Solar in winter: Expect up to 65% reduction in solar PV generation

During the winter, we normally receive several queries from our customers wondering “What is their solar panel winter efficiency” and  ‘Why their solar PV isn’t working’ and our response to these questions is the following:

In the winter months, the Southern Hemisphere is tilted away from the sun and receives less direct rays from the sun, but during the summer, the Southern Hemisphere gets more sunlight. Because the sun is more directly overhead in summer months, a solar panel puts out more power than during the winter, when the sun’s rays are less intense, and the days are also shorter.

Similarly, on typical Cape Town rainy days in winter, a solar panel operates at a lower efficiency since it is less exposed to direct sunlight.

To illustrate this, our AWPower engineers provided results from our solar PV design system for a typical 3.6kWp solar PV installation site in Durbanville (Cape Town) where the reduction in generation of electricity is calculated to be as much as 65% from January (688.9kWh per month) to June 2022 (312.9kWh per month).


Due to lower solar generation of electricity during winter months, it is advisable to oversize your solar solution to ensure adequate solar panel output in winter performance during these months.

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