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How does temperature influence the performance of a solar panel?

Today we bring you an article about  how temperature influences the performance of a solar panel , and it is that many people think that the maximum performance of a  solar panel  is achieved in the middle of a heat wave, on the hottest day or on the month that we have more temperature.

The maximum performance of a solar panel is NOT achieved when it is hotter

This myth, that the hotter it is, the better a solar panel performs or produces, is totally wrong since the point of maximum performance of a  solar panel  is when the environment is warmer.

Like all conductive or electricity-producing devices, heat negatively affects solar panels, decreasing their performance. 

What happens is that  this negative effect of heat on the performance of solar panels is more than compensated by the increase in solar hours in summer . That is, in summer the solar panel has less instantaneous efficiency, but throughout the day the solar production is greater than in winter days.

Influence of temperature on the performance of a solar panel: practical case with monitoring

In the following video on  our YouTube channel  you can see a real case with the motorization of a photovoltaic installation of how heat affects the performance or efficiency of solar panels:

What is the peak power of a solar panel?

The peak power of a solar panel, for example 265 Wp, is given for the moment in which the sun produces 1000W in 1m2 at 25º (concept called Peak Solar Hour).

There and only there is when  100% performance of these photovoltaic cells is obtained. That is why, we will only see 100% of the production of our solar field develop on sunny winter days, that is, if we install 100 Kwp in solar panels, it will normally be that peak production is reached only on sunny winter days. . 

With the heat, as we say, production decreases. According to most manufacturers, at 40ºC the performance of the solar panel is usually around 80%, so if in summer your  solar installation  has 10kW mounted on panels, it will be producing 8kW at its best.

For this reason, photovoltaic solar energy professionals, when we talk about solar production, we do so referring to full days.

For example, when we talk about a solar self-consumption installation, we give the production data for a full day, in this way we can ensure production taking into account climatic and temperature values.

Solar  modules  are nowadays so optimized that the manufacturer risks giving between 10-15 years of guarantee with a production of 90% and about 25 years of guarantee with a production of 85%, in addition to about 10 years in materials.

How do we calculate the production loss of a solar panel due to heat?

Let’s take an example of the production of a solar panel in one of the hottest months, such as July and in the Cáceres area.

The formula to calculate the temperature increase in a photovoltaic cell with respect to ambient temperature is as follows:

Atº = 0.034 x I – 4 (I being the power in w/m2 produced by the sun)

So in Cáceres in the month of July at about 32ºC the sun would be producing about 772 w/m2, so our temperature increase would be as follows (we obtain these data from meteorological databases):

Atº = 0.034 x 772 – 4 = 22.25ºC

Adding the ambient temperature at the time of analysis we would have: 22.25 + 32 = 54.25 ºC would reach the photovoltaic cell.

So if the manufacturer says that the power of the panel drops by -0.44%/ºC once it exceeds 25ºC, we would obtain.

-0.44 x (54.25 – 25) = -12.87%

Then if the solar panel is 260wp, it would have a power for those conditions of:

100 – 12.87 = 87.13

260 × 0,8713 = 226,54wp

And so after these simple steps you will be able to obtain the real power that your solar panel would be producing for a given moment.

All serious manufacturers of solar modules will provide you with the Temperature Coefficient, data related to the loss of efficiency due to radiation and temperature.

We invite you to take a look at our section on  solar panels  and see their technical sheets and how these coefficients can vary between the different modules. 

It should be noted that  Cambio Energético  installs your solar panels throughout Spain thanks to its network of installers nationwide, in addition to the fact that we currently have the possibility of  financing your installation of solar panels  in 36 months without interest.