Consultation for photovoltaic systems

So if we now have a sunny day in April or May, the photovoltaic system first charges up.
The storage should of course be charged primarily. It is full in 2 hours.

Photovoltaic yield is from 8:00 a.m. to 4:00 p.m. So on a sunny day ideally 50 kWh. (7kW x 8 hours)
Everything must happen during this time. Doing laundry and washing dishes, cooking, vacuuming, etc.

The next day it rains. Then the storage kicks in for the base load. We don’t need laundry and dishwasher every day.
According to my calculations, the 7.2 kWp photovoltaic system should be optimal for the 10 kW storage. If it turns out not to be enough, a few more modules just have to go on the roof.

If I think about it offhand what happens with systems under 10 kWp in the winter in the photovoltaic forum... they would need several days to fill the storage. In the evening it’s empty after 1-2 hours because the heat pump alone is already a big consumer.
If you also run the dryer during the day and have 2 days of home office, then it’s even worse.
I haven’t had any experience with this yet, but looking at the yields like that, you will probably use your storage rather little in winter and in summer you fully charge it (including charge-discharge losses) but won’t be able to empty it anymore.
I had considered connecting a 5 kW storage with about 12 kWp here. But even that simply isn’t worth it (we have a heat pump), since it never gets full in the crucial season.

So it's true that I can't empty the battery at night. But I don't have to.

My calculation is from mid-November to mid-February with zero yield, so complete grid usage. It doesn't matter how big the system is.

I don't have a heat pump or an electric car and I don't plan to. I once bought my old oil heater used for 20 euros. It still works perfectly and has great values. So I can still buy a lot of heating oil. I only need 1000 liters per year.

The rest is done by the kitchen stove and when it gets really cold I crank up the fireplace in the living room. It has 21 kW. At minus 20 degrees I turn off the heating.

However, I am planning a terrace roof, but with glass sliding elements. It will certainly need an air conditioning unit. But you only need that when the sun shines in summer. Well, if there is enough electricity, consumers will be found.

And as already said, since I built the system myself, the construction costs are still reasonable. Altogether the project including a 10 kW battery costs me less than 11,000 euros. Many homeowners pay twice as much and without a battery. Then it’s of course not worth it.

And in combination with a backup box, I am capable of emergency power. That gets me through a few hours or days.

Since many people here rely on some kind of calculators and make forecasts into the future, here are our real values from last year. Known to be a very bad year for photovoltaic systems, but real numbers without any asterisks notes.

Photovoltaics: 28.35kWp
Orientation East, West, West
Storage 10.2kWh

229 full cycles
15.0% storage losses in/out
64.7% self-sufficiency
30.9% self-consumption rate

229 full cycles

Wow. May I ask what drains your memory so often?

Since many here trust some computers and make forecasts about the future...

Actually, only our expert for everything does that here. The rest just try to talk him out of it ;)

There are a few small optimizations. But the problem with full cycles is more about filling rather than emptying. Here, the large system and the E/W orientation help.

Heat pump, cooling, hot water, and a very high household electricity consumption (the cause of which I honestly haven’t really found yet) also draw quite a bit from the storage in summer.

Autonomy is certainly not very meaningful, as there are hardly any sunny days in autumn and the roof is covered with snow and 0 yield for several weeks at the beginning of the year.