For most, the dark winter months, when there are very few daylight hours, lots of snow and cold, probably don’t sound like the most ideal conditions for producing electricity using solar cells. However, there are more possibilities than one might expect. In fact, snow and cold can actually help when it comes to electricity production.
Between 2016 and 2018, the number of grid-connected photovoltaic systems in Sweden increased from about 10,000 to just over 25,000, and the power generated from such has nearly tripled from, 140 MW to 411 MW. Most of these types of facilities are located in southern Sweden, with more than 90% in electricity zones three and four. The same applies to the power generated by them. In project SunCold, RISE is formulating the guidelines on how to install solar panels in the northernmost regions of the country.
– “There is much interest in solar energy even in northern Sweden. However, we lack both knowledge and experience in how to use solar energy efficiently at higher latitudes,” explains Malou Petersson, Project Manager for SunCold at RISE.
Producing solar electricity in regions of the far north is challenging. During December and January there is no sunlight at all and even during the rest of the year the conditions are quite different compared to the major markets for solar energy.
– “Because the sun is so low on the horizon, we need to investigate different angles for the positioning of solar panels in order to derive maximum capacity. And, in countries that are very far north, the light from the sun must travel a greater distance through the atmosphere, compared to how it is for countries near the equator for example. The intensity of sun rays is lower at high latitudes. The composition of the sun rays is also affected. Here in Sweden, approximately half of the light we get is diffuse. In other words, it is scattered and comes from all directions. It has neither the intensity nor the glare of direct light. We must therefore optimize solar cells accordingly,” explains Malou Petersson.
Besides the darkness and low height of the sun, snow and cold are two additional factors affecting the production of solar energy in northernmost places. But the impact is not just negative.
– “For silicon solar cells, the cold temperatures actually have a positive impact on their performance. In fact, with a drop in temperature of 25 C, the power they produce increases by 10 %. We’ve verified this at our test facilities, particularly during spring when there is much more daylight, but temperatures are still low,” says Malou Petersson.
Vi vill öka intresset för att använda solenergi
Advantages and disadvantages of snow
Snow can also have a positive effect on the energy production from solar cells. When the ground is white and covered in snow, more sunlight is reflected and it can be used for energy production. However, for that to happen, the modules holding solar panels must be designed in a special way. Malou Persson explains:
– “With double-sided modules, we can also make use of the sunlight that is reflected, thereby increasing production. We are studying this very thing at our Solvåg solar farm in Piteå,” she says.
However, snow can also present a variety of problems. If snow accumulates on the modules, it blocks the sun rays resulting in a loss of as much as 20 % of their annual production. The design of the modules must thus take that into consideration.
Base for informed decisions
Solar modules can break from the weight of snow and ice accumulation. In the worst case, load-bearing roof structures could also get damaged. RISE is also studying the various effects of snow load on solar modules, with the aim of coming up with recommendations on how solar plants should be designed in different snow load zones, then, getting those recommendations implemented in the standards.
– “Snow can damage the modules in several ways. There can be obvious structural damage as well as microcracks that are impossible to see with the naked eye, yet which anyway can have a significant negative impact on production,” says Malou Petersson.
The objective of efforts concerning solar electricity in the far north is to create guidelines and establish best practice, with a focus on public buildings and the housing sector. Once property owners, municipal authorities and housing cooperative associations have information on the types of solar systems that should be used, based on the conditions, they will be able to confidently make good decisions on how to invest in solar energy.
– “We want to increase the interest in using solar energy in the housing and public sectors. The solar energy market in Norrbotten has also benefitted from the new knowledge, expertise and collaboration that has occurred,” concludes Malou Petersson.
On November 1, 2011, Sweden was divided into four electricity zones, which sometimes have different electricity prices.
Electricity zone 1: Norrbottens county and parts of Västerbottens county .
Electricity zone 2: Jämtlands county, Västernorrlands county samt delar av Dalarnas county, Gävleborgs län and Västerbottens county.
Electricity zone3: Gotlands county, Stockholms county, Södermanlands county, Uppsala county, Värmlands county, Västmanlands county, Örebro county, Östergötlands county and parts of Jönköpings county, Hallands county, Kalmar county, parts of Västra Götalands county, Gävleborgs county and Dalarnas county.
Electricity zone 4: Skåne county, Blekinge county, Kronobergs county, and parts of Kalmar county, Hallands county, Jönköpings county and parts of Västra Götalands county.
Learn more about electricity zones at Svenska Kraftnät.