With plug-in solar devices, you can also generate your own solar power as a tenant or apartment owner. We will tell you what you should pay attention to.

Table of contents:

1. What is a plug-in solar device and how does it work?
2. What is the difference to a photovoltaic system?
3. Is a plug-in solar device suitable for my apartment?
4. Are plug-in solar devices safe?
5. How big are plug-in solar devices and which size suits me?
6. What is the benefit of a plug-in solar device? Is it worth it for me?
7. Is there a subsidy for plug-in solar devices?
8. Where do I have to register a plug-in solar device?
9. Do I need a new meter?
10. What should I consider when buying?
11. How do I know if it works and how much it does?
Checklist: Step by step to the plug-in solar device

The most important things in brief:

  • You can also generate solar power yourself on the balcony or terrace and consume it in the household.
  • Plug-in solar devices produce electricity for own use, but are not intended for mains power supply.
  • The balcony modular systems are safe and are also financially worthwhile in the long term.
  • Some rules and requirements are still unnecessarily complicated at the moment, but you should not be deterred by this.

1. What is a plug-in solar device and how does it work?

Do you have a balcony or terrace? Then you can gain your own solar power there and become an active part of the energy transition: With a plug-in solar device. These small photovoltaic systems are often also called mini solar systems, plug & play solar systems or balcony modules, because they can be mounted on the balcony parapet, for example. However, this is not a “plant” in the technical sense, but rather an electricity-generating household appliance.

What can a plug-in solar device do?

The solar module generates electric current from sunlight, which an inverter converts into “household electricity”. This is connected directly to an existing circuit in the apartment. In the simplest case, plug a plug into an existing socket.

The electricity from the plug-in solar device flows, for example, into the socket on the balcony and from there to the TV, refrigerator and washing machine, which are plugged into other sockets in the apartment. Then the electricity meter counts more slowly, less electricity is obtained from the public grid. If the electricity from the balcony is not sufficient for the operation of the household appliances, electricity simply flows from the supplier from the grid.
Without a grid connection, the solar devices do not produce electricity. When camping or in the allotment garden, you can instead use so-called “island systems” with a battery and another type of inverter.
Plug-in solar devices usually consist of 1 or 2 standard solar modules and an inverter. Depending on the equipment, other components are added.

Solar power modules

A plug-in solar device consists of one or two solar modules. A module has approx. 300 watts rated power, is about 1 x 1.70 meters in size and weighs up to 20 kg. Some systems also consist of several smaller modules.


It is integrated into the solar module or attached separately, for example to the module frame.

Connection cable

From the inverter, a cable leads to a suitable outdoor socket.

Function control

With the help of a current meter – with or without an Internet connection – you can check how much electricity is produced.

Secure mounting

Solar modules must be fastened with suitable mounting materials so that they can safely withstand wind and weather. Clarify in advance whether the selected solar modules may be mounted at the planned location. Not all modules are suitable for every balcony, and the consent of landlord:in or condominium association is necessary.

Simply click on the marked dots in our graphic – then you will receive more information:

Solar modules

The standard modules are about 1 meter by 1.7 meters in size, weigh about 20 kilograms and deliver a rated power of 280 to 350 watts. In addition, solar modules without a glass front or smaller-format solar modules are also offered, which are particularly suitable for easier installation, for example on the balcony.


2. The inverter contains the electronics that convert the direct current generated by the solar module from sunlight into alternating current in such a way that the generated electricity flows directly into the power grid of the house and can be used by the existing household appliances. This module inverter meets all technical and safety requirements that even larger devices must meet. It is usually suitable for outdoor use.

Connection to the power grid

The connection to the power grid is made via a cable with a plug connection. A fixed connection is usually not provided so that the plug-in solar unit can be plugged in or out at any time and you can use it elsewhere without having to commission an electrical installation operation. You should be able to find out which connector is intended for the connection in the manufacturer’s company’s specifications. Basically, there are two options, the special plug type “Wieland” or the Schuko plugs common in households. Incidentally, it does not matter to which of the three phases of the power grid a plug-in solar device is connected, the power is also used by devices on the other two phases.

Solar panel attachment

Special care should be taken when mounting the solar module. The installation location and the fastening material must be suitable for this. You should also find information on this in the manufacturer’s company information (operating instructions). Most companies also sell ready-made assembly sets. Above all, it is important here that the solar module cannot be damaged by wind or fall down by its own weight.


To see if the plug-in solar device works as it should and how much energy it supplies, a suitable measuring device is recommended. For some inverters, there are additional devices that take over this function. Otherwise, you can also use socket measuring devices or measuring sensors that can be called up via WLAN or Bluetooth.

Battery storage

The solar power is not stored in the plug-in solar device, but fed into the home power grid and consumed directly. Individual manufacturers always have small battery storage systems in their program. So far, however, there are no products that are financially attractive. That’s why we advise against it.

2. What is the difference to a photovoltaic system?

In contrast to photovoltaic systems, the much smaller plug-in solar devices are intended for private individuals to install, connect and use them directly. You may also register with the network operator and the market master data register yourself. The mini solar systems can also be easily removed and continued to operate elsewhere, for example during a move. They have a power of up to 600 watts (inverter power).
Photovoltaic systems on private homes, on the other hand, have an output of between 3 and 20 kilowatts (kWp). They consist of several components, the installation and maintenance of which must be carried out by a specialist company, which also handles the necessary technical inquiries and registrations with the local network operator. The PV system is permanently installed for permanent operation and can only be removed with considerable effort and moved to another building.

3. Is a plug-in solar device suitable for my apartment?

Basically, a plug-in solar device is suitable for apartments with
a balcony or
a terrace or
a roof area above the apartment or in front of the window, a garage roof or
an outdoor wall surface oriented towards the sun.
A plug-in solar device is significantly cheaper than a photovoltaic system and can therefore also be financed for low-income earners.
You can also put a plug-in solar device on the terrace or in the garden. When moving, you can simply take the device with you.

The following applies to rental and condominiums: If you want to install the solar module on the balcony parapet or the house wall, landlord or condominium usually have to agree. Since the Residential Property Act (WEG) was amended in 2020, no unanimity is necessary for this, but only a majority permit.

4. Are plug-in solar devices safe?

The devices are basically very safe. In the meantime, more than 190,000 such systems are already in operation in Germany (as of the end of 2021). So far, not a single case of property damage or injured persons has become known. This is because the technology used is mature and the same components are used in professionally installed photovoltaic systems. Only standard-manufactured and tested components may be used.
Plug-in solar devices are safe if the module inverters used meet the requirements that are also placed on inverters for normal photovoltaic systems. The installation standard also provides that an electrician checks the suitability of the circuit for feeding solar power.
Above all, you should only connect a single plug solar device (inverter) to a socket or circuit at a time. The coupling of several devices via a multiple socket would be dangerous.
A product standard according to which the devices can be tested and certified is currently being developed. The DIN Consumer Council and the Consumer Center are also involved in this, a publication is expected in 2022. Until this product standard is published, you can, for example, orient yourself to the safety standard published by the German Society for Solar Energy (DGS) when purchasing.
You should also follow the instructions for connection and use provided by manufacturers with the device. You should also learn from them how to securely attach the solar module and inverter to the intended mounting location.

5. How big are plug-in solar devices and which size suits me?

We mean plug-in solar devices solar modules with up to 600 watts of connection power with an inverter, which are connected to a circuit in the household.
These can be 1 to 2 standard solar modules (in the format of about 1 x 1.70 meters) of current design, which typically have about 350 to 380 watts of nominal power each. In the next few years, the electrical power of the standard modules will rise to about 400 watts through further improvements.

The 600 watts mentioned refer to the connection power of the inverter on the power grid side (AC). Two modules with 340 watts each (i.e. together 680 watts of module power) may also be operated, provided that the connection power of the inverter does not exceed 600 watts.

Alternatively, smaller, lighter solar modules are also available, which can be more easily attached to balcony parapets, for example. These have 50 to 150 watts of power, and 2 to 4 of them can be connected to a module inverter.
Tip: If you use as much solar power as possible yourself and want to avoid a grid feed-in, we recommend a power of 200 to 400 watts, usually this is a standard solar module with 350-380 watts. If you want to generate more solar power, two standard solar modules are also suitable for you.
In principle, plug PV systems with higher power could also be set up. At the latest then, however, an electrician is necessary to check all the technical requirements of the power connection and register the device with the grid operator. From our point of view, it is then more of a photovoltaic system than an electricity-generating household appliance, as is the case with plug-solar.
However, the higher installation effort for a photovoltaic system is usually only financially worthwhile with significantly larger system outputs of more than 3 kilowatts.

6. What is the benefit of a plug-in solar device? Is it worth it for me?

With a plug-in solar device, you make your own personal contribution to the energy transition. The mini solar systems usually produce enough electricity to cover a significant part of the base load and midday peak of a household on sunny days.
A standard solar module with 380 watts of power, which was mounted on a south-facing balcony without shading, provides about 280 kilowatt hours of electricity per year. This reduces your electricity purchase by about the same amount if you can consume the electricity directly in the household.
This amount of electricity corresponds approximately to the annual consumption of a refrigerator and a washing machine in a household with 2 people. With an average electricity price of 33 cents, this brings an annual saving of around 66 euros.
A plug-in solar device with standard module usually costs between 350 and 600 euros. Since demand is currently very high and the delivery of components is delayed, prices are currently partly significantly higher. In return, however, electricity costs in households have also risen significantly for several months.

South roof

An annual yield of about 260 kWh is realistic.

South-facing balcony

The annual yield should reach about 200 kWh if the module is mounted vertically to the balcony parapet. It rises to up to 250 kWh, depending on the angle at which the module is aligned.


The annual yield can range from 130 to 200 kWh. It depends heavily on how much objects are in the immediate vicinity, e.g. Houses, trees or bushes, cast shadows on the module.

East or west balcony

The annual yield brings about 150 kWh. An inclination of the module can increase the yield.

North balcony

The yield here is well below 100 kWh. Therefore, a module is hardly worthwhile at this point.

The yield of the device and thus its profitability depend on various factors. This includes the acquisition costs, the orientation of the module and as little shading as possible. Particularly useful is the vertical mounting on the outside of a balcony parapet, which is designed to be shade-free to the southwest to the southeast. The vertical arrangement reduces the unusable production peaks in summer and increases the usable yields in the winter half-year.
For a location with average sunshine duration in Germany, you can estimate the profitability of a plug-in solar device with the plug-solar simulator of HTW Berlin.

However, you not only reduce your electricity bill, but also do something good for the environment: The mini solar system saves about 2.5 tons of CO2 emissions in 20 years.
Unsuitable mounting locations are:
behind the balcony parapet in the balcony niche,
on the wall under the balcony of the above floor,
Places with shading, for example through trees, lantern poles or neighboring buildings.
Permanent, even partial shading or contamination of the modules can lead to yield reductions, which have a significantly greater impact than with a photovoltaic system. Therefore, you should check your module regularly and remove dirt.
We have also prepared the most important information on this topic for you as a podcast. In the episode “Solar power from the balcony” Marie Hartmann talks to Thomas Seltmann, photovoltaic expert at the NRW Consumer Centre, among others. Listen to it!

7. Is there a subsidy for plug-in solar devices?

More and more municipalities, individual federal states and regional associations are promoting plug-in solar devices through subsidies. In addition, network operators and electricity suppliers are increasingly supporting this application by simplifying registration and not hindering use or even actively promoting such systems. But be careful: Often requirements are also specified in the conveyor conditions, e.g. the use of a special feed-in socket or the verification of the electrical installation by an electrician. In order not to get any problems with funding, these points must then also be implemented.
For plug-in solar devices, the EEG feed-in tariff is usually also dispensed with. For example, if a plug-in solar device generates 500 kilowatt hours of electricity annually and 150 kilowatt hours of it flow into the grid, this would mean a feed-in tariff of around 12 euros per year. This would then be offset by a regular reading and billing effort.

8. Where do I have to register a plug-in solar device?

In its EU Regulation 2016/631, the European Union classified small producers under 800 watts as “not significant” because they are “not systemically important”.

Nevertheless, the German network operators want all generation plants, regardless of their performance, to be reported to them. They have written this requirement in the corresponding provision (application rule VDE-AR-N 4105). A simplified form is provided for generators up to 600 watts of AC power, including plug-in solar devices according to our definition. After all, an electrician does not necessarily have to fill out this form, you can also do this yourself if you use a plug-in solar device.
Many network operators provide the simplified forms on their website, some send them on request. Some even offer a particularly convenient online registration. You must attach a data sheet of the inverter used to the registration, which shows that the device meets the requirements for the mains connection (declaration of conformity).
Assistance with registration is available from some manufacturer companies of balcony modules.
Although it is controversial whether plug-in solar devices are “systems” at all, at least if these systems are not firmly connected, but are connected to the circuit via a plug like household appliances, the Federal Network Agency also requires registration in the market master data register.
Tip: If you register a plug-in solar device with the network operator or the Federal Network Agency, you can assume that the other institution will also know about this registration. It is then advisable to carry out both registrations and enter the same data.
For consumers, the registrations have no advantages, they only create bureaucratic effort. Since a plug-in solar device is also formally a grid-coupled PV system, registrations are required. Without registration in the market master data register, a fine may threaten.
Note: If you already have a PV system on the roof whose electricity is partially consumed in the household, the plug-in solar device is only a simple extension of the existing and already registered system. The necessary meter is then already available. You must report this extension to both the network operator and the market master data register.

9. Do I need a new meter?

Even if plug-in solar devices are intended for self-consumption and not for grid feed-in, electricity can flow into the grid. Technically, this is not a problem, and it is also allowed if you use inverters that comply with the standard.
Due to the plug-in solar device, conventional electricity meters with mechanical turntables (“Ferraris counters”) run backwards, because these meters are not equipped with a return lock. Therefore, the network operator, as the basic measuring point operator, converts the conventional meter into a modern electronic meter, which is also called a modern measuring device (mME).
These meters are available in two versions: Setup meters continue to measure only the power supply and do not count backwards when electricity flows into the grid. The (low) excess feed is not measured in this meter variant.
The second option is a two-way counter. Technically, these are the same meters, but they are programmed in such a way that they record and display both counting directions – the power supply from the grid and the return to the grid – separately. Such meters are also used in photovoltaic systems with surplus feed.
Over the next few years, the legislator provides that all electricity meters in Germany will be replaced by such modern measuring devices as part of the so-called smart meter rollout.
If your network operator removes the old meter and instead inserts a modern measuring device, he may not charge any costs for it. Because the Measuring Point Operation Act stipulates that the costs for the installation and removal of meters must already be included in the annual measuring price. Many network operators agree to waive an invoice for the meter when registering a plug-in solar device.
If a modern measuring device is installed, the annual measuring costs can rise to the statutory maximum of 20 euros per year.
Make sure that your chosen electricity supplier or the basic supplier does not charge twice the measurement costs within the framework of the basic price for the purchase of electricity.

10. What should I consider when buying?

You should only buy ready-to-install devices.
It is technically very important that the included inverter contains a declaration of conformity according to VDE AR 4105, only then may it be operated on the mains.
In individual cases, companies sell devices, for example, with open cable ends without a connection plug. Customers should apparently mount the plug themselves here.
As a result, manufacturers transfer responsibility for the completion of the product to the buyers. However, only an electrician may legally do this, but not someone without specialist knowledge. The same applies to the replacement of a socket: This must also be done formally by an electrician.
When buying, we recommend that manufacturers comply with the DGS safety standard (DGS 0001:2019-10) for the plug-in solar device.
Mini solar systems can be purchased from the local photovoltaic specialist. However, most offers are available in specialized online retail. Market overviews can currently be found on these websites:
PV magazines (photovoltaic journal)
Pvplug.de (German Society for Solar Energy e.V.)
Meanwhile, there are also offers at discounters or electronics markets. However, these are usually significantly more expensive than the specialist trade offers, and the advice and selection are rather limited there.

If all the requirements are met, you can plug in the device yourself. In some places, DIY workshops, which are carried out, for example, by regional energy cooperatives or other initiatives, and people from the neighborhood who have already gained their own experience with plug-in solar devices, also help.

11. How do I know if it works and how much it does?

Solar modules or module inverters themselves do not directly indicate the functionality or current power. Sometimes the inverters have an LED that signals certain operating states by flashing or lighting. However, this is not enough to detect whether the device is running properly and what performance it delivers.
Some inverters include a power measurement, which you can read and save with the help of an external additional device. This may also work with an online connection to an Internet portal, similar to photovoltaic systems (monitoring). Then the power generation can also be partially read on the mobile phone.
When connected via a Schuko plug in the socket – if this is permitted for the purchased device – you can use a commercially available current meter, as it can also be plugged between the socket and the refrigerator to determine the power consumption. Many of these devices can also measure in the opposite direction and are therefore also suitable as a generation counter for a plug-in solar device.
According to the same principle, so-called “intelligent sockets” work, which can be switched via WLAN from the router or smart home controls and often also include energy measurement.
Both current meters and intelligent sockets are not yet available for connection via the so-called “Wieland” special plug. In this case, you can have a small electronics installed in the socket to collect the data. This electronics also measure the current flow and send it to the Internet router or smartphone via Bluetooth or WLAN.
If solar modules and inverters have become obsolete, you can hand them over to the local recycling yard or point of sale for disposal and recycling.

Checklist: Step by step to the plug-in solar device

  • Are the local conditions suitable for connecting a plug-in solar device? Is there as much sun as possible there?
  • Are the installation location, the socket and the circuit up to date?
  • Do landlords or communities agree?
  • What are the requirements of the network operator and the possible sponsor?
  • Have you found the right offer that meets all requirements? (Technology, price/performance, delivery, assembly and connection, DGS safety standard/future device standard)
  • Have you thought about monitoring to check performance?
  • Do you have experts or a local self-assembly at hand that you can ask in case of doubt?
  • Is everything clear with the registration and a possibly necessary meter exchange?
This content was created by the consumer centers of North Rhine-Westphalia and Rhineland-Palatinate for the network of consumer centers in Germany