Over the past few years, homeowners and building managers up and down the country have been contacting solar panel installers to enquire, ask questions and take their first steps towards a greener, more secure energy future.
There are a wide range of different questions, most of which are debunking myths, explaining common misconceptions and giving a realistic account of the potential savings someone could expect by fitting panels on their roof.
Solar panels are often still generating power even on cloudy or rainy days because they rely on UV light rays that pierce through clouds, with more efficient modern designs being far better at generating power on stormy days than one may expect.
However, a question that is not asked terribly often but is quite fascinating to answer is whether solar panels work during a solar eclipse, where the sun and by extension its UV light is not partially obscured by clouds but blocked completely by the Moon.
There is an answer to this question, and it matters more often than one might expect.
Solar Panels And Solar Eclipses
The focus of the question here is solar eclipses. Lunar eclipses, where the moon enters the earth’s shadow and appears a copper colour, do not matter from the perspective of solar panels because they, by definition, only occur at night, when solar panels are not generating power.
Instead, a solar eclipse, which occurs somewhere on Earth once every 18 months, is a far more fascinating question, as there is a noticeable and dramatic effect on panel efficiency during the eclipse itself, although the extent to which this causes issues largely depends on the type of solar eclipse.
Whilst solar eclipses happen every year and a half, they are often localised to a relatively small part of the world. Whilst many countries will notice some effect, usually in the form of a slightly dimmer sun, people in the wake of a total eclipse will see night suddenly appear, a ring of solar fire the only light in the sky.
Partial solar eclipses reduce the amount of energy generated by solar panels by the amount of light obscured by the eclipse.
For example, the next solar eclipse visible to the UK is on 29th March 2025 and is set to cause between 30 per cent and 42 per cent obscuration of the sun.
During that time, energy generation will drop by that amount, but in the case of a total eclipse, it would lead to an almost complete halt in energy generation. A 2017 eclipse in Texas reduced energy grid generation from 99.2 per cent to just 7.6 per cent.
However, whilst these drops are dramatic, there are plenty of reasons not to be worried.
The next total eclipse of the United Kingdom is not expected until 23rd September 2090, a mere 66 years away. This means that in practice concerns about eclipses are irrelevant for many homeowners today.
The second, and more important point is that eclipses are not total for very long, lasting for typically four minutes before the obscuration starts to lift, although generation will remain affected for a few hours.
