Offer for photovoltaic system including storage - Storage yes/no?

have you read and understood my calculations regarding the memories? What do your calculations look like?

have you read and understood my calculations about the storage systems? What do your calculations look like?

Yes. But you only assume a lifespan of 10 years for the storage system and not rising electricity prices, instead a permanent saving of 20 cents. Of course, that is a very one-sided calculation. However, there are also providers who guarantee 70% storage capacity up to 20 years, naturally for an additional charge. They would probably hardly do that if they didn't know whether it would last that long. As I said, I can calculate both variants well or poorly, depending on which values I use for the variables. If you calculate the average return of an ETF World portfolio instead, then neither variant is profitable. At most, the balcony power plant is profitable.

Then just calculate with 20-25% self-consumption. What does that give you?

Of course, the system without a storage device somehow pays off through self-consumption.
The question then is whether it really makes sense to fully cover the roof.
The bigger the system, the lower the share of self-consumption. While the first module probably delivers 100% self-consumption, the last module may only bring 2-3% additional self-consumption.

I have a hipped roof and then have the choice between 2 sides, 3 sides, or 4 sides.
Bigger then also means more effort for scaffolding and an additional inverter, etc.
Fully covering it also means that I am over 10 kWp, so the feed-in tariff is even lower.
"Fully covering," might indeed deliver the absolute best yield, but from a cost-benefit perspective, in my view, it may not be optimal.

Yes. But you’re only assuming a 10-year lifespan for the storage.

You just have to make some assumptions.
10 years is a value you often find; rarely is there a longer warranty.
But you can certainly do the calculation again with 12 or 15 years.

and not rising electricity prices, but a permanent savings of 20 cents.

Yes, I had written that it should balance out with the financing costs.
Both are about 3%, but it's also one of those crystal ball parameters.

But there are also providers who guarantee 70% storage volume for up to 20 years, naturally for an extra charge. They probably wouldn’t do that if they didn’t know whether it would last that long.

The fact that they aren’t so sure about it is clearly shown by the surcharge!

As I said, I can calculate both variants well and badly depending on the values I use for the variables.

You may be right, but with realistic assumptions you almost always come to the conclusion that storage in a photovoltaic system worsens the overall profitability compared to a photovoltaic system without storage.
And, as mentioned, you should always consider that it harms the environment.

If you compare it to the average return of an ETF world portfolio, then neither variant pays off. At most the balcony power plant.

That’s not a meaningful comparison.
Completely different asset classes, completely different risks.

Of course, the system without storage pays off somehow through self-consumption.
The question then is whether it makes sense to really fully cover the roof.
The bigger the system, the lower the share of self-consumption. While the first module probably delivers 100% self-consumption, the last module perhaps only brings 2-3% additional self-consumption.

There are quite good calculators and simulations for that.
You also have to consider that every additional module is cheaper.
You only need the connection, the inverter, etc. once.

“Fully covering” may deliver the absolute best yield, but from a cost-benefit ratio, in my view, it’s probably not optimal.

The best percentage yield certainly comes from the self-installed balcony power plant.
The best absolute yield certainly comes from the full roof (without storage).
Most seem to have the most fun here with a full roof and full storage.

You just have to make a few assumptions.
10 years is a value you often find; rarely is a longer warranty given.
But feel free to do the calculation again with 12 or 15 years.

That's right, there is a 10-year warranty. After that, it could break (that would, of course, be the worst case) or it might last another 10 years and lose some performance.
Possibly only one module might break.

Yes, I wrote that this should balance out with the financing costs.
Both are around 3%, but it’s also one of those crystal ball parameters.

In my opinion, it only apparently balances out because you assume both at maybe 3%. While the interest effect decreases over the term since the repayments are offset as amortization, the effect of price increases continuously grows and, since the remuneration remains constant, even disproportionately so. Based on the difference between the electricity price and the payback, you would then have an effect of about 3.8% instead of 3%, if I didn’t make a mistake. After 20 years, the electricity price would not be 30 cents but 52 cents, and the difference would be 44 cents instead of 22 cents.
But this is just a rough estimate; maybe I have a thinking error in there.

That is not a meaningful comparison.
Completely different asset classes, completely different risk.

That may be true that it is a different asset class, but the investment period is roughly the same. That would at least be what I would alternatively do with the money.

There are quite good calculators and simulations for that.
You also have to consider that every additional module is cheaper.
You only need the connection, the inverter, etc., once.

That may apply to the last module. But in between, you have additional costs (I think those are called step-fixed costs), e.g., for a second inverter or scaffolding for the fourth side.

The best percentage return certainly comes from the self-installed balcony power plant.
The best absolute return certainly comes from the full roof (without storage).
Most seem to have the most fun here with a full roof and full storage.

I’m exactly wavering in between :)

We have now lived in the house for 10 years. So far, I preferred the special repayment with a guaranteed 3% saving rather than a possible 3% return from the photovoltaic system.
But the subject is finally coming to an end, as the house is almost paid off. Money in abundance to pay for the full roof with the big storage out of petty cash is also not there yet. I am approaching 50. We have a 20-year cycle. Whether one would still deal with the topic again at 70 years old, one does not currently know.

However, here costs of 10,000 euros for a 10 kW storage system are assumed. In reality, it only costs 4,000 euros. This absolutely justifies the storage system.

Likewise, there are people who pay for their PV system, with or without storage, out of pocket. Just like myself. Financing costs do not play any role in this case.

On the contrary. It brings me a 10 percent return p.a. on my invested capital. Despite the storage system.