I took part in the Heatflex trial last year. I did not really notice any change in actual temps or thermal comfort during the trials. I also experimented with raising the LWT prior to octopus saving sessions and then dropping the LWT during the saving session this had the same effect no change in thermal comfort but the power usage was shifted and extra savings for me.
One element that I have noticed with many of these podcasts about heat pumps and the inter-related subjects is the lack of discussion about capital costs and the effective rate of return. All electro-mechanical equipment has a finite life and will therefore require replacemment at the then current price. Many of the discussions seem to assume that a high %age of the population will have the financial resources to implement the most efficient system/solution. Update: comment made before minute 38 so was before the comments about econmic fairness, this is one of the most fundamental elements with respect to mass effect of change of lifestyle.
Batteries are not a universal panacea; they are subject to efficiency constraints too. I have a V2G EV setup and the round-trip efficiency is around 81% at full charge/discharge rates; when you decrease the amount of energy you are charging or discharging with, the efficiency goes down, and I've measured the one-way efficiency as low as 66% for 730W, and that can still be useful but it does mean the input energy can be quite a bit more than the output energy. So there's a calculation to be done with a trade-off of efficiencies and that may be a fairly simple calculation but it probably varies on a case-by-case basis. I don't have a heat pump yet but that's something I'll be experimenting with when I do; I've had a survey done and apparently the heat loss is about 5kW for the house so it's probably going to be a fairly small heat pump. An efficiency curve of operation of V2G battery kit versus power level for charging and discharging is a question anyone should ask who is going for a system.
You don't need to do the whole 2-3 hour peak period to get a large grid benefit if you split a large population into 3-6 groups and do 30-60 mins per group. Next to no-one will notice a 30 min setback and only the worst insulated will notice an hour. The Daikin's have built in smart grid relay controls to support force on with room buffering and force off too. I have done 3 hour setbacks with no pre-heat on Agile, we do start to notice slight reduction in comfort in colder weather.
One other variable is the inverter power limit. During the peak, in a house that is fully electrified, it's possible to draw more power than the inverter(s) can deliver. Shutting down loads in that period will help avoid going out to the grid at peak.
I'm about to install a system with a large thermal store which will be heated to 80 deg + by a heat pump and immersions powered by PV power & from grid when cheap enough. Blended down for 100mm UFH in screed. Using NodeRed to control. There's no cheaper way of storing energy. 300l tank DT 65 = 23kWh storage, if you've got the space. Let's start pooling data. You don't need big long winded studies to validate simple ideas.
It might be that a system with a buffer tank would cope better with switching the heat pump off for a while. Also, it would be easy to move the hot water heat up period to avoid high demand times. Instinctively I think that a battery is a much better idea than changing the heat pump settings. The main thing is to have analogue signal or price per unit (rather than a simple on/off signal) going to each home. This would allow the home owner's smart controls to vary the demand just as much as needed using whatever tech it can control.
It's nice to have enough to cover that peak period 4-7 when the price jumps 10p. Alternatively or additionally you can boost the temp but .5C for one hour before to further reduce your demand at that time. This reduces the requirement for a battery, or increases the time the battery can be used for during the peak?
I took part in the Heatflex trial last year. I did not really notice any change in actual temps or thermal comfort during the trials. I also experimented with raising the LWT prior to octopus saving sessions and then dropping the LWT during the saving session this had the same effect no change in thermal comfort but the power usage was shifted and extra savings for me.
One element that I have noticed with many of these podcasts about heat pumps and the inter-related subjects is the lack of discussion about capital costs and the effective rate of return. All electro-mechanical equipment has a finite life and will therefore require replacemment at the then current price.
Many of the discussions seem to assume that a high %age of the population will have the financial resources to implement the most efficient system/solution.
Update: comment made before minute 38 so was before the comments about econmic fairness, this is one of the most fundamental elements with respect to mass effect of change of lifestyle.
We do this with cosy octopus already. House is well insulated and we top up if necessary. No buffer tank, which I think would be a good idea.
Lots of people have been doing it a long time. It doesn’t really pay off that much though as per our accompanying video
@HeatGeekUninsulated buffer tanks don’t hold energy to load shift
Batteries are not a universal panacea; they are subject to efficiency constraints too. I have a V2G EV setup and the round-trip efficiency is around 81% at full charge/discharge rates; when you decrease the amount of energy you are charging or discharging with, the efficiency goes down, and I've measured the one-way efficiency as low as 66% for 730W, and that can still be useful but it does mean the input energy can be quite a bit more than the output energy. So there's a calculation to be done with a trade-off of efficiencies and that may be a fairly simple calculation but it probably varies on a case-by-case basis. I don't have a heat pump yet but that's something I'll be experimenting with when I do; I've had a survey done and apparently the heat loss is about 5kW for the house so it's probably going to be a fairly small heat pump.
An efficiency curve of operation of V2G battery kit versus power level for charging and discharging is a question anyone should ask who is going for a system.
That’s really helpful Thankyou!!!
You don't need to do the whole 2-3 hour peak period to get a large grid benefit if you split a large population into 3-6 groups and do 30-60 mins per group. Next to no-one will notice a 30 min setback and only the worst insulated will notice an hour. The Daikin's have built in smart grid relay controls to support force on with room buffering and force off too. I have done 3 hour setbacks with no pre-heat on Agile, we do start to notice slight reduction in comfort in colder weather.
One other variable is the inverter power limit. During the peak, in a house that is fully electrified, it's possible to draw more power than the inverter(s) can deliver. Shutting down loads in that period will help avoid going out to the grid at peak.
I'm about to install a system with a large thermal store which will be heated to 80 deg + by a heat pump and immersions powered by PV power & from grid when cheap enough. Blended down for 100mm UFH in screed. Using NodeRed to control. There's no cheaper way of storing energy.
300l tank DT 65 = 23kWh storage, if you've got the space.
Let's start pooling data. You don't need big long winded studies to validate simple ideas.
The important thing is paying people for that flex and giving people the choice
It might be that a system with a buffer tank would cope better with switching the heat pump off for a while. Also, it would be easy to move the hot water heat up period to avoid high demand times. Instinctively I think that a battery is a much better idea than changing the heat pump settings.
The main thing is to have analogue signal or price per unit (rather than a simple on/off signal) going to each home. This would allow the home owner's smart controls to vary the demand just as much as needed using whatever tech it can control.
Buffers don’t hold enough energy to load shift
So I presume for heat pumps we should all have batteries to help draw at peek times.
It's nice to have enough to cover that peak period 4-7 when the price jumps 10p. Alternatively or additionally you can boost the temp but .5C for one hour before to further reduce your demand at that time. This reduces the requirement for a battery, or increases the time the battery can be used for during the peak?