Solar Eclipse 2026: What It Means for Your UK Solar Panels

A deep partial solar eclipse crosses the UK this evening, 12 August 2026, and if you own solar panels you have probably wondered what it will do to your generation. The short version: the eclipse is real and visually dramatic — up to 90% of the sun disappears behind the moon over London — but because it happens late in the day, when the sun is already low and contributing little to your day's total generation, the effect on your actual output is small. Here is what is happening, when, and whether you need to do anything about it.

When and how much of the sun will be blocked

The eclipse is a partial event for the UK, not a total one. According to the Royal Observatory Greenwich, the moon begins crossing the sun over London at around 6:17pm BST, reaches maximum coverage of roughly 90% at 7:12pm, and the event ends around 8:06pm as the sun sets. Coverage increases the further southwest you are: viewers in Cornwall see around 95% of the sun obscured, and observers in the far southwest of Ireland get close to 97.5%. Only the far north Atlantic — Greenland, Iceland and northern Spain — sees a full total eclipse; everywhere in the UK is a deep partial.

Because the eclipse tracks across the sky as the sun is setting, you will need a clear view of the western horizon to see the whole thing, and the sun and moon get progressively lower as the eclipse progresses.

How much will your solar output actually drop

Far less than the 90% coverage figure suggests. Solar forecasting firm Solcast models the UK losing around 1,320 megawatt-hours of solar generation during the eclipse window, with a peak ramp rate — the speed generation swings as the moon passes — of about 4,530 megawatts per hour as output recovers. Set against the country's total solar generation, Solcast estimates that only around 1% of the UK's daily solar irradiance is lost to the eclipse, because it lands in the early evening when the sun is already low in the sky and would be producing relatively little anyway. Germany, where the eclipse happens earlier relative to peak sun, loses a larger share of its daily output by comparison.

For your own system's output, think of it as roughly equivalent to a heavily overcast hour passing through on an otherwise clear evening — noticeable if you are watching your generation app in real time, but not something that will show up in your monthly totals.

How the grid is handling the dip

Grid operators across Europe have been planning for this for weeks. Under the pan-European transmission body ENTSO-E's modelling, total European solar output could fall by up to 9.7 gigawatts under clear skies during the eclipse. Spain's Red Eléctrica expects a national drop of up to 5 GW and has increased its operating reserves; Portugal's REN is prepared to draw on hydro and thermal reserves to cover a forecast loss equivalent to nearly half its average solar output during the eclipse window. In Great Britain, the interconnected nature of the grid means gas, nuclear, hydro and imports from Europe are on standby to smooth out the ramp, exactly as they do for any rapid change in cloud cover or wind.

One UK-specific twist: Octopus Energy is running an “eclipse power-down” event, rewarding customers who cut their electricity use below their normal baseline during the eclipse window with an hour of free electricity (capped at 16 kWh), applied as a later Sunday reward. It is the same demand-response logic behind Octopus's regular Saving Sessions — reducing demand when renewable output dips means the grid needs to call on less gas-fired backup.

Do you need to do anything with your panels, inverter or battery?

No — for the vast majority of home systems, this is a non-event operationally. Your inverter will simply track the changing light level in real time, the same way it does for a passing cloud, and resume normal output as the eclipse clears. If you have a home battery, it will not notice anything unusual; the dip is far smaller and slower than the swings a battery system is designed to smooth out day to day. There is no need to switch off panels, inverters or batteries, and no safety reason to avoid checking your system during the eclipse.

If you want to actually see the effect, open your monitoring app around 7pm and watch generation taper off and recover over the roughly 90-minute window — it is one of the more visible real-world demonstrations of how directly solar output tracks available sunlight. If you were planning to charge an EV or run a battery top-up from solar this evening, it is worth scheduling around the dip rather than through it, though for most households the loss of an hour or so of low-angle evening sun makes little practical difference either way.