Will My Solar Panels Work When It’s Cloudy Or Rainy?
If solar panels generate power from exposure to sunlight, then how do they work on cloudy days? During monsoons, are you left with a fraction of the power that your system produces on sunny days?
Earlier, Insolergy discussed whether solar energy works at night, and now on a similar note of answering a frequently asked question, this article explains how cloudy weather affects the power production capacity of your solar PV system.
What happens to solar power on cloudy days?
Solar panels do not generate power from heat, but from the light received directly from the sun.
This means that as long as the panels are receiving some sunlight, they are going to continue generating power. On a typical cloudy day (overcast), solar panel power output may be lower, but there may still be a significant production of power generated. The exact amount of power generated depends upon the nature of overcast, and can vary considerably. It has been experienced, that on a typical cloudy day, the total energy generation is still around 20 to 30% of what could have been generated on a clear day. Additionally, solar panels perform better at lower module temperature, which is also a case on a cloudy day.The best example of use of solar panels in cloudy weather is in countries located in Northern and Central Europe, like Germany and UK, who lead the total Solar PV installed capacity tally with 40+ GWp and 12+ GWp capacity respectively.
One cloudy day isn’t significant compared to the amount of sunshine over a full year
Most of the Indian cities get around 300 or more sunny days in a year. Even during the monsoons, pitch dark cloudy days are usually limited to coastal or hilly regions of the country. Moreover, with Net Metering arrangement, the user can get benefit of excess production during Summer (and clear) months, to be used during Monsoons (and cloudy) when solar production is less.
Paying attention during System Design
While it is expected that Solar PV Plant output is less during cloudy days, one can still design the system to maximise the conversion of whatever little amount of sunlight available. There are solar panels available in market, with better low light performance. Meaning, their conversion efficiency is still significant in low light conditions. Additionally, during system design, the attention needs to be given to string sizing and inverter selection, to allow functioning of plant even when lesser DC power is available.
The most useful factor to account for profitability of solar plant is the average annual production, and not the ups and downs in daily production seen due to change in weather. Further, the net metering arrangement allows use of excess generation during summer months, to be utilized when production is less. Additionally, it is important to pay attention during design of the solar PV plant, and hence to choose right Solar Installation Company with right technical know-how.