How many kilowatts peak (kWp) does your house need? The rules of thumb contradict each other: size by consumption, by roof area, or simply as large as possible. kWp is the panels’ peak output under test conditions; it tells you how big a system is, not how much power it produces. Here is how much power one kWp produces around Munich, how to find the right size and which limits matter.
In short
- Plan for tomorrow’s consumption: a heat pump or an electric car changes your power needs more than anything else.
- The roof sets the limit: each kWp needs about five to seven square metres.
- Bigger usually costs less per kWp: scaffolding, inverter and registration are needed anyway.
- Up to 30 kWp, tax stays simple: for a family home that is rarely a limit.
What one kWp produces here
How much power a system produces depends on orientation, tilt and shade. The European Commission’s PVGIS yield calculator gives these yields per kWp and year for a location in Munich, with a 35-degree roof pitch and 14 per cent system losses:
East- and west-facing roofs produce less but spread the power over the day: in the morning and evening, when many households need it. The Verbraucherzentrale, Germany’s consumer advice centre, considers such systems often worthwhile too. You can try PVGIS for your own roof; it does not know about shade from trees or neighbouring houses, though.
Three ways to the right size
- 1. Start from consumption What you use today and tomorrow.
- 2. Start from the roof How much area your roof has.
- 3. As large as the roof allows Using the whole roof.
1. Start from consumption
Look at your electricity bill and ask what will be added in the coming years. A solar system lasts two decades and more; people often buy a heat pump or an electric car later. The calculator further down shows what size your consumption needs and what fits on your roof.
2. Start from the roof
According to the Verbraucherzentrale, about 1 kWp needs about five to seven square metres. Windows, chimneys, dormers and the required distance from the edges take up space.
What size fits?
Your use today, what comes next, and your roof. The starting values are an example.
Together 10,000 kWh a year. With 30 per cent more, the system should make 13,000 kWh.
Tight: it depends on the exact usable area.
Our rule of thumb: the system makes about 30 per cent more power a year than the house uses. Output per kWp in Munich from PVGIS, east-west as the average of both sides; 5 to 7 square metres per kWp according to the Verbraucherzentrale. Source: PVGIS · Verbraucherzentrale (consumer advice centre)
Grant from your municipality? Open the subsidy finder →3. As large as the roof allows
Small systems cost more per kWp, because fixed costs such as scaffolding and the feed-in equipment always apply. The Verbraucherzentrale therefore considers larger systems usually more worthwhile, limited by roof area and budget. A few extra panels cost relatively little; adding them later costs a lot: new scaffolding, a new registration, often a second inverter.
From our work: Our rule of thumb has always been: the system produces about 30 per cent more power a year than the house uses. With a battery, that gives a good level of self-sufficiency. Bigger was almost always better, because extra panels cost relatively little. Even if the fixed tariff for new systems goes, I would still build rather large: new ways to use the power are coming, such as sharing it with neighbours. Panels on a steep north-facing roof make less sense when a heat pump needs most of the power in winter.
What is changing
The fixed feed-in tariff for new systems is set to end from 1 January 2027. New rooftop systems under 100 kW would also be allowed to feed at most half of their output into the grid. That is what the draft EEG 2027 (Renewable Energy Sources Act, Bundestag printed paper 21/7867) says; it has not been passed yet. More in our article on the EEG 2027.
For sizing, this means the power you use yourself matters even more. A large system then pays off mainly with a battery, a heat pump or an electric car. There is also a new option. Since 1 June 2026, grid operators must let you share power from your system with others, such as neighbours in the same grid area (section 42c of the Energy Industry Act, EnWG). From 1 June 2028 this must also work with the neighbouring grid area. Everyone involved needs a meter that measures every quarter of an hour. How well this works in practice remains to be seen.
Limits that matter
- Income tax: income from solar systems on, at or in buildings is exempt from income tax, up to 30 kWp per home or business unit and at most 100 kWp per person in total (section 3 no. 72 of the Income Tax Act, EStG).
- VAT: panels, batteries and installation for systems on or near residential buildings carry 0 per cent VAT. For systems up to 30 kW according to the market master data register (Marktstammdatenregister), this condition counts as met (section 12(3) of the VAT Act, UStG).
Next step
Tell us your annual consumption, which way your roof faces and whether a heat pump or an electric car is planned. Through our enquiry form we work out which size suits your house, and we look at your roof and meter cabinet on site. What fits on a typical house in Munich is on our page solar in Munich, worked out for every city district. We advise in English.