Solar thermal collectors on the roof of a Finnish home. Credit: Aalto University.

Finnish researchers at Aalto University claim renewable energy could be used to cover 53–81% of the annual domestic heating in the frosty country. The results are considered valid for Scandinavian countries but, in principle, could apply to other locations at the same latitudes, keeping in mind local conditions.

In the European Union, heating takes up the most energy in a household, around 40 percent. In Finland, where average temperatures range from – 22 to -3°C in its coldest months or even down to -50°C in the northern part of the country, heating accounts for more than 80% of a household’s total energy use. Finland’s vision is to become a carbon-neutral society by 2050.

Finland — a country that warms twice as fast than the global average – has a vision of becoming a carbon-neutral society by 2050. The plan is to have 60 percent of its energy use covered by renewable sources by then. Coal is to be scrapped entirely by 2030. Right now, the country employs a diverse basket of energy sources like nuclear power, natural gas, coal, oil, peat, hydropower, and wood-based fuels.

Solar is the least represented energy source in Finland but is growing fast thanks to a drop in prices for solar panels. Finland’s total PV capacity rose from 11.2 to 14.7 MW in 2015, marking a 33% year-to-year growth.

Traditional use of oil or wood-based burners for heating water and the living space is still common, though, which is why the Finnish government is looking towards renewable energy to meet its emission reduction targets.

One might think that Finland will never become a solar energy-intensive country seeing how its polar nights during the winter never stop. But remember Finland is also called the Land of the Midnight Sun where nature replies with 24 hours of full-blown sunlight in the summer. And contrary to popular belief, solar performance isn’t deteriorated by cold weather. On the contrary, panels are significantly more efficient in cold weather and clean, dustless surroundings, as seen in Finland. Finland has about the same amount of annual insolation as northern Germany, a country which has proven itself as a solar energy powerhouse. As long as you have means to store all that sunshine for the gritty winter months, Finland can count on solar — and that’s not just for electricity but heating also.

Unlike PV panels that collect electrons generated by photons hitting semiconducting materials, solar heating works by using the sun’s thermal energy to heat fluid (water or air) in solar collectors. Researchers at Aalto University led by Professor Kai Sirén run the numbers to see just how much Finland can rely on solar for heating its homes.

The results were extremely encouraging suggesting Finns have enough sunlight to ditch oil or wood burners in favor of solar thermal collectors.

“Solar energy offers economically sensible solutions for the collection of energy for this purpose, and for the reduction of carbon dioxide emissions, especially in southern Finland where the majority of the population lives,”  Sirén said.


Scientific Reference: Hassam ur Rehman, Janne Hirvonen, Kai Sirén: A long-term performance analysis of three different configurations for community-sized solar heating systems in high latitudes. Renewable Energy 113 (2017) 479-493.