Germany has seen a huge surge in the installation of plug-in solar systems. The number of small systems registered increased more than sevenfold in the first quarter of 2023 compared to the same period last year, according to official figures.
“The market is huge,” plug-in solar advocate Christian Ofenheusle told DW. He runs the Berlin-based company EmpowerSource which promotes these relatively cheap mini systems. By 2030, he predicts there will be “12 million plug-in solar systems in Germany,” by the end of the decade.
Small solar systems are becoming more popular in China. In the megacity of Hangzhou, this is a common sight in large apartments, according to Hans-Josef Fell, president of the Energy Watch Group, a renewable think-tank in Berlin, and a former Green Party lawmaker.
In Italy, meanwhile, the largest electricity supplier, Enel, is also promoting this form of plug-and-play home energy generation.
There is “huge interest” in the technology in other European countries such as Poland, France, the Netherlands, the UK, Austria, Switzerland and Hungary, Ofenheusle said. Each of the states has also tried to cut red tape around the installation of such units.
Germany also plans to simplify the installation of the devices, with proponents saying they could complete the energy transition if enough people install them.
But how do plug-in solar modules work?
Residents can produce solar electricity themselves using one to three photovoltaic modules hung on balconies or walls, or placed on a terrace, roof or in the garden. Most importantly the devices do not require installation by a tradesman.
The direct current from the solar module is made into a small box where it is converted to grid-standard alternating current (AC) through an inverter. The unit can then be plugged into a standard wall outlet.
How much electricity does the solar porch generate?
Solar modules produce the most electricity in direct sunlight, so they are more productive in sunny regions and in spring and summer.
In parts of Africa, the Middle East, Australia, China, Latin America and the US, a 400-watt module can generate 800 kilowatt hours (kWh) of electricity per year. This is about half of less bright Germany and Central Europe.
But module placement is also important. It is best to align the modules facing south and at the best angle that gives power.
A 400-watt module installed on a south-facing front or balcony in Germany directly in the sunlight, generates an average of 260 kWh of electricity per year. A module facing east or west will still produce about 190 kWh per year.
Is the balcony module enough for the electricity needs of the house?
A plug-in solar module will only cover part of the energy needs of industrialized countries where per capita electricity consumption is relatively high. A four-person household in Germany consumes an average of about 4000 kWh per year, with one person using about 1500 kWh.
However, the electricity generated will help reduce electricity bills, say proponents.
In spring and summer, a 400-watt module facing south with the best angle of inclination can generate up to 320 watts on average, half as much if it is cloudy and about 50 watts only when it is very cloudy.
In the fall and winter, mini systems generate 160 watts when the sun is shining and only 20 watts when it is very cloudy.
So even in the dark of winter, there is enough power for an internet router, for example, which consumes about 10 watts. And a balcony module can almost always provide enough power for a small 80-watt refrigerator and a laptop of 40 to 100 watts.
But a plug-in module is not enough to run a powerful PC with two monitors of almost 900 watts, a 2000-watt washing machine or even a kettle, which uses between 600 and 2000 watts.
What does a plug-in solar system cost?
Plug-in solar systems with one to three panels cost anywhere between €400 and €1200 ($449 to $1,348) in German online stores.
With electricity prices currently around 30 to 50 cents per kWh, the panels will pay for themselves in six to nine years, said Thomas Seltmann of the Berlin-based German Solar Industry Association, which represents the interests of about 1000 solar businesses.
After that, the electricity generated by the module is free – and for at least another ten years. Today’s solar panels last an average of over 25 years, while inverters work for up to 15 years.
How safe are plug-in solar modules?
“Basically, plug-in solar units are very safe. No damage has been reported so far,” said Seltmann.
However, he recommends buying such systems from specialist dealers or online retailers who ensure that all the components are the same and provide installation instructions and advice. VDE, a German technical and scientific institution that tests and certifies electrical equipment, components and systems, makes similar recommendations, for the purchase of devices.
Such modules are also widely available, with 25 of the 27 European Union member states approving the systems – only Belgium and Hungary have yet to allow solar. Germany is also considering increasing the maximum limit of systems from 600 to 800 watts.
When installing the modules, residents must ensure that they are well secured and anchored to balconies or walls so that they can withstand wind and harsh weather conditions.
A DIY energy solution
Solar industry experts agree that plug-in solar units will only be able to cover a small portion of future electricity demand.
But the balcony modules also allow users to “enjoy” generating their own solar power, while promoting climate-friendly energy solutions, said Leo Ganz from the Bonn-based international company of market research, EUPD.
“These solar balcony installations are very important to mobilize people for energy transition,” he said.
This article was originally published in German.
