A UK energy company is trialling giving electricity away free to customers at certain times as a way of tackling the problem of how to store renewable energy when demand is low.

Octopus Energy Group's plan is a response to the problem of curtailment, when more solar and wind energy is produced than can be loaded onto the power grid.

Curtailment can lead to renewable energy production being switched off, even during sunny and windy conditions, until demand returns.

Research is emerging into the costs of curtailment, with renewable power generator Drax Group estimating that wind curtailment in the UK in 2020 and 2021 effectively cost consumers more than £800m ($1.03bn).

As large-scale storage solutions are still being developed and rolled out for intermittent sources of power like sun and wind, evening out demand can be another way to keep renewable energy flowing.

Octopus says customers – initially some households in the south and east of England – will be helping the grid "become greener, cheaper and more resilient".

Electricity will be free when there is "excess" electricity on the local grid from renewables, and the company plans to tell consumers the timings a day ahead.

"We no longer need to switch off bountiful solar and wind power when consumers can use it up for free instead. It is good for the grid and good for the planet," said Alex Schoch, head of flexibility at Octopus.