this post was submitted on 16 Aug 2026
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Because of electricity costs in Germany it is a real no-Brainer but US has much cheaper electricity and I am not sure whether US plugs or electrical systems are up to the task tbh.
That will change when the panel paid for itself. When your electricity costs double, solar has a quicker ROI. But it will pay for itself really quickly, even in areas with cheap electricity
Let's do the maths quickly;
a full set of 2kW generator power and a 5kWh battery is sold in germanyfor around 1700€ right now. Let's assume 2000€ since we might need something to install them and maybe a power meter to only feed in as much as we need right now.
From my experience over the last two summers, such a system might generate some excess during the summer that might be lost in a personal sense. To compensate for that excess and conversion losses when (dis-) charging the battery, we'll assume 20% less generation than I've experienced over a 12 months period.
We pay 1000€/1kWp generation capacity. Each kWp generation capacity shall yield 800 kWh electricity each year, so our system will yield 1.600 kWh/a.
So if we currently pay 0,30 €/kWh, we will save 1600 kWh/a * 0,30 €/kWh = 480€/a. Which means our 2000€ investment will have itself paid off in 2000€ / (480€/a) = 4,17a or 4 years and 2 months.
If we assume an expected lifetime of 10 years, we get a generation cost of 2000€ / ((1600kWh/a) * 10a) = 0,125€/kWh
You might wanna keep in mind, that some of these systems provide some limited backup functionality to keep your fridge or other important devices powered during a blackout without any additional costs or maintenance as you might need for a generator backup.
That is not your bog-standard balcony solar installation and a 5kWh battery is way too much. You can get a 800W installation for 250-350€:
Let's say 300€. At 0,30€/kWh you reach your ROI at 1000kWh produced. Production depents on your locality, but it should be between 800-1100kWh for a 800W installation. So it takes approx. 1 year to get your investment back. The rest is pure profit. Yes, that might take a bit longer in practice. You are not using the full 800W at noon on workdays while you're away at work. You might not have perfekt alignment with the sun. And so on, but it is really quick.
If you are paying 0,15€/kWh, you might need 2 years to reach that ROI. That still is an awesome investment. Take a small sum of money. Invest one or two hours of work installing it. And if you are calculating with German prices and 10 years lifetime, you get 1000kWh a year @ 0,30€/kWh for 10 years = 3000€.
I ran fine with 2kWh storage and 1.6kWp, so yeah anything bigger than that might idle and therefore just delay breaking even.
That's why I would still recommend any battery. Not just to save some energy into the evening where electricity prices regularly spike in germany, but also to store in short-term when running a laundry machine on a so-so day.
Nonetheless, those small solar plants are likely always viable and I do regularly recommend them even if not asked :)