Battery storage for your solar systemKeep your own power.

A battery storage system (also called a home battery or solar battery) stores the solar power you do not use during the day. In the evening and at night, you use it yourself instead of buying electricity. The battery belongs with the solar system: it charges from your rooftop power and releases it again when needed.

If you are building new and plan the system and battery together, you save effort. If you already have a system, you will find the solution under retrofitting a battery.

Why a battery with a solar system?

A solar system produces the most when you are at home the least: at midday and in summer. Without a battery, a household uses about 30 to 35 per cent of its own solar power itself. The rest flows into the grid.

With a suitably chosen battery, self-consumption often rises to 60 to 70 per cent. These values are guide figures. How high they are for you depends on the size of the system, the size of the battery and your daily routine.

Self-consumption pays off because power you use yourself is worth more than power you feed in. You pay the full tariff for grid electricity, but you only receive the feed-in tariff for power fed into the grid.

How large should the battery be?

Too small helps little, and too large stays empty in winter and costs more than necessary. This is how we proceed:

1. We read your annual consumption and daily profile from your electricity bills and, if available, from smart meter data.
2. We take your heat pump, electric car and home office into account.
3. We calculate several battery sizes and compare self-consumption and price.

For single-family homes, 8 to 15 kWh of usable capacity is typical. A four-person household without a heat pump or electric car uses about 4,500 kWh a year, and a third of that falls in the evening and at night. With a heat pump and electric car, demand rises significantly, and so does the sensible battery size.

Backup power: electricity even during a grid failure

A system without a backup power function switches off during a grid failure, even with a battery. With a backup-capable battery, part of the house keeps running. There are two levels of installation:

Option	What stays powered	Suitability
Backup power for individual circuits	Fridge, lighting, internet, heating controls	Standard, less effort
Backup power for the whole house	All loads, limited by the output	More work on the distribution board and inverter

Backup power has to be planned from the start. It needs a suitable inverter and an adapted electrical distribution. In backup mode, a heat pump or wallbox only runs if the battery output is sufficient.

What types of battery are there?

• DC-coupled: The battery is connected to the direct-current side of the hybrid inverter. This is the usual solution for new systems, because there are fewer conversion losses.
• AC-coupled: The battery has its own inverter and is connected to the house’s alternating-current network. This is the common choice for existing systems.
• Technology: Lithium iron phosphate (LFP) cells are mostly used. They are considered durable and thermally stable.

More on the coupling types and on retrofitting is under retrofitting a battery.

Battery, EV charger and heat pump together

A battery shows its value when many loads work together. We connect the system to an EV charger and a heat pump and control them through an energy management system. The car then charges first with surplus power from the roof, and the heat pump runs when the sun is shining. As a smart-me Partner 2025, we also integrate the metering for this.

What does a battery cost?

The price depends on capacity, output, backup power function and installation effort. As a rough guide value, a battery of 8 to 12 kWh for a single-family home costs about CHF 8,000 to 15,000 including installation. Because systems and houses vary so much, we do not quote a flat rate. After the site visit, you receive a binding quote within 72 hours, with and without a battery, so that you can see the difference.

A rule of thumb for when a battery is more likely to pay off:

• The feed-in tariff of your grid operator is low.
• You use a lot of electricity in the evening and at night.
• You have an electric car or a heat pump.
• You want to keep having power during a grid failure.

If you already use a lot of electricity during the day, a battery is less worthwhile. We will tell you that too.

How long does a battery last?

The service life depends on the number of charge cycles. One cycle is one full charge and discharge. Modern LFP batteries are designed for several thousand cycles. At one cycle a day, that often means 10 to 15 years or more. These figures are guide values from the manufacturers. What is binding is the warranty stated in the quote.

Capacity decreases slowly over the years. Manufacturers usually guarantee a remaining capacity after a certain time or amount of energy. We tell you the conditions of the unit we propose before you sign.

Heat and cold put stress on cells. That is why we install the battery inside the house, not outdoors, and pay attention to ventilation and clearances.

Economics: is a battery worthwhile?

The honest answer is: it depends. A battery costs money and brings more self-consumption in return. Whether that pays off is determined by three figures:

• Your electricity price: the higher the tariff for grid electricity, the more each kilowatt-hour from the battery saves.
• The feed-in tariff: the lower it is, the less you lose by storing power instead of feeding it in.
• Your evening consumption: if you use a lot in the evening and at night, you empty the battery every day and use it fully.

A battery also has a benefit that the calculation only partly captures: independence from the grid and backup power. Whether that is worth the extra price to you is your decision. We show both options in the quote so that the difference is visible, and we will advise against a battery if it brings you hardly anything.

Where is the battery installed?

The battery is usually installed in the utility room, the cellar or the garage, close to the inverter and the electrical distribution. It needs a dry, frost-free room with enough space for ventilation, and the floor must carry the weight. Depending on the model, there are wall-mounted or floor-standing units. During the site visit, we measure the space and mark the cable route.

The battery in winter: what to expect

In winter, the system produces less power, and the battery is full less often. On sunny winter days and in spring and autumn, it still helps to bridge the evening. It is most useful from March to October. A battery does not make you independent of the grid in winter. We tell you that clearly before you buy.

Which brand?

We choose the battery to match the inverter, power demand and backup power requirements. What matters is a warranty you understand, a good connection to the energy metering and a manufacturer that will still provide support in ten years. Which units we propose is stated in the quote, with warranty and datasheet.

Battery and electricity price

If you have a dynamic electricity tariff, you can also use the battery to charge from the grid in cheap hours. This is an additional function that we discuss with you if your grid operator offers such a tariff. The main purpose remains self-consumption of your solar power.

Subsidies

• Federal government: The Pronovo one-off payment (Einmalvergütung, EIV) applies to the solar system. The battery itself is not directly subsidised by the federal government.
• Canton and commune: Some cantons, communes and energy suppliers pay contributions towards batteries, often in connection with a solar system or heat pump. The conditions differ by location. We check what is possible for your address.
• Taxes: In most cantons, you can deduct the investment in an existing building from your taxable income.

On request, we pre-finance the subsidy we handle for you.

How your project works

1. Enquiry: Online in a minute or by phone.
2. Site visit: We check the roof, electrical installation, installation location and consumption. Free of charge.
3. Quote in 72 hours: binding, with battery size, self-consumption and economics.
4. Notification and grid operator: We handle the registration of the system and the battery.
5. Installation: Our own installers fit the system, battery and electrical connection.
6. Commissioning: We explain the app, where you see charge level, yield and consumption.

Planning, notification, installation and commissioning come from one provider.

Battery storage in your region

Our locations are in Zumikon ZH and Lachen SZ. We build throughout German-speaking Switzerland, most often in the Cantons of Zurich, St. Gallen, Schwyz and Aargau. You can read more about the system itself under solar system.