If you're out and about in Wales or Scotland later this evening, you might notice that rare phenomenon, a solar eclipse! Albeit not a total one - but what impact might such an occurrence have on your solar panel system?
Impact on a Solar PV System
Of course, given its short duration, a solar eclipse will not have a huge impact on the average output of your solar system. Even if you are lucky enough to be in the direct path of a solar eclipse (and this time round that privilege is reserved for our friends on the other side of the Atlantic) your output will only drop dramatically for that short period, which can be as little as seconds, when the sun is totally obscured. At other times when the moon is only partially covering the sun, the radiance will decrease, leading to a decreased output, but only marginally more than a cloudy day, depending on the amount of coverage.
While the total duration of an eclipse can be up to three hours, for most of this time, the radiance from the sun will be diminished but not totally disrupted, as only a part of the sun is obscured by the moon. While this will undoubtedly have an impact on the solar energy you generate over the course of the day, these are such rare events that it’s not really a factor in the system’s generation over the long term. Solar panel systems are designed to work seamlessly with varying light levels, so as the output from your panels drops, grid or battery electricity will kick in to ensure there is no disruption to your energy usage.
Implications for the Wider Grid
While a curiosity for a domestic solar system, on the scale of the national grid, solar eclipses can be a useful way to study a grid resilience in the face of one particular source of power - photovoltaic - dropping for a period. While less of an issue in the UK where only 5-10% of nationwide electricity is produced by solar, much more is produced by wind for instance, nevertheless such an event can test the ability of the grid to withstand a sudden drop in power. For example, battery storage may be used to temporarily plug the gap, in much the same way as it would be used in a domestic system, and it tests the grid’s ability to online other power sources to make up the shortfall.
Conclusion
Overall, a solar eclipse or a partial solar eclipse is a natural spectacle that I hope you’ll agree is worth the drop in power if you have the privilege to witness one. The last total solar eclipse in the UK was in 1999 and covered the south west of the country. The next one on the UK mainland won’t be until 2090. Given the rarity of the event, most solar PV systems will never be impacted by one. So if you’re going to be in the path of the partial solar eclipse later this evening, be sure to drink in the spectacle without worrying too much about your solar panels. With the correct safety measures of course!
