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Balcony solar calculator

Estimate the annual yield, self-consumption, saving and payback of a plug-in solar system – in three openly stated scenarios and optionally with a battery.

Your system

The sum of the module ratings. Up to 2,000 Wp is allowed for simplified registration.

At most 800 watts for simplified registration. The rating plate is decisive.

This value decides the result. It is not a location lookup: check it and adjust it for orientation, tilt and shading.

The share of the annual yield used directly in the household. Reported values vary widely: around 70 % is given by the consumer advice centre for a vertical module, the Federal Environment Agency works with about 70 %, and manufacturers state 30 to 40 % without a battery.

One-off cost after grant

A guide value for 800 Wp including installation by a specialist firm cannot be evidenced. The consumer advice centre gives around €300 to €500 for two modules with mounting.

Include payment for the surplus

Note: plug-in solar systems under § 8 (5a) EEG are assigned to free-of-charge offtake and in practice receive no payment. Payment requires regular registration with a bidirectional meter. The rate for systems up to 10 kW is 7.70 ct/kWh for commissioning between 1 Aug 2026 and 31 Dec 2026.

Include a battery

No reliable self-consumption figure for batteries is evidenced. The only value found is a manufacturer figure of 83 %. Treat the result as an assumption, not a measurement.

Everything you enter stays in your browser.

Three scenarios

How the calculator works

  • Annual yield (kWh) = module power (kWp) × specific yield (kWh/kWp). Self-consumption = annual yield × self-consumption share. Saving = self-consumption × electricity price + surplus × payment rate.
  • The specific yield is the decisive value and depends on location, orientation, tilt and shading. The calculator retrieves no weather or location data. The default is a dated guide value, not a value for your address.
  • The self-consumption share is the least certain figure in the calculation. Evidenced sources range from around 30 to 83 %. The calculator therefore shows three scenarios with openly stated assumptions.
  • No reliable self-consumption figure is evidenced for batteries. The calculator uses your own assumption and shows the result separately.
  • The simple payback is a static calculation. Financing, repairs, inverter replacement, cleaning and opportunity costs are not included. It therefore tends to overstate the economics.
  • The calculator does not output any CO₂ saving. No reliable dated emission assumption for the avoided electricity is available here, and the average grid factor overstates long-term savings.
Worked example

800 Wp, 900 kWh per kWp, 60 % self-consumption, €0.35/kWh, €700 investment, no running costs and no payment: annual yield 720 kWh, of which 432 kWh used yourself and 288 kWh surplus. The saving is €151.20 per year and the system is paid off after 4.6 years.

Legal framework

This reflects the position as of 27 Sep 2026. It is not legal advice.

  • Simplified registration requires inverter power of at most 800 VA and module power of at most 2,000 Wp (§ 8 (5a) EEG 2023). The rating plate and unit certificate are decisive, not pure software throttling.
  • Registration in the market master data register is mandatory, within one month of commissioning. Additional registration with the grid operator may not be demanded.
  • A Schuko plug is compliant up to 960 Wp module power and only for a device meeting DIN VDE V 0126-95. From 961 to 2,000 Wp an energy socket or fixed connection by a qualified electrician is required.
  • One plug-in solar system is allowed per billing-relevant meter; multiple sockets are not permitted. A battery must still be registered with the grid operator and connected by a qualified electrician.
  • Plug-in solar systems under § 8 (5a) are assigned to free-of-charge offtake. In practice no feed-in payment is therefore made.

Frequently asked questions

How reliable is the annual yield?

It depends on location, orientation, tilt and shading. The calculator retrieves no weather data but works with the specific yield you enter. The default is a Germany-wide guide value.

Why are there three scenarios?

Because the self-consumption share is the least certain figure and sources range from around 30 to 83 %. The three scenarios show how strongly the result depends on it and state their assumptions openly.

Do I get paid for the surplus?

In practice not for a plug-in solar system under § 8 (5a), because it is assigned to free-of-charge offtake. Payment requires regular registration with a bidirectional meter. The calculator only applies it if you enter it explicitly.

What does the payback time mean?

It says after how many years the annual saving reaches the investment. The calculation is static: financing, repairs, a later inverter replacement and opportunity costs are missing. It therefore tends to overstate the economics.

Where the defaults come from

The values are dated and are not updated automatically. Check them and replace them with your own figures.

  • Specific yield 1,000 kWh/kWp: PVGIS 5.2 of the European Commission, irradiation data 2005 to 2020, for 35° south without shading. Own queries on 27 Sep 2026 gave Munich 1,117, Berlin 1,056 and Hamburg 974 kWh/kWp. For vertical balcony mounting in Berlin only 765 kWh/kWp.
  • Self-consumption 60 %: own setting in the middle of the evidenced range. Consumer advice centre NRW and the Federal Environment Agency state around 70 %, a manufacturer figure without battery 30 to 40 % (low reliability). There is no single assured standard value.
  • Electricity price €0.35/kWh: a deliberately round example value. For orientation the BDEW electricity price analysis gives 37.0 ct/kWh for new-customer tariffs at 3,500 kWh (data as of 08/2026).
  • Investment €700: own setting above the €300 to €500 given by the consumer advice centre for two modules with mounting, because installation, connection and accessories come on top. No evidenced complete price including a specialist firm exists.
  • Payment rate 7.70 ct/kWh: Federal Network Agency for systems up to 10 kW commissioned between 1 Aug 2026 and 31 Dec 2026. For plug-in solar systems under § 8 (5a) no payment is made in practice.

Disclaimer

All information is provided without guarantee. The results of this calculator are a non-binding estimate and serve for guidance only. We accept no liability for incorrect, incomplete or wrongly transmitted input, or for the results calculated from it. Terms of Use