Solar farms could soon play a vital role in the energy system 24 hours a day, after a breakthrough trial proved they can even help balance the grid at night. National Grid used a solar farm in East Sussex to help smooth overnight voltage fluctuations for the first time earlier this month, proving solar farms don’t need sunshine to help keep the lights on.

Lightsource BP, the owner of the solar farm, said an inexpensive tweak to the project’s electrical equipment meant it could help balance the grid with only two seconds’ notice. Kareen Boutonnat, the company’s chief operating officer, said: “We have proven that solar plants can play a larger role across the electricity network. But this is only the beginning.”

The breakthrough could mean that UK solar farms will soon help stabilise the energy grid at night, which could save £400m on grid upgrades or building new power plants. “Inverters” at the solar farm are usually used in the process of converting solar energy to electric current. But at night, when the grid is often less stable, the same equipment can adapt grid electricity to a healthier voltage.

Chris Buckland, technical director of Lightsource BP, said the inverter acts like a distortion mirror by reflecting the energy network’s voltage back to the grid at a slightly different level.

On blustery nights with plenty of wind power but little demand, the solar farm could help prevent the energy grid’s voltage from rising too high. It could also prevent the voltage from falling too low during still nights in winter when demand is often high.

Lightsource BP will carry out a second trial next month, and it hopes to strike its first commercial deal to help balance the electricity grid with National Grid next year.