Retrofit a home batteryMatched to your system.

Many solar systems were built when storage was not yet a topic. Today feed-in payments are lower in many places, and your own electricity is worth more. That is why many owners retrofit a battery. This page is about retrofitting. If you are planning a new system, read battery storage.

Does a battery suit my system?

It comes down to four points:

• Inverter: Manufacturer, year of manufacture and output. Some units are already prepared for storage, others are not.
• Electrical distribution: Space is needed for protective devices and, for backup power, an additional distribution board.
• Meter and metering: The battery must measure the household consumption. A measuring device does this, from smart-me on request.
• Installation site: dry, frost-free, with room for ventilation.

At the free site visit, we check these points and tell you which option fits.

AC or DC coupling?

	AC coupling	DC coupling
Connection	to the house AC grid	to the DC side of the inverter
Inverter	battery brings its own, existing one stays	usually a hybrid inverter is needed
Retrofitting	simple, independent of the manufacturer	only if the inverter supports it
Conversion losses	slightly higher	slightly lower
Typical case	existing system, including older ones	new system or inverter replacement

In practice, AC coupling is the usual solution for a retrofit. It leaves your system unchanged. If the inverter is at the end of its life anyway, switching to a hybrid unit with DC storage can be the better choice. We calculate the two side by side for you.

Which inverters are suitable?

Almost any inverter can be extended with AC coupling, because the battery connects to the house grid and not to the inverter. With DC coupling, compatibility is narrower: the inverter must have a battery connection and support the battery you want. That depends on the manufacturer, model and year of manufacture.

So before the quote we check:

1. the rating plate and data sheet of the inverter
2. whether there is a communication interface for the battery
3. whether the output suits the battery
4. how old the unit is and how long it is likely to last

If the inverter is over 10 years old, we calculate both routes: battery on the existing unit or a new hybrid inverter. That shows you whether a replacement pays off now or only later.

Does a battery pay off on an existing system?

That depends on when you built your system and what tariff you receive. If you have a system with a low feed-in payment and use a lot of electricity in the evening, you gain the most. If you are at home during the day or already have high self-consumption, you gain less. We read your electricity bills and, if available, your smart meter data, and show you the difference. You will find a general introduction to size, service life and economics under battery storage.

Storage and new loads

After the battery, the next step often follows: an EV charger charges the car with solar power, a heat pump uses the surplus. We link everything through energy management, so that the battery, car and heating do not work against each other.

Retrofitting backup power

A retrofitted battery can also keep supplying during a power cut. For this you need a unit capable of backup power and a changeover in the electrical distribution. This is extra work, which we show separately. Whether you protect individual circuits or the whole house is up to you.

What does retrofitting cost?

The costs depend on capacity, coupling, backup power and the work on the distribution board. As a guide value, a battery of 8 to 12 kWh for a single-family home, installed, costs around CHF 8,000 to 15,000. We give the exact figure only after the site visit, in the binding quote within 72 hours. There you will also see how much self-consumption rises and when the battery pays for itself.

Subsidies

The federal government does not subsidise batteries directly. But some cantons, communes and energy suppliers pay contributions, and the conditions differ by location. We clarify what is possible for your address and register you. On request, we pre-finance the subsidies we handle. In most cantons, the costs can also be deducted from tax.

How the retrofit runs

1. Enquiry: Online or by phone.
2. Site visit: We check the inverter, distribution board and installation site. Free of charge.
3. Quote within 72 hours: binding, with AC and DC options if both are possible.
4. Registration: We register the battery with the grid operator.
5. Installation: Our own installers, usually one to two days.
6. Commissioning: We set up the app and explain the display to you.

If you would like to enlarge the system at the same time, read extending your solar system.

Battery retrofits in your region

We are based in Zumikon ZH and Lachen SZ and retrofit across German-speaking Switzerland. Even if your system was not built by us, we are glad to check it.