Heat pump with solar system: is the combination worth it?Heating with your own power.

A solar system lowers the running costs of a heat pump, but it does not replace grid power completely. In the example below, the system covers about 30% of the heat pump’s electricity. The rest comes mainly from the grid in winter. If you know this, you plan the combination realistically.

Why the two fit together

A heat pump turns 1 kWh of electricity into several kWh of heat. You do not have to buy that electricity from the grid. Every kilowatt-hour from your own roof replaces one you would otherwise pay for at the grid tariff. In the household tariff, the median in 2026 is 27.7 ct./kWh excluding VAT according to ElCom (Federal Electricity Commission), and 26.6 ct. for 2027.

There is another point: a heat pump can be controlled. It can heat the hot water when the sun is shining. Electricity that would otherwise flow into the grid becomes heat in your own tank.

The winter problem

A heat pump needs the most electricity in December and January. That is when a solar system delivers the least. Even a large system cannot change this. A home battery helps through the night, not through weeks of fog.

Spring and autumn look different. On clear days the heat pump runs on solar power, and in summer only hot water is needed. The combination covers the shoulder seasons well and winter only in part.

Worked example

The assumptions match the examples on our website. This is not a quote.

• Heat demand of the house: 20,000 kWh per year for heating and hot water.
• Air-to-water heat pump with a seasonal performance factor (SPF, JAZ) of 3.5: 20,000 / 3.5 = about 5,700 kWh of electricity per year.
• Solar system with 10 kWp and 1,000 kWh per kWp: about 10,000 kWh yield per year.
• Electricity price: 27.7 ct. per kWh excluding VAT.

Over the year the system produces more electricity than the heat pump needs. But the yield comes in summer and the demand in winter. If the system covers 30% of the heat pump’s electricity, that is about 1,700 kWh. At 27.7 ct. you save about CHF 470 per year. With better control and a battery, the share rises.

The values depend on roof, orientation, house and behaviour. We calculate your figures during the site visit.

How big should the system be?

A system for the household alone is usually not enough for a heat pump. More modules bring more electricity in the shoulder seasons. The roof limits the size, though, and the summer surplus flows into the grid, where it is paid only at the feed-in tariff.

This is how we proceed:

1. We estimate the heat pump’s electricity demand from your previous oil or gas consumption.
2. We add the household and, if planned, the car.
3. We check how much roof area is usable.
4. We size the system so that every additional module still pays off.

Guide prices for the solar system before subsidies: 5 kWp about CHF 14,000 to 19,000, 10 kWp about CHF 24,000 to 30,000, 15 kWp about CHF 33,000 to 42,000. These are ranges, and our quote is binding. More in the guide Solar system cost.

With or without a home battery?

The hot water tank is the cheapest storage in the house. It takes up solar heat at midday and releases it through the day. A home battery comes in on top if you want to use more of your own power in the evening and at night. As a guide, 8 to 12 kWh cost between CHF 8,000 and 15,000. In a household alone, self-consumption is 30 to 35% without storage and 60 to 70% with storage.

With a heat pump the calculation shifts. Self-consumption rises even without a battery, because the heat pump runs during the day. The battery then adds less than in a household alone. We therefore check system and controls first, and then whether a battery still belongs in the plan.

Existing solar system: does it fit?

If you already have a system, we check three things:

• Do the inverter and meter suit the connection of the heat pump?
• Is the yield enough, or is it worth extending the solar system?
• Can a home battery be retrofitted?

Often a new control unit is enough to make the heat pump run at midday. That costs less than new modules.

Subsidies for both

The two parts are subsidised separately. For the solar system, Pronovo pays the one-off payment (Einmalvergütung). Since 1 April 2025 there is no base amount any more. Add-on systems under 30 kWp receive CHF 360 per kWp, integrated ones CHF 400 per kWp (EnFV Annex 2.1). For the heat pump the cantons are responsible, usually through their buildings programme. The amounts differ from canton to canton. What applies to you is on our canton pages, for example for Zurich or Schwyz. The basics of heating subsidies are in the guide Heat pump subsidies.

We submit both applications for you. The subsidies can be pre-financed on request.

What we consider in planning and control

• Joint electrical planning: We build the meter cabinet, supply line and controls once, even if the system follows later.
• Hot water at midday: We set the heat pump so that the tank is charged when the sun is out. We also schedule the hygiene heating in these hours.
• EV charger: With an EV charger you use the surplus as well.
• Apartment building: With a ZEV (self-consumption community), several parties share the solar power for heat pump and household.

A heat pump also pays off without a solar system if the old heating has to be replaced. The system can be added later if the preparation is right. See also the guide Heat pump cost.

Common mistakes with the combination

From our planning work we know a few points that cause trouble later:

• System sized too small: If you size the solar system only for household consumption, it covers almost none of the heating electricity.
• Wrong expectations in winter: If you believe the system will supply the heat pump in January, the electricity meter will surprise you. Plan with grid power in winter.
• Controls forgotten: Without a connection, the heat pump runs on a schedule and not by the sun. The controls cost little and bring a lot.
• Electrical installation underestimated: Old meter cabinets and thin supply lines often have to be adapted. That belongs in the first quote and not in a supplement.

If you clarify these four points early, you get a solution that works in daily life as planned.

We calculate it for your house

How much of the heating electricity your roof can supply, we only know on site. We come for a free site visit, check heating, roof and electrical installation and give you a binding quote within 72 hours for heat pump and solar system from a single source, with subsidies and running costs.