One of the most common mistakes when making the decision to invest in a photovoltaic installation is to think that it will produce more energy and its performance will be greater the higher the temperatures are. After all, more temperature means more sun, and that’s a good thing, isn’t it?
Here we explain how temperature affects photovoltaic production.
Better in summer or in winter?
Although it is true that the summer months are when most photovoltaic energy is produced, this is mainly due to the fact that this is also the time of year when there are more hours of sunshine throughout the day. And the more sun, the better. This is because photovoltaic cells trap the light from the sun’s rays and not the heat. To understand why, it is necessary to talk about their principle of operation: by means of the so-called photoelectric effect, the sun’s rays activate the materials in the cell, causing them to release electrons, i.e. electricity is produced.
Temperature is therefore not the cause of electricity generation through the photoelectric effect, but it does affect the efficiency of photovoltaic cells: it is inversely proportional to temperature. In other words, the hotter it is, the worse it is!
Conversely, lower temperatures improve the performance of the system. Therefore, despite the shorter days, fewer hours of sunshine and a higher probability of cloudy or foggy days in winter, the cold weather at this time of the year is beneficial for PV production.
How does rain affect photovoltaic production?
Even if it is cloudy or raining, photovoltaic energy is still produced, albeit to a lesser extent. This is due to the fact that, although the sun is not visible and therefore there is no direct solar radiation, there is diffuse solar radiation, which is captured by the photovoltaic cells to continue producing in these cases.
In addition, rain has an extra beneficial effect, because when the panels are installed at the right inclination, the droplets run off the surface and contribute to cleaning the surface, removing accumulated dust and thus improving the performance of the panels.
What if it snows?
We have already talked about PV panels being more efficient in cold temperatures, but what happens if it snows?
If it snows lightly, there is no problem. The PV system is able to continue to produce even in snow, although, as was the case on rainy days, to a lesser extent. Typically, the very slope of the panels prevents excessive accumulation of snow on their surface, and the reflective glass causes the accumulated snow to melt faster.
On the positive side, the white colour of the snow causes what is known as the albedo effect, i.e. the sun’s rays reflect off the snowy surface and cause a greater amount of diffuse radiation.
During heavy snowfalls, we will have to make sure that the snow does not completely cover the surface of the photovoltaic panels.
In short, the cost-effectiveness of a PV system does not depend on the time of year. If you live in a cold place with few daylight hours or frequent snowfalls in winter, the benefit of installing PV panels can still be seen in the long term. However, it is necessary to study each individual case in order to install the right number of panels and the right orientation and inclination.