Photovoltaic planning - possible retrofitting of battery storage

How do you plan a photovoltaic system that may later be equipped with a battery storage if rising electricity prices and falling battery prices make it economically viable?

My suggestion (based on many years of experience in another industry that has been intensively dealing with electric storage technology for some time): option 4 - forget storage. The hope for falling prices will not be fulfilled. With permanently increasing demand, which will be driven by the transport sector alone, we will never see significantly decreasing prices.

Regards

Option 4 - Forget storage.

I would agree with that.

The hope for falling prices will not be fulfilled. With continuously rising demand, ensured by the transport sector alone, we will never see significantly declining prices.

However, the experience (and studies) of the past ~20 years contradict this. The price is continuously and quite rapidly falling. And this is inversely proportional to the increase in sold electric cars.

As far as prices are concerned, I believe that you both are right and just talking past each other. Surely, technological development will gradually lower production costs. However, the closer we get to a profitability limit, the steeper the demand will rise, which may not be able to be met in the short term by production capacities. Consequence: prices do not fall as quickly because the order books are full and the margin is increased. That is exactly what we see with construction costs since interest rates have been so low.

As for the prices, I believe both of you are right and just talking past each other. Surely, technological development will gradually reduce production costs. But the closer we get to a profitability limit, the steeper the demand will rise, which then possibly cannot be met by production capacities in the short term. The consequence: prices do not fall as quickly because order books are full and the margin increases. That’s exactly what we see with construction costs since interest rates have been so low.

You couldn’t summarize it better. That’s exactly my assessment. Thanks.

Regards

Had calculated that quite often already... But it only pays off if just barely. I also calculated pessimistically - realistically, but still.

By now I would say a system size optimized for consumption of around 5 hours is "ideal."
Best if the system only draws as much as is permanently consumed. That would be minimal system costs and 100% self-consumption.
However, that is usually not high enough for the installation to be worthwhile just from the work alone.
But if you can store about 5 hours of the yield with a storage system, then maybe you have caught "peak times."
For example, charging in the morning and consuming at noon, charging in the afternoon and consuming in the evening + current feed-in.
That way it might be possible to realize the highest consumptions in energy consumption.
This way you could probably achieve the best price-performance ratio.

You have to calculate it exactly.

I had already calculated that several times...
But it only pays off if just barely. I also calculated pessimistically - realistically, but still.

I would like to see that calculation. There are plenty of calculation examples from buyers of these batteries. You still have the problem that in summer more electricity is produced than you need (and than fits in the battery) and in winter the battery is empty and production does not cover consumption.

In the end, they were all pretty much the same. Let's pessimistically assume 30% self-consumption without battery and optimistically 60% with battery.

This means 30% of consumption is additionally taken from the battery instead of the grid. The savings are about exactly 12.5 cents/kWh. Now, if we assume a household consumption of 4000 kWh, the battery brings us 4000 * 30% * €0.125 = €150 per year.

Over the battery lifetime of 20 years, that's €3000. It will take a long time before you get a sufficient battery for that. And then you only have your investment back, no profit.