How has the weather been affecting solar generation in Northern Ireland?

In Northern Ireland we sometimes joke about experiencing all four seasons in one day. The changeable weather we experience is due to being located on an island in the Atlantic Ocean, far above the equator. The hottest month in Northern Ireland is typically July, with average temperatures ranging between 17.5°C in upland areas, and 20°C in low lying areas. Summer 2018 was one of the hottest year’s on record, with temperatures reaching 30°C. 

The most important factor for determining solar panel performance is availability and intensity of sunlight radiation. Solar radiation reaches the earth in wavelengths and the amount reaching the earth is determined by continuously changing atmospheric conditions, including cloudy skies and the position of the sun. 

Solar panels, like most electrical equipment, function more effectively in cooler conditions - when the surface temperature of solar photovoltaic (PV) panels reaches 65°C the solar-cell efficiency can start to reduce. The maximum efficiency for solar collectors is achieved when the temperature is between 15°C and 35°C, so last summer solar collectors will have benefitted from the long sunshine hours we experienced. 

Northern Ireland receives around 60% of the solar radiation found at the equator when conditions are clear and bright.  

Cloud cover absorbs some of this radiation, reducing the capacity reaching earth - this is called diffuse radiation. Northern Ireland is generally cloudier than many of its neighbouring countries because of its proximity to the Atlantic and its hilly terrain. Nevertheless, in the winter months, our weather remains changeable, solar panels will generate electricity when the skies are clear or cloud cover is scattered and thin.  

So although our winters can be cold and dark, solar panels will still generate as their output is usually only affected by the shorter days. From October to March a solar panel can still achieve 25% of its annual output.  

You can read more about PV systems on the domestic solar page on our website which includes some useful information relating to payment and metering FAQs.