The quantity challenge for solar

Solar power is a renewable and almost inexhaustible energy source – but how much energy can be harnessed to generate electricity is limited by current technology and the UK climate.

The challenge

It is thought that the UK could theoretically generate up to 1080 billion kilowatt-hours per year (kWh/year) from solar power if 5% of the UK were covered by 10% efficient panels. The UK is located at a relatively high latitude – generally less sunny and where the sun is not as high in the sky as it is closer to the equator. London receives an average 0.11 kilowatts of sunshine per square metre (kW/m2), compared with 0.19kW/m2 in Athens, and 0.24kW/m2 in Cairo. 

Solar panel efficiency

A solar panel's conversion efficiency is how much of the solar energy striking the panel it can convert into electricity. Most solar panels on UK homes are photovoltaic (PV) cells, which typically have a conversion efficiency of 15%.

To meet average UK peak electricity demand of 60 million kilowatts (kW) from solar power alone, a huge area many times the size of Greater London would have to be covered with solar panels. And even such a vast and impractical installation such as this would still need back-up from other energy sources – at night, during winter and on cloudy days.

The solution

Solar energy will not run out any time soon: it is estimated the sun will continue to shine on us for at least another 5 billion years.

Improving the efficiency of solar photovoltaic (PV) panels would enable the UK to harness a greater proportion of our solar energy resource. But even with such improvements, our climate means solar energy is unlikely to make a major contribution to bridging the potential UK energy gap.

More efficient solar panels

Typical solar PV panels can convert around 15% of the solar energy that strikes them into electricity. There is development work being done to try and dramatically increase the efficiency of solar panels. If this is successful then solar power would become a more attractive option, particularly in countries with relatively little sunlight such as the UK.

Increasing the number of solar panels deployed in the UK will obviously increase the amount of electricity we can generate from sunlight. But because of our climatic limitations, solar is regarded as microgeneration technology and not suitable for large-scale generation.

Feed-in Tariffs

The Feed-in Tariffs (FiTs) scheme is helping to increase the number of PV panels being installed in the UK. In the first year after launch in 2010, more than 21,000 renewable installations were registered, including solar power schemes.