Inverter
Old inverters cannot charge a battery. An AC-coupled battery brings its own inverter and is easier to retrofit. A DC-coupled one needs a new hybrid inverter.
Source: Verbraucherzentrale (consumer advice centre): batteries
Battery storage
Add a battery.Honestly calculated.
For your existing solar system, even if another company built it. We check the inverter and meter cabinet, work out your case and tell you if a battery does not pay off.
Request a battery check Or call us directly: 089 200 679 23
When it pays off
Three numbers decide
A battery moves solar power from midday to the evening. Whether that pays off for your system depends on three numbers.
- 01
Your evening consumption
A battery only helps if you use power while the sun is down. It need not be bigger than what you use between evening and morning.
- 02
Your system’s surplus
Only the power you do not use during the day can fill it. The amount you feed in is on your yearly bill or in your inverter’s app.
- 03
Your feed-in tariff
Every kilowatt hour you store is one you do not feed in. With a high fixed tariff little is left over; once the tariff ends, much more.
From our work: If you have a system from around 2015 with a good feed-in tariff, a battery rarely pays off financially. Some people want one anyway, for example for backup power. That is a different decision.
What we check · As of 26 October 2026
What adding a battery involves
On older systems the job is often bigger than expected. That is why we look at these four things first.
Meter cabinet
Since 2024 the grid operator must be able to control batteries that charge at more than 4.2 kW (§ 14a EnWG). That needs room in the meter cabinet, usually including an APZ panel. Old cabinets often lack it.
Space and cable route
The battery needs a suitable spot, ideally close to the inverter. The longer the route between them, the bigger the job.
Backup power
Some batteries keep one socket running in a power cut, others the whole house. This often costs extra and does not work with every appliance. If you want backup power, it is written into the quote.
Source: Verbraucherzentrale (consumer advice centre): batteries
After installation we register the battery in the Marktstammdatenregister, the national register, just like your solar system. Source: Marktstammdatenregister: who must register
Built by another company?
We add batteries to other installers’ systems too
Because we do not know your system, we check it carefully first: the inverter, the meter cabinet and the route to the battery’s spot. Then you know what the job really involves and what it costs.
If a new inverter is due anyway, we can plan more modules, a wallbox or the heat pump connection at the same time.
Brands we install include SolarEdgeBYDFroniusSMASigenergyAXIstorage
How the battery check works
- 01
Details and photos
Your system’s details plus three photos: the meter cabinet open, the inverter with its type plate, and the spot for the battery. Most of it is on your bills and the type plate.
- 02
Check
We look at your details and photos. If needed, we come by.
- 03
Quote with the numbers
With the total price and the savings we expect. If the battery does not pay off, we say so.
- 04
Installation and registration
We install the battery and register it in the Marktstammdatenregister.
Frequently asked questions
Does a battery pay off for my existing system?
That depends on your evening consumption, your system’s surplus and its feed-in tariff. With a high fixed tariff it rarely pays off; once the tariff ends, often more so. We work it out for your case.
How big should the battery be?
The consumer advice centre suggests about 1.5 kWh of storage per 1,000 kWh of yearly consumption. A bigger battery adds hardly any self-consumption.
Do you add batteries to systems other companies built?
Yes. We check the inverter, the meter cabinet and the space for the battery first, so you know what the job involves.
Do I need a new inverter?
Not necessarily. An AC-coupled battery brings its own. If your inverter is old anyway, a new hybrid inverter often makes sense.
Does the battery supply power in a power cut?
Only if it is built for it. Some keep one socket running, others the whole house. This often costs extra and does not work with every appliance.
How long does a battery last?
The consumer advice centre expects 10 to 15 years. It has to earn back its cost in that time.
Read on
In depth and with sources: from our guide.
-
Existing systems
Solar system over 20 years old: what to do when the feed-in tariff ends
What applies to your old solar system from year 21, what the follow-on payment brings, and when self-consumption, a battery or new panels pay off.
Request a battery check
With your system’s details and three photos we see what the job involves before anyone visits. It takes a few minutes and spares you an appointment that leads nowhere.