Plug-in solar energy is emerging as a disruptive solution in the European photovoltaic market. These systems, also known as balcony solar, micro-PV, or plug-and-play solar, allow users to generate electricity from their homes without the need for professional installation.

According to a report by SolarPower Europe, Germany has led the adoption of this technology with more than 780,000 systems registered, and estimates suggest up to 4 million units in use, many of which are unregistered, posing regulatory and technical challenges. The solution typically consists of one or two solar PV modules, which are plugged into a standard grounded electrical socket. A common type of plug-in solar is “balcony solar.” In some European markets, plug-in solar can cover up to 25% of a household’s annual electricity needs.

Alongside the growth of plug-in solar, small-scale battery storage solutions (1-5 kWh) for plug-in systems are also on the rise in Europe, and the number of small batteries (under 2 kWh capacity) multiplied by 24 between 2023 and 2024 in Germany.

While Germany leads adoption, other European countries are following its example. France, Austria, Lithuania, and the Netherlands have seen significant growth in the installation of these systems. In 2025, Belgium will officially legalize the use of plug-in solar, further facilitating its expansion in the region.

However, Spain and Sweden face regulatory challenges. In Spain, connecting plug-in solar systems requires additional devices to prevent energy from being injected into the grid, adding costs and complexity. Sweden, on the other hand, prohibits the use of standard sockets for power generation, hindering mass adoption.

An Expanding Market with Regulatory Challenges

The concept behind plug-in solar is simple: connect one or two solar panels to the household circuit through a micro-inverter and a standard plug, allowing prosumers to install their own generation systems. However, its exponential growth is generating debate among regulators. While Germany and Lithuania allow surplus energy to be injected into the grid without additional certification, countries like Spain and France require administrative procedures or specific devices to prevent injection.

According to SolarPower Europe, this trend could transform access to renewable energy, facilitating adoption by renters and low-income households. However, safety and quality standards are still in their early stages, prompting initiatives like the creation of specific regulations in Germany by VDE, expected in 2025.

The EU and national governments are increasingly recognizing the potential of plug-in solar energy, with new policies emerging to adapt to market realities. Belgium is expected to legalize plug-in solar in April 2025, while Germany has taken significant steps to simplify registration on the electrical grid for this type of energy.

Leah Le Pénuizic, the project director of the report, stated, “It is important to highlight that, with the rise of plug-in solar, Europe needs clear product standards and consistent installation guidelines to ensure safety, grid compatibility, and consumer trust.”

Prices and Market Trends

Market growth has been driven by a drastic reduction in prices in recent months. While the average price of a one-module kit (~400W) used to range between €300 and €500, some products in the German market now start at just €200 and go up to €1500 for larger or more sophisticated systems, or even more if they include battery storage.

Some startups also offer refurbished second-life solar modules for use in plug-in or balcony systems.

“A plug-in installation can contribute between 5% and 25% of a household’s annual electricity needs, with a payback period ranging from 2 to 6 years, depending on the product cost, system size, local solar irradiation levels, module orientation/inclination, and local energy prices,” the report states.

Advantages and Concerns of Plug-In Solar

Highlighted Benefits:

• Affordable access to solar energy: The low cost of plug-in photovoltaic solar energy compared to standard systems and its reasonable payback period enable a wider segment of society to invest in renewable energy generation.
• Ease of installation, with no need for specialized technicians.
• Low initial investment, with a relatively quick return on investment.
• Higher social acceptance of solar energy as it is a visible and accessible technology.

Main Challenges:

• Limited self-consumption capacity due to the small size of the system and not always optimal panel placement.
• Competition with traditional solar systems, as many plug-in installations occupy spaces like terraces or garages where larger systems could be installed.
• Lack of clear regulation, which hinders product standardization and integration with the electrical grid.

“While plug-in solar has a limited impact on the grid, its rapid adoption and the large number of unregistered systems raise concerns among system operators,” said Raffaele Rossi, an energy markets expert.