ᐅ Is it practical to install a photovoltaic system on the west or east side of a building?

That might help you today when you sign the contract, but it won’t really make a difference. Since the vast majority of people can do the math, I don’t really believe this concept will catch on. You’re unnecessarily locking yourself into a single provider.

The best approach is to use as much of your own generated electricity as possible and feed the surplus back into the grid—that’s it. No extra contracts, commitments, or provider restrictions.

ludwig88sta schrieb:

Of course, nothing is actually "stored" this way, but you effectively get the electricity that you couldn’t use during the day in summer back over the winter for free. That’s why it’s considered a kind of "virtual storage." Obviously, you’re always tied to the electricity supplier, but it’s better than nothing (considering the low feed-in tariff).

Why is a "cloud storage electricity contract" better for me AND for the provider than if I feed electricity into the grid myself and buy the electricity I need regularly from an electricity supplier of my choice?

I admit I haven’t even read the cloud contracts, nor did I buy the photovoltaic system from providers who handed me flyers about this.

From a tax perspective, cloud schemes complicate the already absurdly complex process so much that standard software for photovoltaic tax management is no longer sufficient.

kaho674 schrieb:

Please forgive me if I don’t fully understand the financial models, but do I get it right that depending on the size, it can even be profitable if you finance it completely?

With an east/west/south orientation, a 10 kWp system (about 50m² (540 ft²)) generates roughly 8,500 kWh per year.

That results in about €850 in revenue if you sell the electricity instead of using it yourself.
By using the electricity yourself, you can increase the annual income to around €1,100 per year, potentially a bit more with rising electricity prices.

Additional costs:
- €50–100 insurance
- €100 reserve fund for repairs
- €50 VAT on self-consumption during the first 5 years, then 0€ afterward
- some degradation of the modules over time
- possibly taxes and interest

A 10 kWp system should cost between €9,000 and €13,000 net.

From there, you can calculate everything else yourself. The return mainly depends on the purchase price of the photovoltaic system, as you can see for example with guckguck. Without financing, I only break even after about 12 years.

For a still relatively short period, feeding electricity back into the grid remains worthwhile. What matters is the date the system is registered. The feed-in tariff decreases every month. For systems under 10 kWp registered in September 2019, the tariff was still 10.73¢ / kWh; by January 2020, it was already 10.27¢ / kWh—a 5% drop in just four months. This trend continues until there is no longer a legally fixed feed-in tariff.

Prices for the systems continue to fall—you can buy a heat pump installed as a private individual for about €1,000.
Now, a calculation without subsidies at an electricity price of 30¢ per kWh:

Household consumption: 5000 kWh
System (east-west orientation): 6000 kWp
Annual production: 5000 kWh
Self-consumption from the system: 3500 kWh

System cost: €6000
Savings per kWh self-consumed: 20¢
Annual savings from self-consumption: 3500 × 0.20 = €700
Payback period < 9 years

Without a feed-in tariff, system sizing based on self-consumption is crucial. A much larger system only slightly increases the proportion of self-consumed energy and then becomes uneconomical.
The share of self-consumption can only be increased by a storage solution. This is where hot water storage, batteries, etc., come into play.

If you buy the system above with a battery storage, for example, 2.4 kWh, it costs about €7500 including a different inverter. This raises self-consumption to 3850 kWh (which corresponds to approximately 150–180 charging cycles per year, depending on degradation).
System cost: €7500
Savings per kWh self-consumed: 20¢
Annual savings from self-consumption: 3850 × 0.20 = €770
Payback period < 10 years

The “bets” on whether this is worthwhile are based on these assumptions:
1. How will electricity prices develop? — The higher the assumed increase, the more worthwhile the battery becomes
2. How many charge cycles are achieved per year? — Some estimate under 100 cycles, meaning it never pays off; others measure over 200 per year, which is apparently the main point of debate
3. Assumptions about battery durability

If you don’t view photovoltaics purely as a financial product but also as part of shaping the house, you can trade payback time for aesthetics and increased property value. After all, facade and garden design are often selected based on aesthetics rather than minimal budget. There are even people who buy cars without ever thinking about payback.

Long story short, as of today this is very cost-effective, and you are guaranteed to receive the feed-in tariff for 20 years. Besides, you can’t get a small system for that money.

The rest is pure speculation; no one knows what the future holds.

Bookstar schrieb:

Come on. The DAX averages a 14% annual return over such a period. You might as well forget about your panels on the cabin, which will end up as special waste later.

Photovoltaic systems are not profitable enough. It’s fine that there are enthusiasts and people who find the technology cool. But from a return perspective, it’s not worthwhile.

A 14% return on the DAX was possible if you timed the entry well after the last crisis. Over the long term, the average is 8%!
Additionally, there is market risk involved. With photovoltaic systems, the income is guaranteed. Of course, there can be losses, but these can be insured for a relatively small amount.

Photovoltaic systems are profitable!