Guide · Solar power and electric car
Charging an electric car with solar power: what does your own system add?
Anyone who wants to charge an electric car with power from their own roof first asks how much of it stays in the house and what that is worth. We calculated it for a roof system of 6 kWp in Zurich, tilted 30 degrees, facing south. It delivers 6’870 kilowatt-hours a year. In a house without an electric car (4’500 kilowatt-hours a year) you use 1’739 of that yourself, in a house with an electric car (7’500 kilowatt-hours) 2’598. The car thus adds 859 kilowatt-hours of self-consumption to the system.
What the car changes about the roof system
In this comparison the car needs an additional 3’000 kilowatt-hours a year. 859 of them, or 29 per cent, come from your own roof, the rest from the grid. The self-consumed share of the system rises from 25,3 to 37,8 per cent. A self-consumed kilowatt-hour replaces grid power at 25,79 centimes, a fed-in one earns the minimum remuneration of 6,00 centimes. The gap of 19,79 centimes comes to about CHF 170 a year at 859 kilowatt-hours. Both tariffs are net; on the electricity bill, value added tax is added to the power you draw.
These figures apply to a car that charges like the rest of the household. The daily curve is synthetic, with a morning and an evening peak; we have no real quarter-hour values. If you charge deliberately at midday, the car gets more out of the system, if it charges at night, less. How much more and how much less we have not calculated.
Plug-in solar: the panel is not enough for a car
The LANDI panel of 400 Wp delivers 460 kilowatt-hours a year in the simulation (Zurich, mounted at 35 degrees) and uses all of it itself, with and without a car. At 18 kilowatt-hours per 100 kilometres, 460 kilowatt-hours are good for about 2’600 kilometres. On the survey day the panel cost CHF 249 and could not be ordered. It lowers the household’s power draw, but changes little about charging the car.
What a roof package costs
Helion offers two packages together with IKEA: 9,1 kWp for CHF 24’999 and 10,92 kWp with a 7 kWh battery for CHF 35’999, both after deducting the subsidy. The CHF 170 a year is the car’s contribution at 6 kWp. The contribution grows with the system: at 2 kWp it is 493 kilowatt-hours more self-consumption, at 10 kWp 1’021. When a whole system pays for itself, this article does not show.
What this means for you
- Your own roof, a car is coming. At 6 kWp that is 859 kilowatt-hours more self-consumption, about CHF 170 a year net.
- No roof of your own. As a tenant or condominium owner it depends on the building community, see Right to charge and, in the tab Charging, the section on solar power from the building.
- A heat pump in the house. Then the calculation does not apply: ElCom puts this house at 13’000 kilowatt-hours a year, more than anything we simulated.
What we do not know
- When your car charges. Self-consumption depends on it most, and we do not know it.
- Other locations and orientations. The calculation is Zurich, south. Ticino, the Valais and an east-west system are not measured.
- The market. Two providers are a sample, and a price is a snapshot.
How power from the car battery comes back into the house is in the article Bidirectional charging, charging without your own wallbox in EV without a wallbox and the running costs as a whole on Total cost.
Sources: yield and self-consumption from our own simulation with PVGIS of the EU Joint Research Centre, location Zurich, as of 14 September 2026: pvanlagen.json ↗. Household tariff: ElCom, profiles H4 and H5, tariff year 2026, net. Minimum remuneration: Article 12 paragraph 1bis of the Energy Ordinance. Device prices from LANDI and Helion, read on 14 September (LANDI) and 11 September 2026 (Helion): pvgeraete.json ↗.
Transparency: the calculation covers a roof system at 4’500 and at 7’500 kilowatt-hours of annual consumption, the two ElCom levels H4 and H5. The difference of 3’000 kilowatt-hours is the car’s consumption; the value of 18 kilowatt-hours per 100 kilometres comes from the classification of households on our site. The load profile is an assumption. The device prices are snapshots from 11.09.2026 and 14.09.2026.
