you are new to electric work.
The Midnite Solar combiner boxes are insanely expensive - but I used them because they allow for an integrated quick disconnect. How do you feel about adding a lightning arrestor? Really enjoy seeing your work progress - thank you for the youtubes!
I think that guy is price-gouging lol. As for the lighting arrestor comment - I'm interested, but don't know much about them. Is there one you would recommend? And would that be mounted in the combiner box or near the charge controller?
Yes. I use MIDNITE SOLAR SURGE PROTECTION DEVICE 300VDC AND 120/240 VAC (example pic - www.altestore.com/store/enclosures-electrical-safety/lightning-protection/midnite-solar-surge-protection-device-300vdc-and-120240-vac-p9042/ ) They have a 3/4? pipe thread base - like a conduit connection. Make a hole in the combiner box and wire to the + and - (combined) wiring and grnd. The example above is outdoor quality - I believe its preferred at the combiner box (near the lightning strike) to block a surge going down the wiring into your other stuff. I learned that this protects both the + and - wiring because lightning could go down either wire as lightning doesn't care about current flow direction :)
Shade. Is it possible using a combiner box that I could have one array in one part of my yard, and another array quite a distance away in another part of my yard, and if one of the arrays gets substantially shaded that the output from the unshaded array would not be impacted?
... should there not be used some cable end sleeves on the solar cables? ( just to reach the 110% mark...)
last question. the solar array has mc 4 connectors with 12 awg wires both black and red. Ok. but can I use 10awg red and black wires with mc 4 connectors to connect to the combiner box ?
Thanks
Great work.. :-)
Is there a type of "combiner box" available that can primarily utilize power from solar panels (when sunlight is available) and supplement its output with grid power (as a secondary source) only when the solar current is insufficient to meet the required output?
So is each fuse control one panel? Because 2 panels in parallel would be 20amps with my panels.
Is it common practice to throw up blanket over the panels if you don't want any output or is that a no no?
Yes just wondering what size was the liquid sealed conduit pipe i am thinking it was 3/4 but not really for sure and I am a big fan and have learn so much on your Channel thank you for everything you do it really helps a lot because they are no classes in my area teaching how to do solar batteries inverters Etc so again thank you for everything you put on your Channel
It is 3/4 LFMC conduit. If you're unsure what size to use for your application, this is a good calculator www.southwire.com/calculator-conduit NEC states max of 40% fill for 3+ conductors :)
@@LithiumSolar thank you so much
I purchased the same Crimper some time back. Prior to that I was just using needle nose loaded with butt loads of bad words.
SAME. I was using needle nose then soldered, but sometimes it wouldn't fit in the connector due to solder - also resulting in butt loads of bad words. I wish I knew better back then.
@@LithiumSolar Yep, the right tool makes life a bunch smoother.
Ok, but if i want to disconnect pv + and pv - from inverter 1 and put it to inverter 2 , what is need to switch from home to diconnect all array pv or need to go box to disconnect all fuses?
Nice
did you plug the unused holes in the rubber plug with something?
Not yet. I have a 5th string to connect and a ground wire yet, which will leave me with one unused hole. I'll just stick a small piece of PV cable in to plug it.
how many kw was it made for a system?
I’m surprised it didn’t come with a shield for the bus bar for IP20 rating.
Also you’ll want an enclosure drain to prevent condensation accumulating and rusting out the bottom of the box. It will fill up until it spills into the flex and then flood the lower end and test the insulation until it shorts against the conduit.
I'm curious if you've seen this happen before? I've heard a lot of people mention condensation in conduit and I've yet to see it happen in any of my conduits (I have a lot of them). I'm not saying it's impossible, just... seems odd. Unless it's something that occurs over like 20 years or so?
@@LithiumSolar disaster is around 24/7 no matter what! Best way to avoid condensation is to check every now and then and dry up any signs of moisture. You will be surprised the kind of things I have found inside those boxes, spiders, all kinds of insect's, moisture, and rust. Even if they are new and built with the best materials I always do a routine maintenance on those boxes. Excellent set up, keep up with the good work! Kind regards from BC.
Nice video but is it ok with no negative fuse.
I have a 2-pole circuit breaker at the charge controller. Whether or not this box is ok (with a positive-only fuse) will depend on your local codes.
what is the size of the green wire? rookie questions I know
Do you need 3 To 1 Y Type MC4 Branch Solar connector if using a combiner box? THANKS, I have 6 panels...
No. The combiner box takes the place of the Y adapters. I don't like the Y adapters personally. It's very easy to accidentally overload the connectors or wires.
Instead of running panels in series, would it be beneficial to use a combiner so that all panels work at there best, and aren't affected by a panel being shaded? I only have 3 430 watt panels that I use with a bluetti ac 200max. I'm thinking if this is the case I'd maximize my charging.
The controllers I'm using require a minimum voltage of 60Vmp to run. Most MPPT controllers will have a minimum voltage exceeding that of a single panel.
I wonder if there is a requierment to connect the metal of that conduit to ground...???
The conduit is bonded to the metal case. The lock ring that is screwed down on the conduit fitting has teeth that bite in to the box metal (through the paint). They do make some rings that also have a ground wire terminal on them - up to your local codes if that's required.
Hmm never made a later video about the frames EGC to the busbar connection or the inverter end of the EGC ?
Nope. This was connected to an isolated controller so I never had it grounded. It's since been replaced and grounded properly now. I would suggest following all electrical codes/requirements for your area!
How did you determine the size of the wire for the combiner box? Thanks
I always reference the NEC code, section 310.16 as a starting point. There is more that goes in to it beyond this though, such as length of wire, bundling, etc. You can find the table on Google fairly easily.
Our Pack Rats must like the taste of the wire. You have to use PVC to armor the wire.
Could you visit Corridor Cast some time ?
Is it a good habit to solder the wire at the crimped part to get a better electrical connection?
Absolutely not! It may sound like a good idea, but you're creating a weak point on the wire that's subject to breaking if/when it flexes. Additionally, you're filling the terminal with a metal that softens and melts at a very low temperature (ie if the connection starts to heat up for whatever reason). A proper crimp is superior to solder in this application.
@@LithiumSolar thanks for that valuable tip.
If you can easily feed your wire through your conduit, don't cut the excess, just push it to the other end, so you will have on long piece of excess wire instead of two shorter pieces.
HOW MANY PANELS 4 TOTAL, EIGHT WIRES?
Great video. Might be good to point out that these are knock-off MC4 connectors that are shown and shouldn't be cross-mated with look-alikes, including true (Staubli) Multi-Contact MC4s.
They are not, nor do they claim to be, Staubli-brand.
Can i use it for wind turbine and solar
I'm not familiar with the requirements of wind power.
mc4 metal contact area between m/fm is very small -
they were designed Long ago when panel output was a few watts
30A
Is it possible to turn around the bus bar on the right?
I think it would be easier if you loop the charge controller wire, and connect all the solar panel wires from the bottom.
Daves Tech no top penetrations on outdoor NEMA 4 enclosures
Yes, the bar could have been turned around. It's just held in by a pair of phillips screws. I suppose that would have made it easier, hadn't thought of that.
And yes, no top penetrations. I don't even like side connections (have one on another unrelated box).
@@davestech6357 Top connections are risky for being water proof. If you have even the smallest leak then in top connections water will drip inside, while in bottom its unlikely.
So should the combiner box be close to your panels as opposed to next to your inverter. So then you run a thicker 6 ga wire to the house, eh?
Typically they're installed at the solar panels, then one set of conductors run back to the inverter. However, please make sure to check and follow your local codes/requirements.
Were is the link to that fancy tool to disconnect the MC4?
The crimp tool kit includes 2 of the MC4 connect/disconnect tools watts247.com/product/mc4-solar-crimping-tool-kit-crimper-for-2-5-6-0mm2-solar-panel-pv-connectors-cable/?wpam_id=97
@@LithiumSolar okay, I saw that but the tool you were talking about to replace the needle nose pliers I didn't see. Is that the same thing as what is in the spine of that kit?
@@awesomedee5421 Yes, it's the same thing. In reference to the tool shown in the spine of the kit, the round part is for tightening the nut down where the wire goes in to the connector when splicing new connectors on. The two points on the other end are the disconnect tool. They will go over the MC4 and press the two tabs in for removal.
DO I NEED 2 HOFFMAN BOXES FOR 10 100WATT PANELS?
Two questions:
1) What gauge grounding wire did you use coming from the array?
2) Did you also run ground wire from the ground bus bar to a grounding rod in the ground? And if so what was the gauge ground wire to that ground rod?
You should ground it in accordance with the code requirements in your area.
@@LithiumSolar right but I was still curious what gauge ground wire you used and if you installed a ground rod and wire to the combiner as well
6 from panels to combiner, 10 from combiner back to shed.
@@LithiumSolar gotcha, thanks
Can you help me understand why you needed a combiner box for six panels? I would assume for that small of an array, you would just make 1 string and only have 2 wires to deal with at the end anyway.
I have 15 panels. My charge controller (like most off-grid controllers) is limited to 150Voc input. Because of this, I can only wire 3 of the panels in series before I risk exceeding 150Voc. So I have 5 strings I need to combine.
@@LithiumSolar Ahhh, I misunderstood. That would do it then. Most of the UL listed Hybrid converters I see go up into the 480 -580v range. But yes, 150v would limit you. Thanks for the quick response!
@@rustusandroid My system is 100% off-grid. A hybrid system is still technically grid-tie and requires piles of permits, contracts, and approvals :)
@@LithiumSolar True that. Maybe I should watch more of your videos before I start running my mouth :)
Couldt you make a solar generator, thats in a solar panel? Wouldt be very happy, i love your videos
Shouldn’t the fuse busbar be on the other side? The left side was hot when you dropped the fuse in..
The fuse doesn't make contact on either end until you close the fuse holder.
083120/0104pst Thanks once again for the meticulous procedure. stay safe and 73s...
How many panels in each string, and what are the values of the panels, Voc, Vmp, Imp, Isc..??? Are they 12v or 24v panels, wattage each panel...???
I think you can gleen the information I'm looking for...
I'm not going to go through and collect this information. I'm not sure what you're looking for, but the label on the inside of the box lists out the specifications for the enclosure.
@@LithiumSolar I wasn't referring to the enclosure...and by me listing the info I requested, and you not being "sure" as to what I'm looking for tells me that you have 1) no idea what you're doing, 2) no business guiding other people...
@@wipatriot510 This video is nearly 4 years old. How do you expect me to spout off those numbers and calculations nearly 4 years later? I'm not going to run around like a puppy and gather this because some random commenter asks. Additionally, this box isn't even installed anymore. You should be following your local codes, requirements, and regulations, not relying on a TH-cam video.
@@LithiumSolar It's BASIC information...and if you're not here to make reliable content, then you shouldn't be on youtube at all...
pound a 6'-8' bar into the ground and put a mechanical clamp (elect supply store) or you can Cad Weld/Exothermic, and attach your ground wire from that to your box buss bar. Your resistance should have 5 ohms or less - no more if possible = All good.
I do have an 8ft ground rod already pounded in. I guess I'm just not sure what gauge wire and proper clamps to use. You mentioned max 5 ohms, are you measuring that between the solar panel frame and the grounding rod?
Yea, I am working on my install and bought a grounding rod, not sure where to measure the resistance
@@BobHannent anywhere along the ground works the same. 5 ohms or less is a pass for any electrician. 0 is the best. I am a CM.
@@BobHannent code says 8' rod but 6' works what doesn't work it hitting a rock 3' down then cutting it off so it looks like 8' lol
@@BobHannent i have built 100's of telecom cell sites rooftop and dirt(greenfield). .
Quick question, is 90VDC really dangerous? If I'm not mistaken, you can't even feel it. 90VAC is another story
Yes. I can feel 48V and it stings. I don't want to know what 90V feels like...
Vdc is even worst
Generally anything 50 volts or higher is considered to be capable of killing you.
I am a beginner in this area so bear with my foolish questions. First, why did you use 6 awg red wire for the positive and 12 awg black for the negative? should you not use 6 awg black wire?
Both red and black are 6 Awg.
@@LithiumSolar thanks for the reply
@@LithiumSolar size of the green wire? Thanks
sorry saw my mistake after watching video 3 times just to be sure
Just my luck the little screw would fall down into the conduit.
next time tape all conductors together and pull it in 1 shot it's a lot easier
I would have done it that way if I were pulling rather than pushing it through. I figured it would have been too thick and stiff to get around the 90 bends, but maybe not.
😁✌🖖👌👍😎
Why not connect all the wires onto the breakers then set breaker in place on the rail?? Way easier!!!
That sounds more difficult to me. You're welcome to do yours how you see fit 🙂
Measure twice, cut once
I've seen a lot of rookie engineer's making the most stupid mistakes working around boxes like this, the worst is that they open a "company" offering their services very very cheap! That has cost us, the professionals in this field the loss of revenue, but, many times they call us back to fix the stupidities done by the rookies! 40 years of experience you don't get it even if you go to the most prestigious universities or technical garage schools. Electricity is deadly in many ways, either DC or AC. I never take short cuts, I know about many people being killed because a simple mistake. Take it seriously! Electricity can kill!
Thanks a lot
you did not show out put voltage
better show that
Why do people not cut ends off cable ties.....shreek.
I do cut all ends off cable ties.
Try to stay away from those screws you're using on the conduit. They're drywall screws and they rust and are very brittle. Tighten them too hard and they snap off.
They are exterior decking screws :)
@@LithiumSolar Yeah, not really the best choice. The bugle head is wrong for this application. Just saying. Otherwise, great job.
@@alext8828 Thanks. I'm not overly-familiar with hardware like this. I use deck screws pretty much everywhere. Is there a specific kind you would recommend?
@@LithiumSolar A wood screw with a flat bottom to press down with its entire surface rather than a bugle head that tries to displace material as it goes in. Excellent job.
@@LithiumSolar Your local big box store will have hex washer head "sheet metal" screws in stainless steel to size 14 (1/4") in various lengths. "Lag screws" in still larger diameters.