How many solar panels does a balcony power plant need?

How many modules are allowed for a balcony power plant?

A balcony power plant – also known as a mini PV system – is enjoying increasing popularity in Germany and other European countries. But one of the most frequently asked questions is: How many photovoltaic modules are actually allowed? Basically, this depends on the legal framework and the maximum permissible feed-in power. In Germany, the limit is currently 800 watts of inverter power (as of 2024/2025), with many system operators installing two solar modules, each with about 400 to 450 watts.

The number of modules is therefore not directly limited by law, but results indirectly from the maximum permitted power. In practice, two modules have become established as the standard, as they offer a good balance between power, space requirements and costs. If you want to install more modules, you have to register the system differently or operate it as a larger PV system.

How much power should a balcony power plant have?

The optimal power of a balcony power plant depends heavily on individual electricity consumption and local conditions. For an average household, a power of about 600 to 800 watts is recommended, as this can be well integrated into daily basic consumption. Devices such as refrigerators, routers or standby consumers benefit directly from the generated solar power.

A balcony power plant with two 400-watt modules delivers up to 800 watts of peak power under ideal conditions. However, this peak power is only achieved with optimal sun exposure. Realistically, the actual power is significantly lower on an annual average. Nevertheless, such a system can generate between 600 and 900 kWh of electricity annually – a noticeable contribution to reducing electricity costs.

Are two solar modules sufficient for self-consumption?

Whether two modules are sufficient depends heavily on electricity consumption and usage behavior. For singles or small households with low basic consumption, two modules can already cover a large part of the daily demand. Use is particularly efficient when the generated electricity is consumed directly.

For larger households with higher energy requirements, two modules are often just a start. Nevertheless, a balcony power plant is also worthwhile here, as it continuously supplies part of the electricity and thus reduces dependence on the grid. It is important that the generated electricity is consumed as simultaneously as possible, as classic balcony power plants usually do not have a storage unit.

How does the orientation affect the number of modules?

The orientation and inclination of the solar modules play a crucial role in the efficiency of the system. A south-facing balcony with an optimal inclination angle achieves the highest energy yield. In this case, two modules can already deliver very good results.

With east or west orientation, electricity production is distributed more evenly throughout the day, but with slightly lower overall power. Here it can be useful to place modules in such a way that they cover different sun paths. If the orientation is suboptimal, a larger module area can help compensate for the lower efficiency – provided that the legal limits are observed.

Can more than two modules be connected?

Technically, it is possible to install more than two modules, but the feed-in power of the inverter must not exceed the legal limits. Many operators use so-called "oversizing": Modules with a higher total power are connected to an inverter with limited output power.

The advantage is that more electricity is generated even under less optimal conditions (e.g. cloudy skies). However, the power is "throttled" in very strong sunlight. This strategy can be particularly useful in regions with changeable weather.

What role does the inverter play?

The inverter is the heart of a balcony power plant. It converts the direct current generated by the modules into grid-compatible alternating current. The maximum output power of the inverter is crucial here, as it is legally limited.

A typical inverter for balcony power plants has a power of 600 to 800 watts. The number of connected modules must be selected so that this limit is not permanently exceeded. Modern devices also have safety functions and can be easily connected via a socket.

How much space does a balcony power plant need?

The space required depends directly on the number and size of the modules. A standard solar module measures about 1.7 to 2 square meters. For two modules, you therefore need about 3 to 4 square meters of space. These can be mounted on the balcony railing, on the ground or on the facade.

It is important that the modules are shaded as little as possible. Even small shadows – for example from plants or railing struts – can significantly reduce performance. Therefore, planning should be carefully carried out to make optimal use of the available space.

Is a balcony power plant financially worthwhile?

The acquisition costs for a balcony power plant range between 400 and 1,200 euros, depending on quality and performance. With an annual electricity production of about 700 kWh and an electricity price of 30 cents per kWh, this results in savings of about 200 euros per year.

Thus, the system often pays for itself after just 3 to 6 years. Since the lifespan of solar modules is usually over 20 years, a balcony power plant is a long-term profitable investment. In addition, electricity prices tend to continue to rise, which further improves profitability.

Are there differences in module types?

Yes, there are different types of photovoltaic modules that differ in efficiency, price and appearance. Monocrystalline modules are particularly efficient and space-saving, while polycrystalline modules are often cheaper but offer slightly less power.

For balcony power plants, monocrystalline modules are usually recommended, as they deliver high performance even in limited space. In addition, there are flexible or particularly light modules that are suitable for special mounting situations.

Conclusion: How many modules are ideal?

The ideal number of photovoltaic modules for a balcony power plant is in most cases two modules. These offer a balanced combination of performance, cost and easy installation. Those who have optimal conditions can cover a significant part of their electricity needs with them.

Nevertheless, the actual number always depends on individual factors such as space, orientation, budget and electricity consumption. It is important to plan the system carefully and adapt it to your own needs. This way, the full potential of a balcony power plant can be exploited and an active contribution to the energy transition can be made.

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FAQ – Frequently asked questions about balcony power plants

How much electricity can a balcony power plant generate per year?

A typical balcony power plant with about 800 watts of power generates between 600 and 900 kWh per year, depending on the location and orientation. In southern regions or with optimal orientation, production can even be higher.

Do I have to register my balcony power plant?

Yes, registration is mandatory in Germany. The system must be registered in the market master data register of the Federal Network Agency. In many cases, notification to the grid operator is also required, although the process has now been significantly simplified.

Can I store the generated electricity?

Basically yes, but classic balcony power plants usually do not have an integrated storage unit. However, there are now solutions with small battery storage units that have been specially developed for mini PV systems to further increase self-consumption.

What happens to surplus electricity?

Surplus electricity is automatically fed into the public grid. Remuneration for this is generally not provided for balcony power plants, which is why it makes sense to consume the electricity yourself as directly as possible.

Are balcony power plants useful even in bad weather?

Yes, even on cloudy days, solar modules generate electricity – albeit in smaller quantities. Modern modules are so efficient that they still supply energy even in diffuse light and thus contribute to saving electricity costs.