Study: Balcony solar systems almost always pay off – but storage is more complicated

Anker has analyzed its own usage data from Germany and arrived at a clear conclusion: balcony solar systems and mini PV systems can significantly reduce household electricity costs. While the benefits of the solar systems themselves are fairly clear-cut, the picture looks different when additional battery storage is involved. According to Anker, the analysis is based on a random sample of around 230,000 households in Germany from 2025. The data comes from systems belonging to users who had consented to data processing. The full white paper, titled From Balcony Power Plant to Energy System, is not freely available, however, and can only be obtained on request.

The core takeaway for a standard balcony solar system is clear: it almost always offers an economic benefit. Based on the white paper, Golem (a German outlet) reports that a system limited to 800 watts of inverter output can generate almost 900 kWh per year on average. A common setup with up to 2,000 watts of module output across four panels is said to deliver more than 1,200 kWh. On average, around 40 percent of that is consumed directly within the household.

At an electricity price of €0.30 ($0.35) per kWh, a €500 ($575.85) balcony solar system – such as Solarway’s plug-in PV system with 2,000 watts of module output, currently priced at around €550 ($633.44) on Amazon – would pay for itself in roughly three years and could then theoretically generate around €150 ($172.76) in net savings per year, which depending on the household could amount to roughly two electricity bills. In practice, of course, yield and savings depend heavily on the actual electricity price, system orientation, shading, and base load. Another point to consider is that a balcony solar system is not a completely risk-free purchase. Damage caused by storms, vandalism, or installation errors may not be common, but it is certainly possible. It is therefore worth checking before buying whether your home insurance already covers such cases, or whether the balcony solar system needs to be explicitly added to the policy, which would then need to be factored into the overall calculation. The dollar conversions in this paragraph are based on the ECB reference rate of €1 = $1.1517.

Storage makes things more complicated

Anker also presents storage systems for balcony solar setups in a positive light. According to the company’s press release (in German), the evaluated systems generated a total of 206 million kWh of solar electricity in 2025, 83 percent of which was used directly in the household. The company puts the total savings on electricity costs at €65 million ($74.86 million), with average annual savings of €270 to €360 ($310.96 to $414.61) per household. However, Anker does not disclose how large a storage system needs to be to achieve those results.

Large systems such as the Anker SOLIX Solarbank 3 E2700 Pro, which reaches 5,376 Wh of storage capacity with an additional battery, cost around €2,000 ($2,303.40) when paired with 2,000 watts of module output. That higher upfront cost leads to a significantly longer payback period. Anker speaks of around five years, but bases that calculation on an electricity price of €0.40 ($0.46) per kWh. At lower prices, it could take considerably longer for a balcony solar system to recoup its costs. There is also another factor to consider: solar panels usually come with warranties of around 25 years, while batteries often only carry warranties of about 10 years. That makes a balcony solar system with storage a much more speculative investment that only pays off over the long term and only under favorable conditions.