Install photovoltaic power storage yes or no?

We tell ourselves when building a house: there are the construction costs and the ongoing costs. We can afford the construction costs at the "now" point in time or not. That is, in the broadest sense, calculable. The ongoing costs are the unknown. During construction, we tried, as far as possible, to consider what will burden us more in the future. We could afford the construction costs that occurred, which is why we implemented them. The ongoing costs are, in our view, very variable and therefore unforeseeable. So we try, also here with the current status, to do as much as possible to reduce ongoing costs. Of course, there is also a good deal of idealism involved. Whether the tactic will pay off remains to be seen. Nevertheless, we feel good about the ground-source heat pump, photovoltaics, and so on. Storage is consciously left out but equally consciously planned and can be retrofitted at any time. I am curious whether we are right with this "idea."

When building a house, we say: there are the construction costs and the ongoing costs. We can afford the construction costs at the current stage or not. This is, broadly speaking, calculable. The ongoing costs are the unknown. During construction, we tried, as far as possible, to consider what will burden us more in the future. We were able to afford the construction costs that arose, which is why we implemented them. From our point of view, the ongoing costs are very volatile and therefore unpredictable. So we try, also based on the current situation, to do as much as possible to reduce ongoing costs.
Of course, there’s also quite a bit of idealism involved.
Whether the strategy will work out, we will see.
Nevertheless, we feel good about the heat pump, photovoltaics, and so on.
Storage is consciously excluded, but equally consciously planned and can be retrofitted at any time.
I’m curious whether we are right with this “idea.”

I proceeded the same way, but after last winter I realized that photovoltaics, kfw55, and a solid heat pump are not a cure-all if you don’t use the electricity when it is “free.” I drilled into my wife’s and of course my own head when it’s most sensible to use/load the dryer, washing machine, dishwasher, shower, cooking, baking, and car. Basically, I set up a consumption concept for all major consumers.
Sounds strange at first, but if you do basically the opposite, you shouldn’t be surprised if your self-sufficiency rate is below 20% and you waste electricity for 8 cents.

Anyone who buys a photovoltaic system based on the lowest price per kWp and at the same time discusses in the forum whether the window frames should be matte or glossy clearly lacks the ability to think about aesthetics and economy simultaneously. Great windows and hideously ugly panels on the roof? I’m laughing my head off. The statement that the share of self-consumption plays no economic role is ridiculous when the price of one kWh from the supplier is three times as high as the feed-in tariff. hmm – where is the kilowatt-hour probably used more economically? In terms of photovoltaics, those who cling to the old funding mentality clearly still have some blinders on.

Storage is worthwhile nowadays, even without subsidies. Two years ago, it was quite different. So go for it! A 40% grant is awesome.

But the storage must be very cheap for that. Typically, such subsidies come with strict limitations on injection. So look at the conditions very carefully and do the math.

Calculations with the storage are made with different assumptions. If you only calculate with sunshine hours, it looks like the left side of the illustration. If you also calculate with cloudy days, it can look like the right side. From this, an assumption about the cycles of the electricity storage arises. This assumption determines the calculated price of one kW from the electricity storage. So, it can be calculated both favorably and unfavorably.

(Source: HTW Berlin)

The funding is available at NBank. So it applies in Lower Saxony.