Solar Panels and Overcast Days

There is a general misconception that solar panels, used to generate electricity and energy from the sun, do not work on overcast or cloudy days. This continues into the belief that solar panels are only useful during the summer months, rendering this form of renewable energy somewhat useless for half of the year during winter.

It is easy to understand where these misconceptions come from. Solar panels need solar light (and it is assumed, heat) to function; without sun rays hitting the panels, it would make sense that no energy could be produced.

However, there is a difference in what we consider to be the sun’s power and what is the actual power of the sun. We as humans associate solar rays with strong, yellow sunshine in a cloudless sky; the kind of weather conditions that have you reaching for a hat and for sunblock. While solar panels will flourish in these conditions, just because the sky is overcast or the temperature is low does not mean solar panels will cease to function.

This is because the sun is always casting rays down on earth, even if there is cloud cover interrupting its route to the surface of our planet. Many people each year, much to their surprise, find themselves suffering sunburn on what appeared to be a cloudy and overcast day. This is because the sunlight is still getting through, but it is just more filtered and obstructed than usual.

For solar energy, the important part of the above sentence is that the sun is still getting through. Even when we would consider the sun not to be shining, it is – unless it is night time! Solar panels are therefore able to function in most weather conditions, albeit with reduced output.

Did Solar Panels Work In Winter?

When solar energy is touted as one of the natural replacements for the consumable energies of coal and oil, one of the first questions that is always asked is: what will happen in winter? Can solar panels function when there is precious little sunlight?

The simple answer is, yes. Even in winter, most countries experience six to seven hours of daylight, and to an extent this is all a solar panel needs to function. Solar panels, despite the name, do not necessarily need direct, hot sunlight to produce electricity; but what they do need is light. In daytime, some of the sun’s rays are getting through to earth even when it is cold and overcast. Quite simply, if these rays weren’t getting through the cloud cover, it would not appear to be daytime!

Therefore, for as long as it is daytime, solar panels can function and produce electricity to a degree. Temperature is a relatively unimportant consideration in solar panel development; in fact, some experiments have shown that the mechanisms and generation systems of solar panels actually function better when it is colder. All electrical systems slow down somewhat in intense heat – such as trying to use a laptop on a hot day – and the crisper temperatures of winter can allow solar panels to work to their full potential.

While all of the above it is true, it is nevertheless also a fact that the output of solar panels is effected by a lack of daylight – something which is characteristic with winter. One would not get the same effective output on a winter’s day as one would on a summer’s day, and for this reason other energy generation sources are required for the winter months. Thankfully, in most countries winter may decrease the amount of solar output, but the weather changes in a way that is beneficial to other renewable energies – such as tidal or wind power, which may be less effective in the more temperate summer months.

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