Solar Energy Potential Sweden
When we talk to people about our plan to move to Sweden one of the topics that almost always comes up is solar energy. Does it make sense to invest in solar panels in a country that has long and dark winters and that is often covered under a layer of snow?
If you want to live off grid you need to find a source of energy that can provide you with sufficient power. For us the first thing that comes to mind is solar power. But we have no clue whether this makes any sense in Sweden, be it financial or practical. Of course Sweden has long and dark winters but in the summer the sun doesn’t set (depending on your latitude). Surely those long summer days can be used to transform solar energy into power and hot water. But will a solar system alone be sufficient to power our house and heat up our water during winter? In this article we take a closer look at the expected output of solar panels at northern latitudes.
Solar Energy Potential
A few hours on Google resulted in finding the website of the Joint Research Centre of the European Commission’s Institute for Energy and Transport. Even though it seems that the information on this website was last updated in 2014, we still found some useful information.
Above image gives a clear view on the difference in solar energy potential between the higher latitudes and the Southern part of Europe. Focusing on Sweden we see that the global irradiation in the largest part of Sweden varies between 1,000 and 1,100 kWh/m2. This is the yearly sum of global irradiation on optimally-inclined south-oriented solar panels. The map also shows us that based on a 75% performance, the yearly sum of generated electricity by an optimally-inclined 1 kW-system varies between 750 kWh and 825 kWh.
Challenges at northern latitudes
Above images all show the theoretical annual solar energy potential. There is no differentiation between summer and winter potential while we know that higher latitudes have long summer days and at very high latitudes even completely dark days during the winter. Another Google search resulted in finding this 2012 article from ScienceNordic. According to the researchers there’s great potential for solar energy at northern latitudes but there are some extra challenges to be dealt with:
- For the best output, the solar panels shouldn’t be placed in a fixed position. The further north you are, the wider the arc of the sun across the summer sky, from northeast, via the south to the northwest. In order to follow the sun the solar panels must rotate as well as tip to face the at a 90° angle;
- A sun-tracking solar panel needs to be a certain size to be cost effective and it requires the best (and most costly) silicon cells;
- The good news: the snow reflects the sun when the solar panel is surrounded by snow. The bad news: the snow also lands on the panels, blocking the sun and it can also clog and ice up the machinery that rotates and tilts the panels.
And there’s more good news: it’s usually colder at northern latitudes and solar panels are more efficient at lower temperatures.
alternative energy source
After this first very preliminary “research” it seems that solar is definitely worth looking at, even at northern latitudes. But for year-round off grid living it seems we have to invest in a lot of solar panels that are mounted on an expensive rotating and tilting system if we want to make the most of the solar energy potential. Our first instinct says it may be better to install a smaller (and cheaper) fixed system adjusted to our energy needs in spring, summer and fall. And to look into a second energy source to complement the solar panels during the dark winters. Of course this is a very preliminary conclusion and we will definitely dig into this subject further in future posts.