Wednesday's eclipse will temporarily wipe out a significant portion of the nation's solar output
Thousands of households could receive free electricity next weekend by cutting their power use for just two hours.
Customers will also have the chance to win fully installed solar panels or a £12,000 cash alternative as Britain prepares for its deepest solar eclipse since 1999.
Octopus Energy, the country's largest energy supplier, is asking customers to reduce their electricity use between 6pm and 8pm on Wednesday, August 12.
During the eclipse, the Moon will obscure up to 95 per cent of the Sun over parts of Britain.
Customers who successfully lower their usage during the two-hour window will be rewarded with free electricity the following weekend through the company's Eclipse Power Down initiative.
Those taking part can also enter a photo competition for the chance to win solar panels fully installed at their home. The winner can choose to receive a £12,000 cash alternative instead.
Wednesday's eclipse will temporarily wipe out a significant portion of the nation's solar output precisely when millions of people are arriving home and switching on appliances.
The eclipse is the most significant to darken British skies in nearly three decades, with nothing comparable expected again for decades.
Solar power has become an increasingly vital component of Britain's energy mix.
Last month it accounted for a record 14.4 per cent of the country's total electricity generation, meaning even a brief loss of sunshine creates a notable shortfall that must be compensated for.
Without intervention, that gap would likely be plugged by firing up additional gas-fired power stations.
However, if sufficient numbers of households postpone energy-intensive tasks for a short period, that extra fossil fuel generation can be avoided.
The eclipse photo competition offers a particularly enticing prize: a complete set of solar panels fitted to the winner's property at no cost, with £12,000 in cash available as an alternative for those who prefer it.
Participating in the power-down scheme itself requires minimal effort.
Octopus suggests customers simply reschedule routine domestic chores to fall outside the 6pm to 8pm slot — running the washing machine earlier in the afternoon, for instance, or holding off on the dishwasher and games console until later in the evening.
The approach reflects a broader principle: that small adjustments by large numbers of households can collectively make a meaningful difference to how Britain's electricity grid copes during moments of unusual strain.
Rebecca Dibb-Simkin, Chief Customer Officer at Octopus Energy, said: "Many of us will be looking up at the sky on Wednesday evening to experience this once-in-a-generation event. But as the Sun disappears, so will some of Britain's solar generation, just as demand peaks.
"By shifting everyday tasks like the washing machine or dishwasher until later, households can help reduce the need for gas power stations - and earn rewards for doing their bit."
The Eclipse Power Down forms part of the Octoplus rewards programme, which now has more than two million members.
To date, the scheme has distributed over £11million in rewards and supplied 20.5GWh of complimentary electricity to participating households.
Octopus estimates that British homes could unlock as much as 13GW of flexible capacity through smart appliances, electric vehicles and home batteries, though only a small fraction of that potential is currently being tapped.
