Up until now, solar photovoltaic (PV) green energy production has been in the hands of large solar developers and/or homeowners able to afford placing full-size solar panels on their houses.  

With the commercialisation of plug-in solar technology, green power generation is becoming increasingly accessible to energy consumers living in apartments and other rental properties. Across Europe, the trend is becoming visible in countries where regulation of this nascent market segment is leading the way.  

The largest market by far is Germany, where the trend of owning a ‘balcony power plant’ (Balkonkraftwerk) which plugs directly into the domestic mains electricity is driving demand among climate-conscious energy users. Last year saw a record-breaking 435,000 new device registrations in Germany, totalling 426 MW capacity, according to Germany’s solar industry association BSW Solar.  

German installations have now surpassed the one million mark. In the four months to April, 135,000 new systems were installed, a 36% rise on the same period in 2024. Capacity installed over this period rose by 75% year-on-year.  

‘Plug-in solar devices are a popular entry into the solar world, partly because of the possibility of commissioning them yourself and the comparatively low purchase costs,’ says Carsten Körnig, Managing Director of BSW Solar. ‘Over the past two years, there has been an increased number of new plug-in solar devices being commissioned during the summer months. We expect this trend to continue this year.’  

The number of devices registered in 2024 in Germany outstripped those added in all previous years combined. A survey carried out in May by pollster Verivox among a 1,000 Germans showed that 17% of them were planning to purchase a plug-in solar system, while 9% had already done so.  

Ease of use 

Usually made up of one or two modules, plug-in solar devices are connected directly through a home’s power socket. The power generated is immediately used by the household’s daytime appliances, such as the refrigerator, Wi-Fi router, television or washing machine.   

While they are an increasingly popular spot for mobile solar modules, balconies are not the only location for plug-in devices. Garages, gardens, sheds, terraces and facades are also increasingly chosen as suitable locations.   

At an average cost of €300–500 for a one-module kit of around 400 Watts, plug-in solar systems are more affordable than traditional PV panels, opening the market to those with less disposable income. In Germany, some products start as low as €200 and can go up to €1,500. Devices are easily obtainable online or increasingly found in DIY shops and other large retail outlets. Buyers can install the components themselves.

‘The legal improvements [in Germany] in recent years have led plug-in solar devices from being niche products to becoming real consumer products.’ – Carsten Körnig, Managing Director, BSW Solar

The opportunity for self-sufficiency is also a factor often mentioned by buyers of plug-in solar systems. The modules can cover 5–25% of a household’s yearly electricity consumption, giving a payback time between 2–6 years on average, according to Solar Power Europe.  

‘The advantages of my plug-in solar system are the uncomplicated setup and the reasonable purchase price. Furthermore, the technology requires no maintenance and significantly reduces the electricity bill,’ says Thomas Becker, owner of a balcony power plant who is living in a suburb of Bonn.  

‘People’s interest is clearly palpable. Many are looking to make their own contribution to protecting the environment without having to dig too deep into their own pockets, while others are looking to reduce their own electricity costs and many people also appreciate having an option for emergency power supply in the event of a power outage,’ he adds.  

As plug-in solar systems are becoming more sophisticated, more modern solutions like battery storage add-ons or off-grid functionality are being offered, albeit at an additional cost. In Germany, the amount of installed battery systems with an output of less than 2 kWh – the type typically linked to plug-in solar devices – saw a 24-fold increase in the year to end-2024, to more than 30,000 units, according to government data.   

If installations are proving so popular in Germany, why are plug-in PV devices not rolling out more quickly in other markets?  

Limitations 

The technology also comes with limitations that prevent it from seeing exponential growth elsewhere. For example, micro-PV devices installed in small apartment spaces are not always optimally oriented to absorb sunlight most efficiently. The popular balcony location mostly requires modules to be placed at a 90° angle which is not optimal for irradiation, and balcony spaces are often shady.  

Traceability is another issue. Registrations of plug-in solar devices in Germany only started in 2020, meaning there is limited data available on installations. Academic research from HTW Berlin estimates that German plug-in solar numbers could be as high as four million as the amount of unregistered devices is thought to be quite significant.  

The lack of harmonised safety standards is also preventing roll-out in countries such as Sweden and Hungary, where the devices are currently illegal. Belgium legalised their use only in April 2025. In the UK, plug-in solar panels are currently illegal. But the government’s ‘solar roadmap’ published in late June states that it is commissioning a safety study ‘with the aim of unlocking opportunities for plug-in solar over the next few years’.  

With a typical installation capacity of less than 800 Watts, most plug-in solar devices fall outside of the remit of the EU Network Code Requirements for Generators (RfG).  

The issue is trying to be addressed by Germany’s technical regulator VDE, which is in the process of developing the world’s first product standard for plug-in solar systems. It includes standards for basic protection and electrical safety that are being fine-tuned in a new draft.  

‘We are currently in the final stage of the process, which is arbitration. The arbitration hearings will be completed in June, and only then will we be able to determine how the product standard will proceed,’ a spokesperson for VDE said.  

Regulation 

The European Union (EU) is also in favour of allowing the roll-out of plug-in solar devices in line with its renewable energy ambitions. Last year’s update to the EU’s electricity market design directive stipulates that European regulators should set network tariffs low enough to incentivise plug-in solar technology.  

As the EU’s largest plug-in solar market, Germany made a number of regulatory changes last year to address this growing segment of the solar PV market. The SolarPaket 1 package from May 2024, for example, featured a simplified registration process, with a single point of contact for the federal network regulator’s Core Energy Market Data Register. Separately, German rental law was adjusted in October 2024, allowing tenants and flat owners the right to obtain approval from their landlords or housing associations to install plug-in solar systems.   

A recent German court case from April 2025 also set a precedent for the use of plug-in solar devices in allotments, after a judge ruled that the growing use of renewable energy was more important than the concerns of an allotment association.  

‘The legal improvements [in Germany] in recent years have led plug-in solar devices from being niche products to becoming real consumer products,’ notes BSW Solar’s Körnig.  

Other markets 

The lessons learnt from early adapters in Germany are giving valuable insights into how to stimulate growth of micro-PV in other countries.  

‘Given Germany’s role as a pioneer and worldwide leading market for this technology in the past, a quickly evolving regulatory framework and the ongoing development of the first product standard for the technology... there is a solid blueprint to learn from when striving to enable plug-in PV growth in other EU markets,’ says Solar Power Europe in a recent report.  

Other markets such as Austria and Lithuania have seen installations of plug-in solar devices grow and have published data to reflect this. In Austria, around 20,000 systems were registered last year, while Lithuania estimates 350 users of plug-in solar devices have been registered.  

The Belgian market is expected to grow rapidly following the legalisation of plug-in PV installations in April. ‘We estimate that “plug and play” systems (PV and batteries) could reach 1–2% of Belgian households within the first 12 months – roughly 50,000 to 100,000 units. We expect the local growth to remain somewhat below the levels seen in Germany during its first years after regulatory simplification,’ comments Arnaud Etienne, co-Founder of Pluginfo, a website about plug-in solar devices supported by non-profit renewable energy organisation EF4.  

Solar market experts in the Netherlands are also seeing growing demand for plug-in solar technology in the residential market, but legislation is slow to adapt to give sufficient impetus.  

‘In the Netherlands, we are short of space when it comes to solar and energy can be expensive especially for people living in apartments... Plug-in solar solutions, and the balcony set-ups in particular, offer a nice outcome for them so they can take control of their own energy bill. But we do see some hesitancy in adopting the technology,’ says Gijs de Koning, Editor-in-Chief of Dutch solar PV publication Solar 365.  

Subsidies 

Some nations, including Germany, Austria and Lithuania, have already started to incentivise the use of plug-in solar systems through support mechanisms. Typically, this is a means to quickly encourage fast growth in a new sector. In Germany, for example, various local governments have schemes in place that subsidise some of the upfront purchase and installation costs. Lithuanian plug-in system users are entitled to net metering of power produced by their devices.  

With legislation adapting to the growing use of micro-PV across Europe and with prices for plug-in kits falling as installations rise, apartment dwellers in more and more countries will likely turn to this relatively simple means of self-sufficient green energy production.  

• Further reading: ‘Europe’s solar dilemma: Competing with China while securing energy independence’. In the early 2000s, Europe was at the forefront of solar PV production. However, as governments scaled back subsidies and incentives, they failed to compete with China’s state-backed manufacturing surge. Since 2011, China has invested over $50bn in new PV supply capacity – 10 times more than Europe. Making a dent in China’s production monopoly will be immensely challenging. But the EU could maintain leadership in solar installation and technology by strategically directing funding and diversifying supply chains, for example in the bloc’s upcoming Clean Industrial Deal. 
• Solar is providing power to more people in more parts of the world than ever before, a new report from SolarPower Europe reveals.