Solar panel yield per month

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Average solar panel yield per month

To give you an idea of what panels produce in a month, we have worked through an example. Bear in mind that the yield varies with the type of panel and with where it is installed.

In this example we assume one panel is rated at 440 Wp on average. With 10 panels of 440 Wp each you have 10 x 440 = 4,400 Wp installed.

The weather in the Netherlands is not always sunny, so panels do not produce electricity at their peak rating all the time. When working out the yield we therefore use a factor of 85%, which means about 0.85 kWh of electricity per 1 Wp. For 10 panels the annual yield comes to 0.85 x 4,400 = 3,740 kWh, which works out at an average of 312 kWh a month.

Why the yield differs from month to month

At an average of 312 kWh a month, 10 panels give a steady supply, and most of all during the summer when the yield peaks. But why does it vary from month to month? Several things shape it. In the Netherlands four matter most: temperature, the position of the sun, hours of sunshine and cloud cover. Each of them has a real effect on how much energy panels produce.

Temperature: lower temperatures suit solar panels, because they work more efficiently when cool. Panels perform best between 20 and 25 degrees.

The position of the sun: the angle at which sunlight reaches the earth changes with the season. In summer the sun stands higher, which means more direct radiation.

Hours of sunshine: how long the sun shines differs sharply from month to month. More hours means more energy generated.

Cloud cover: cloud reduces the direct sunlight that reaches the panels, which can lower the yield.

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Yield per season

The yield varies a good deal by season, because the factors above differ per season. Here is an overview:

Spring: the days grow longer and the hours of sunshine increase. Temperatures are usually mild, which suits the panels. April and May are often when the yield starts to climb, with May one of the best months thanks to the balance between sunshine and temperature.

Summer: June, July and August give the highest yield, because the days are long and the sun plentiful. Temperatures can be higher, which lowers the efficiency slightly, but the amount of sunlight more than makes up for it.

Autumn: the yield falls again as the days shorten and the sun grows scarcer. Temperatures stay reasonably mild, which helps the efficiency, but the drop in sunlight lowers the total. September can still be a good month, while October and November fall away considerably.

Winter: December, January and February give the lowest yield, because the days are short, the sun stands low and the sky is often cloudy. The low temperatures do suit the efficiency of the panels, but the lack of sunlight is what limits the result.

Which is the best month for solar panels?

May is the best month for solar panels, thanks to an ideal combination of factors. With the most hours of sunshine in the year and a pleasant temperature, panels usually do better than in June or July. That balance between sunshine, radiation and temperature makes May the most favourable month.