The efficiency of solar street lights on cloudy days is usually affected by a variety of factors, including the thickness of the clouds, lighting conditions, and the type of solar panels.

Solar street lights can still collect energy on cloudy days, but the efficiency will be reduced. Solar panels are able to work in lower light conditions, although the light intensity on cloudy days is much lower than on sunny days. Typically, the energy collection efficiency of solar panels on cloudy days may drop to between 20% and 50%, depending on the thickness of the clouds and other environmental factors. Therefore, although energy can be collected on cloudy days, in order to ensure continuous power supply, many solar street lights are equipped with battery storage systems to provide power when the light is insufficient.

Generally speaking, the efficiency of solar panels on cloudy days may drop to between 20% and 50%.

Specifically:

Mildly cloudy: If the clouds are thin, relatively strong scattered light may still be received, and the power generation efficiency may be between 40% and 50%.

Moderately cloudy: The clouds are thicker, the light is significantly weakened, and the power generation efficiency may drop to 20% to 30%.

Severely cloudy days: In very dark conditions, the power generation efficiency may be lower, even close to zero, but some weak light energy can still be collected.

In order to cope with the insufficient power generation on cloudy days, many solar street lights are equipped with battery storage systems to ensure that they can still work normally when there is insufficient light.