Finland’s home batteries are not yet an economically viable way for households to store electricity generated by rooftop solar panels, according to new research by the University of Turku and Turku University of Applied Sciences. The study found that high upfront costs, installation expenses and battery degradation still outweigh the savings that Finnish households can make by shifting solar power use to more expensive hours of the day.
Why Finnish solar batteries still struggle to pay back
The research challenges one of the most common assumptions about residential solar power: that adding a home battery automatically improves the economics of a rooftop system. In Finland, where solar power has expanded in recent years, many households have considered batteries as a way to increase self-consumption and reduce exposure to hourly electricity prices.
The study suggests that the financial case remains weak. Even when electricity prices fluctuate strongly, the savings generated by charging a battery when power is cheap or abundant and discharging it when prices are higher are not enough to cover the full cost of the system. Battery wear is a central factor in that calculation, because each charging cycle reduces the battery’s useful lifetime and therefore its long-term value.
According to doctoral researcher Lauri Karttunen from the University of Turku, even annual savings of several hundred euros would not be sufficient under current market conditions. The price of a battery system, including installation, remains too high for the investment to pay for itself within the battery’s lifetime.
Machine learning could not make home battery storage profitable
The researchers also tested whether more advanced battery management could change the result. Algorithms based on optimisation and machine learning were used to improve the timing of charging and discharging, taking into account real electricity prices and household consumption patterns.
The result was still negative. Better timing increased savings, but not enough to make residential battery storage financially profitable. This is important because smart energy management is often presented as a way to unlock new value from small-scale renewable energy systems. In the Finnish case analysed by the researchers, software improvements alone could not overcome the cost gap.
The analysis was based on real solar power production measured in Turku, actual electricity consumption data from four Finnish households, and hourly market electricity prices over three years: 2020, 2021 and 2022. The inclusion of 2022 is particularly relevant, because the European energy crisis produced unusually high and volatile electricity prices.
The 2022 energy crisis was still not enough
The most favourable scenario in the study occurred during the high-price conditions of 2022. Even then, the researchers estimated that a battery would have needed to cost no more than €185 per kilowatt-hour, including installation, to become economically viable. For a 10 kWh household battery system, that would mean a total installed price of no more than €1,850.
That threshold remains far below the cost of many residential battery systems on the European market. Since 2022, electricity prices in Finland have fallen from the peak levels of the energy crisis. Price volatility remains higher than before the crisis, but not enough to make the battery investment profitable under the assumptions tested in the study.
Karttunen also noted that battery prices have not fallen sufficiently since 2022 to alter the conclusion. The finding does not mean that batteries have no role in the energy transition, but it shows that the current economic case for Finnish households remains limited when judged only by direct savings on electricity bills.
What this means for Finland’s rooftop solar growth
The study comes as Nordic households and governments continue to assess how distributed solar power, storage and flexible demand can fit into electricity systems increasingly shaped by renewable energy. Finland’s solar potential is seasonal, with strong generation in the long summer days and much lower output during winter, when electricity demand is often higher.
For households, this seasonal mismatch makes the economics of solar battery storage in Finland more complex than in countries with more even year-round solar production. A battery can help shift electricity use within a day, but it cannot solve the broader seasonal gap between summer production and winter consumption.
The research therefore points to a more cautious conclusion: rooftop solar may still make sense for many Finnish households, but adding a battery is not automatically a sound financial decision. For now, the economics depend heavily on system prices, electricity tariffs, household consumption patterns and the future value of flexibility in the power grid.
If battery prices fall significantly, or if households are paid more directly for providing grid services, the calculation could change. Until then, home batteries in Finland appear more relevant for resilience, self-sufficiency or environmental preference than for short-term financial return.
