Photovoltaic system: How many kWp are enough for a house?

As it looks, I cannot send private messages ... they probably end up in nowhere. I recently read about this issue with ?! ‍

As it looks, I can’t send private messages ... they probably end up in the void. I recently read about this issue with ?! ‍

Maybe email?
[E-Mail]Lin0r@gmx.de[/E-Mail]

so.. we have increased the system to 6.84kWp. More probably wouldn't fit on the roof unless we increase the power per module. Now there are 19 modules, without storage. 1kWp = €1345. If I did everything right.

Hi 1. Since from 7kWp you would otherwise be forced to get a smart meter, which costs more, a system just under 7kWp is good because you avoid this obligation 2. The costs per kWp seem a bit high to me. It is probably due to the small system size and the high-performance modules. But this can be judged much better in the already mentioned forum. There you can also request alternative offers. I planned and ordered my photovoltaic system there myself 3. The air heat pump will indeed increase your consumption, but the photovoltaic system will cover about 35% of your total energy demand (heating + household electricity). If you know your heating load and the heat pump that will be installed, you can estimate the future demand for purchased electricity quite well. So bring on the values. I myself started with a 7kWp at about 6.5kW heating load. So I can estimate quite well what will end up with you in the end. 4. Forgoing storage is exactly right. Unless you upgrade your house to KfW40 standard. This is extremely attractive with the current KfW subsidy. The additional costs for you will with high certainty be more than covered by the additional subsidy. Regards Niko

We have 7.5 kWp on the roof, plus a 7.7 kW storage. The heat pump heats the house during the day when there is surplus electricity (screed as a buffer) and raises the hot water temperature. The storage lasts until the next morning. Everyone has a different opinion: do everything fully; do up to 9.9 kWp; do without storage; etc...

How big is the house? What is your annual electricity consumption?

So we have 28 modules, a total of 8.68 kWp on a pure south-facing roof. Currently, power is produced until about 8:30 PM. From 6:45 PM it drops to below 1000 watts. Our house consumes according to the smart meter approximately around 250-300 watts when looking at the live data (in the meantime, the hot water system kicks in with a consumption of 4 kW). From 7 PM the house draws power from the photovoltaic system and the storage.

Now comes the interesting part: since the day before yesterday we have a BYD storage with 6.4 kW installed. In the morning, depending on evening usage, the storage is still 30% (yesterday), 20% (today) full.

The storage is sufficient for normal household consumption (at least currently). From October (or rather the start of the heating season) until the end of February, I do not expect that we will remain self-sufficient.

Furthermore, I have a small electric car and if I consider that I can charge it at home from 5 PM (estimated 7 kW need to be charged), after Corona / end of home office the storage definitely will not be able to supply the house until the photovoltaic system starts up again in the morning. Fortunately, the BYD storage can be expanded with 4 more 1.28 kW modules.

Just a report from my experience for those interested

...and if I have mixed up kW or kWh, please forgive me. I think it is still understandable!

P.S. The dehumidifier in the basement is currently running at full power on the screenshot.
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interesting report. My photovoltaic system is oriented east/west. The yield is slightly less than with a perfect south orientation. However, the electricity comes from the roof a bit earlier. Since I also have a Kostal inverter, I am considering retrofitting a BYD battery. There is even a subsidy from the state, but then I would only be allowed to feed in a maximum of 50%, and that ruins the return :-(