The most important questions and answers on the subject of mini solar systems at a glance

Go to the hardware store, buy a mini solar system and connect it at home… sounds good, but is it really that easy? Since 2017, operators of such solar systems no longer operate in the legal grey area but are officially allowed to use the solar systems at home. But what exactly are these mini solar systems all about? Does such a small solar system even make sense? Do I have to observe certain regulations? Find out everything worth knowing about the sun harvest in your own four walls.

  • How does a “small” solar system differ from a “big” one?
  • How is a mini solar system constructed?
  • Installation of mini solar systems – Where can I install a mini solar system?
  • Legal aspects: Is it permissible to connect a mini-PV system to the household electricity network via the socket?
  • How do I know if my mini solar system is working properly?
  • What are the electricity meter regulations for mini solar systems?
  • How much does a mini solar system cost?
  • Is a mini solar system worthwhile for the garden house?
  • Conclusion: sunny prospects

Due to the high demand, we have updated this article and added the question “Is a mini solar system worthwhile for the garden house?”.

How does a “small” solar system differ from a “big” one?

Basically, mini solar systems and photovoltaic systems have the same purpose: to collect solar energy, convert it into electrical energy and then use it as electricity. A mini solar system is essentially a miniature conventional PV system.
In comparison to a large PV system, however, plug-in solar devices have the following special features:

  • Small and compact
  • “Plug & Play” (independent assembly, installation, use)
  • Electricity for self-consumption in the house electricity network or as an island system with a battery
  • Mobile and flexible in assembly and operation
  • Rated power: 600 W (0.6 kWp)
  • Independent registration with the network operator and market master data register
  • ImageWhat is the best way to capture the sun’s rays?

The special feature of mini solar systems, in addition to their size and compactness, is that they are designed according to the “Plug & Play” principle. With these “small” solar systems, everything from assembly and connection to use should be able to be carried out independently by private individuals. They are mainly developed for self-consumption and only feed electricity into the house electricity network or into a small battery.
With photovoltaic systems on private houses, on the other hand, sufficient electricity can be generated to feed it into the power grid. The installation and maintenance of the components of such a “large” solar system must be carried out by a specialist company. This also takes care of the registration with the network operator, which can be carried out by the consumer himself in the case of mini solar systems.
The systems also differ in their mobility and flexibility. PV systems are installed on the roof for permanent operation and can only be removed and moved to another building with great effort. Mini solar systems, on the other hand, can be installed on balconies, terraces, on facades or in a sunny spot in the basement and can be easily removed and operated at another location.
While mini solar systems usually consist of one or two modules with a nominal output of 300 watts each, PV systems are made up of several modules and produce between 3 and 20 kilowatts.
Note: Mini solar systems are also known as plug-in solar devices, plug-in solar systems, balcony power plants, balcony modules, mini PV systems and guerrilla PV systems.

How is a mini solar system constructed?

A mini solar system usually comes in a set with the following components :

  • solar panel
  • mounting frame
  • inverter
  • battery
  • Plug and cable for the socket

A plug-in solar system usually has one or two solar modules that can be flexibly combined. An inverter converts the direct current generated by the solar system into alternating current so that the current can be fed into the 230-volt household power supply. For off-grid systems that are not connected to the domestic power grid, the inverter function should be able to switch off automatically.

Tip: If you would like to evaluate your yield data and the performance curve of the solar system, opt for a set with a display and Ethernet connection on the inverter. You can use software to visualize your energy yield.

How big and how heavy are mini solar systems?

The standard format of such a solar module is 1 MX 1.70 m with a typical nominal output of 300 watts and a weight of up to 20 kg.
In addition to the standard modules, smaller and lighter solar modules with outputs of 50-150 watts are also available. These are suitable, for example, for mounting on balcony parapets. However, two to four of these modules must be connected to an inverter for it to work efficiently.

What does Wp or Watt Peak mean for a solar system?

Since the performance of a solar system depends on the solar radiation, it varies greatly depending on the day, the weather and the time. In order to have a comparable nominal output, the peak output and thus the output under standard conditions with full solar radiation is specified with “Watt Peak” (in short: Wp).
The power actually generated often deviates from this value depending on the weather conditions. As a guideline, a mini solar system with 100 Wp achieves an output of 90 kWh of electricity per year.

Installation of mini solar systems – Where can I install a mini solar system?

In order to be able to harvest solar energy ideally, it is first necessary to find a sunny place where the solar module or modules can be attached.
Mini solar systems can be mounted in many places such as:

  • balcony
  • terrace
  • facade
  • garden
  • roof

The purpose of a mini solar system is that the consumer can connect it almost intuitively and save installation costs. The systems are therefore usually designed in such a way that the installation can also be carried out by non-professionals.
The mounting frame supplied is an elevation triangle made of aluminium or steel. Not only do they provide secure support, they also ensure the tilt that allows for the best possible yield. Although environmentally friendly frames made from recycled paper reduce CO2 emissions, they can have a negative impact on the yield of the solar module.
Tip: Make sure that the screws are tight and that the mounting frame offers a firm hold even in strong winds.

Legal aspects: Is it permissible to connect a mini-PV system to the household electricity network via the socket?

no . In some EU countries, it is permitted to plug the plug-in solar modules with an output of up to 600 Wp into a normal household socket. In Germany, however, a special power connector is required according to DIN VDE 0628-1. This is a so-called feed socket. In Germany, the so-called Wieland socket and the associated Wieland plug have become established.
If the mini solar system is not used as an island system but is fed into the domestic power grid, not only does the power socket have to be installed by a specialist, but they also check the existing circuit and replace the fuse if necessary.
This topic is still controversial in Germany. While some consider the connection of solar systems with up to 600 watts to the normal socket to be harmless, others warn against it. Technology for the direct transmission of energy via solar radiation has not yet been developed.
The German Society for Solar Energy (DGS) advocates simplified regulations and demands official permission to operate mini solar systems via a Schuko plug. Associations such as the VDE advise caution and generally recommend having the installation carried out by a qualified electrician.
Note: Never connect several mini solar systems via multiple sockets. A separate socket must be provided for each mini solar system to prevent overloading of the power line and cable fire.

How do I know if my mini solar system is working properly?

Everything mounted, connected, in operation… and now? The solar modules themselves and also the inverter does not show directly whether a solar system is working properly and how much it is doing.
Some inverters have an LED that lights up or flashes to indicate certain operating states. However, it does not show if a device is working properly and how much it is performing. If your inverter has a power measurement, you can read out, save and evaluate the performance data externally.
Alternatively, the power can be measured via the socket. Plug a standard power meter between the socket and the consumer – for example, your refrigerator. Depending on the power meter, you can not only determine the power consumption of the refrigerator but also measure the power in the opposite direction and thus determine the power generated. Intelligent sockets, such as those used in smart homes, often have an energy measurement function.
If you use a solar module with a connection using a Wieland special plug, there are still no compatible power meters and intelligent sockets. In this case, small measuring electronics can be installed in the socket, which measures the current flow and transmits the measurement data to a terminal device via WLAN or Bluetooth.

What are the electricity meter regulations for mini solar systems?

Bidirectional meter – Do you also have electricity flowing in all directions?  mini solar systems
Bidirectional meter

If you connect your mini solar system to your home electricity network, there are also special regulations regarding the electricity meter. Your electrical installation must have a counter with a backstop or a bidirectional counter.
The background is as follows: Especially on particularly sunny days, you may not be able to fully use the electricity generated by your small solar system. If there is a connection to the domestic power grid, your excess electricity flows into the public power grid.
In this case, a conventional counter without a backstop simply rotates backwards and that is forbidden in Germany. Because the price for the electricity consumed (approx. 30 cents per kWh) is significantly higher than the value specified in the EEG feed-in tariff (11 cents per kWh). You would get your excess electricity reimbursed for a much higher price through the return function.
In the case of a meter with a backstop, the meter reading cannot be reduced by electricity fed into the grid. If you would like to record the current fed into the grid, we recommend installing a bidirectional meter. It is designed to measure consumed and fed-in power separately.

How much does a mini solar system cost?

In recent years, the prices of solar modules have fallen sharply, so energy generation using photovoltaics is becoming increasingly affordable. With mini solar systems, the step towards environmentally friendly electricity seems even closer. The market for mini solar systems is growing and some models are available for as little as €300.
However, if you are looking for a high-quality and safe product, you should expect costs of between €400 and €1000. The German Society for Solar Energy (DGS) offers a market overview with performance data, manufacturer and price.

Is a mini solar system worth it and when will it pay for itself?

For maximum performance, the sun’s rays must fall as vertically as possible. The right location is therefore essential for a quick return on investment. As a guideline, a good mini solar system with 100 Wp can be expected to yield 90 kWh of electricity per year.
For an estimated amortization calculation, let’s assume a 300Wp mini solar system, which therefore achieves 270 kWh per year. With an average electricity price of around 30 cents per kWh, the mini-PV system offers electricity savings of around €80 per year.
If you have invested a total of €800 in your mini solar system, it will pay for itself after 10 years. Service life of at least 20 years can be assumed for high-quality mini-PV systems.
TipNot only shading but also soiling of the modules can lead to reduced energy yields. Therefore, check and clean your module regularly.

Is a mini solar system worthwhile for the garden house?

Many gardens and garden houses are not connected to the public power supply.
Of course, the purpose of a garden plot is actually to spend some time in the countryside, but for one or the other application, some electricity would be very practical.
While the classic solution for generating electricity is a generator, a mini solar system for the garden house offers numerous advantages:
⦁ Energy is generated from the sun and thus from a renewable energy source
⦁ Mini solar systems are quiet and do not disturb the environment
⦁ Thanks to inexpensive solar systems, no major investments are necessary and the electricity generated by the sun is free
⦁ Plug-in solar systems can be installed quickly and easily
⦁ Very little to no maintenance is required
⦁ Mini solar systems have a long service life of at least 20 years
You often spend time in the garden when the sun is shining and the solar cells are generating electricity. However, if you want to use the solar energy generated during the day in the evening and at night, it is worth buying a battery.
The unused energy is fed into the battery and can be used at a later time. Such an energy store is particularly ideal for evening lighting and for the operation of small electronic devices.

Conclusion: sunny prospects

The concept of the mini solar system offers a simplified way of taking the first steps towards solar energy in your own home without having to make major investments. Mini solar systems are also ideal for stand-alone systems. Above all, they can actually be used according to the “Plug & Play” principle.
If you don’t want to use your mini PV system for the allotment garden or camping trips, but actually want to contribute something to the domestic electricity, you still have a few things to consider. The standard stipulates, among other things, a professional inspection of the domestic electrical installation. In addition, a power socket and the right electricity meter are mandatory.
Even if consumers are still faced with a few obstacles when it comes to repairing their small solar system, the approval of mini solar systems and the relaxation of the law in recent years represent an important step for flexibility and DIY in the field of solar energy.
If you want to protect the environment and at the same time enjoy some independence from the electricity provider, mini solar systems can offer an interesting solution. Will you also follow the sun?