Solar Panels Feel the Heat, Too: How Heatwave Temperatures Hamper Solar Power

Days of scorching sunshine are feeding Europe’s grid with record amounts of solar power – but the current heat wave is actually bad news for solar panels.

In Germany, a record amount of electricity was produced by solar energy Sunday, when most of the country was placed under an excessive heat warning.

Even more solar power is expected to be produced in the coming days as Western Europe braces for a heatwave that many countries have never experienced before.

And yet, these record amounts of solar power are a far cry from what the country’s solar panels could have achieved had temperatures been a little lower.

While the increase in energy produced by solar power could be seen as a silver lining to what is likely to be a “killer” heat wave, the heat is actually hampering the solar panels.

Counterintuitively, hotter, sunnier days don’t mean more power, because rising temperatures actually hinder the ability of solar panels to collect power.

How it works?

Solar panels absorb sunlight with their photovoltaic cells, the photons absorbed by the panels removing electrons from their atoms and forming an electrical circuit in the semiconductors of the panel, generating a flow of electricity.

Most solar panels are tested at a temperature of 25 degrees Celsius, an ideal temperature at which this process occurs in solar panels under optimal circumstances.

But above this temperature, regardless of how bright the sun is, the efficiency starts to drop for the panels.

The heat causes an excessive number of electrons in the panel – those responsible for converting the sun’s energy into electricity – to be excited, ultimately reducing the voltage generated by the panel and its efficiency.

The impact is not minimal. High temperatures can reduce the efficiency of solar panels by 10-25%, according to data shared by DEC Greentech.

For every higher degree Celsius reported by a solar panel, its efficiency drops by 0.5 percentage points, according to Solar.com.

Heat wave in Europe

Across Western Europe, temperatures are expected to exceed 40 degrees Celsius.

Unprecedented temperatures are expected in the UK, a country where most homes are not air-conditioned. Across much of southern Europe, firefighters are already battling blazes raging in the heat.

There are obviously also thermal solar panels, which would not be affected by the increase in heat. But these are much rarer panels, especially in homes, and are considered less reliable for generating electricity.

As temperatures continue to rise in the western half of the continent, it is uncertain whether the sunny days ahead will bring record amounts of solar power.

Even though, as people turn to air conditioning for cooling, the demand for electricity increases, renewable solar energy may not be the solution to meet it.