With winter months approaching, solar owners in South Africa are starting to observe changes in the output of their systems. According to data from Matthew Cruise, the head of business intelligence and public relations at Hohm Energy, solar output decreases by more than 50% in the Western Cape, whereas, in Gauteng, it is largely unaffected. However, although there are some noticeable differences, Cruise assures that the changes are not extreme and that South Africa is still one of the best places in the world for solar.
Why does winter cause lower solar output?
The output of solar systems generally decreases in winter months for several reasons:
- The sun’s path is lower in the sky in winter, which means that the panels’ tilt angle would need to be higher to perform optimally. The optimal tilt angles on a solar panel is between 25 and 35 degrees, but in winter, it may need to be higher.
- In winter, there are generally more days with cloud cover, resulting in panels receiving less direct sunlight.
- The days in winter are shorter, meaning that solar panels start producing energy later in the day and finish earlier.
However, although winter conditions cause some problems, there are also some benefits for solar panels output. For instance, the efficiency of solar panels decreases slightly at hotter temperatures.
Factors affecting solar output that can be controlled:
Solar output is not entirely out of one’s hands; there are a few factors that solar users can control. These include ensuring that panels are clean, no objects that throw shade onto the panels, and deciding which direction to face the panels.
For Southern Hemisphere countries such as South Africa, it is best to have north-facing panels because these generate the most power.
Province-by-province data on solar output change in every month
Hohm Energy conducted a test, which gave an indication of the change in expected output of solar panels for every month in the year for each province, using the same brand and quantity of panels and inverters, each with a 25-degree tilt directly facing north. Here are the results:
- Gauteng: The peak output months for Gauteng are in August and October, and the level of output is reasonably flat throughout the year.
- Western Cape: The November to January months are the highest output months for the Western Cape, with higher output than the best months in Gauteng. However, solar output in the Western Cape tapers off massively in winter months, with a 52% decrease in June compared to January.
- KwaZulu-Natal: In KZN, output is reasonably stable and slightly lower than the best months in the Western Cape. There is a 18% difference between the best and worst output months.
- Northern Cape: Production in the Northern Cape peaks in the summer months and comes down 25% in June from the January high.
- Mpumalanga: Solar output in Mpumalanga is higher in the winter months than in the summer months.
- Limpopo: Output in Limpopo is reasonably consistent, with only a 7% spread between the highest and lowest months.
- Free State: There is a 17% gap between the lowest and highest months, with six months of very strong output.
- North West: The output is reasonably consistent throughout the year, with peak months between August and October.
Solar systems’ output will decrease in the winter months in the Western Cape but stay relatively unaffected in Gauteng. However, it is important to note that the changes are not extreme, and South Africa is still an excellent place for solar. With the correct direction and cleaning, solar energy can still be an efficient and economic solution for households and businesses alike.