Average Peak Sun Hours (United Kingdom)

CitiesAverage Daily Peak Sun Hours (kWh/m2)
Kingston Upon Hull2.5
New Castle Upon Tyne2.5

What Are Peak Sun Hours?

A peak sun hour equates to 1 hour in which the sun’s solar irradiance (sunlight) produces an average of 1000W (energy) per square meter (roughly 10.5 feet). In other words: 1 peak sun hour = 1000 W/m² of sunlight per hour.

We feel it’s also important to note the difference between DNI, DFI and GHI:

  • GHI (Global Horizontal Irradiation) – This is the sum of both diffuse and direct components reaching the same surface.
  • DNI (Direct Normal Irradiation) – This is the part of solar irradiance that directly reaches a surface.
  • DIF (Diffuse Horizontal Irradiation) – This is the part of solar irradiance that is scattered by the atmosphere.

Many people make the mistake of utilizing DNI data to size their solar system, when in actual fact they should be using GHI. For a complete glossary of all the solar terms we use, be sure to check out NREL.

How Many Hours of Sunlight Does The United Kingdom Get?

Compared to sub-Saharan Africa, the United Kingdom experiences lesser amounts of solar irradiation. On average, the country sees between 730 – 1095 kWh/m2 a year. Simplified, this translates to 2.0 – 3.0 peak sun hours a day, with the  seeing the lower end of that spectrum and seeing the higher end.

How To Use Our peak Sun Hours Data?

Although not as significant as other countries, peak sun hours do vary somewhat depending on where you actually live in the United Kingdom. For example, if you stay in London, you can expect 2.8 peak sunlight hours every day.

In order to know what size solar system your home will need, you can use the following formula: Monthly electric usage ÷ by monthly peak sun hours, X 1000. If you want to know how many solar panels you’ll need, simply divide that amount by the power rating of your desired solar panel.

Here is a written example: You live in London and your monthly electricity consumption is 500kWh. Your areas monthly peak sun hours are 87 (2.8 x 31 days) and you want to install a in your system.

(500kWh ÷ 87)  x 1000 = 5747 watts. You will need a 5.74kW solar system to offset your monthly energy consumption. 5747 watts ÷ 400 watts = `14 panels needed.