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How exactly do plug-in solar installations work?

It’s really easy to conserve electricity and contribute to climate action using your own balcony, patio or facade. But how exactly does a balcony-based power plant work? Who can benefit and what is to be considered?

Some 800,000 (in German only) plug-in solar installations are already generating low-cost, environmentally-friendly solar power on Germany’s balconies and patios. There are manifold benefits and the Solar Package I makes these even more easily accessible. No wonder that balcony-based PV installations are becoming more and more popular. Are you interested in learning more about these miniature solar installations?

^{This is how a plug-in solar installation works}

Plug-in solar installations consist of one or two solar modules and an inverter. The solar modules convert solar energy into direct current, which is then converted into alternating current by the inverter. This electricity is fed into the building’s grid and can be used to power devices such as refrigerators, TV sets, internet routers or washing machines. Any surplus electricity is fed into the public grid.

A plug-in solar installation is connected to the building’s grid via a connection cable once the solar modules and inverter have been connected to one another. The equipment usually comes with suitable fittings. Incidentally, there are many municipalities that offer co-funding for the purchase of a miniature PV installation. Even in the absence of such funding, it usually does not take long for the cost to have been recovered.

^{Who can benefit from a plug-in PV installation?}

The more solar power a household uses, the less electricity needs to be taken off the public grid. Whether or not a plug-in solar installation pays off depends on the cost of the installation, the direction in which the module is facing, and the electricity price. The best electricity yield is achieved when modules are facing south, fitted at an angle of 30 to 35 degrees, and if there is no shade. Apart from balconies, patios, gardens, fences, carports, rooftops and facades can also be used. Ideally, the installation will generate electricity for immediate consumption. For households whose peak consumption is in the mornings and evenings, it is often more efficient to have the modules fitted facing east or westwards. Consumers can easily calculate how much electricity and money they could save with a plug-in solar installation by using the plugsolar-package-in solar simulator of Berlin University of Applied Sciences (HTW) (in German only).

^{Balcony-based PV rendered even more simple by the Solar Package I}

The legal changes made under the Solar Package I (in German only) (see previous article) have made it even easier to generate your own electricity on the balcony and use it in your household.

Since October 2024, apartment owners and tenants have had the right to install a plug-in solar installation. While approval must still be sought, it can now only be refused in exceptional cases and with good reason. All that is required beyond this approval is the registration with the Bundesnetzagentur (in German only). Only very little data is required for this. The grid operator automatically ascertains whether the meter fitted in the household is approved for use with a plug-in solar installation. There is also a transitional period during which any type of meter can be used.

The grid operators are gradually exchanging traditional meters for digital ones, so as to be able to register power flows in both directions. The maximum feed-in quantity for inverters has been increased to 800 watts, allowing for an even greater range of household appliances to be powered by solar power generated by a plug-in solar installation. Furthermore, these installations can also be used in addition to an existing rooftop PV installation.

For a helpful checklist with points to consider when purchasing and operating a plug-in solar installation, complete with background information, consult the following publication by the Federal Ministry for Economic Affairs and Climate Action: Kurzinformation zu Steckersolargeräten (Summary information on plug-in solar installations) (in German only)