Pumpernickel1
2022-01-03 11:55:06
- #1
So we have 2 meters and 2 tariffs. But we don’t have photovoltaics yet and I decided to just test it out. I didn’t know before how much heating energy we actually consume.
As expected, it seems very tight whether it’s worth it – and that’s already without photovoltaics.
I would strongly advise against it with photovoltaics, because then you inevitably reduce the self-consumption, and that is the "most valuable self-produced electricity". At least, I am not aware of any way to assign the same photovoltaics to 2 power lines for self-consumption. You would probably have to decide in which line you want to consume the generated electricity. You can attach it to the heat pump’s consumption (which is nonsense because photovoltaics produce a lot in summer, but the heat pump needs a lot in winter) or to the household electricity (which means that in summer and possibly even in winter your household electricity is completely covered by photovoltaics, but the heat pump is operated 100% from your heat pump electricity. I consider that too risky because you might miss some nice winter sun hours that could support the heat pump’s self-consumption – but that also depends on which photovoltaics you have. If it only produces yields from spring to autumn, then you can run the heat pump separately – but we have a 50° roof facing south, so I expect some yield in winter).
As a last option, you could also "separate" your photovoltaics. That means one inverter with one part of the system for the heat pump’s self-consumption and the other for household electricity. No idea if there are possibilities to make the split more flexible (like almost everything in winter for the heat pump and in summer 20% for the heat pump and the rest for household electricity). But the energy supplier would also have to cooperate to install 2 bi-directional meters. I think they exclude that anyway (at least for heat pump electricity they probably won’t agree?!).
And as I said, even for us the second meter is hardly worthwhile (I can only say precisely in 5 months. Our (low) basic fees for the second meter still almost offset the cheaper kWh consumption. But again, that depends on how much heating output you produce per year and with which annual performance factor. But considering the efficiency and comfort losses of the heat pump, and that it sometimes hits the utility lockout, I think that from 1.7. we will only have one meter and then calmly approach the photovoltaic topic.
Thank you for your detailed contribution. That helped me.
I roughly calculated it. A second meter will cost us between €800-1000. The monthly difference between one and two tariffs is about €15–20 (in the best case. But even here the heat pump tariff can steadily increase, thus diminishing the price advantage over the years). Since we want to install a photovoltaic system anyway in the next 2–3 years, we tend toward the solution with one electricity meter.
Our electrician just said that the space for a second meter might be needed sometime (you never know what the future brings) and therefore he would install a second meter. But we will waive that. Thank you.