It's 6pm and you've just put the dinner on to cook when, suddenly, the lights dim and your bubbling pans slow to a sluggish simmer. Welcome to the reality of electricity brownouts. Major dips in electricity supply are common for millions of people around the world, especially at times of peak demand. But now scientists have come up with a smart way for some communities to avoid this problem, known as the 'GridShare'.

Around 50 million households worldwide are thought to rely on renewable energy mini-grids. For many people these systems have transformed their lives, bringing electricity to remote and rural areas. But renewable energy mini-grids also tend to suffer from brownouts during peak demand. During a brownout, lights dim, televisions flicker and electrical appliances such as rice cookers may not function properly.

Karma Dorji, a graduate student at Humboldt State University, US, was only too familiar with the problem in his native Bhutan. Many villages in Bhutan have micro hydroelectric mini-grids and brownouts are common, particularly first thing in the morning when people are heating water and in the early evening when people are cooking rice. After being introduced to the problem by Dorji, a student group from Humboldt State University designed a device that encourages residents to cook at different times, thereby spreading the load more evenly and avoiding spikes in demand.

To do this, the GridShare gives users feedback about the state of the electricity system. It works by having a device installed at the electricity entrance point in every house on the mini-grid, along with an LED indicator box located indoors, usually near to the household's high-power electrical devices. The system measures the voltage and current entering each home, while the LED lights provide the user with information about the status of the power grid: green for normal, red for brownout.

"The GridShare is smart enough to recognize if people have started cooking before the brownout," explains Arne Jacobson of Humboldt State University, who was the adviser for the project. "In such a case, it gives them a one-hour grace period to allow them to finish cooking."

A pilot study was carried out in central Bhutan at the Rukubji micro-hydro power plant, which serves the villages of Rukubji, Tsenpokto and Bumiloo. All 90 households were fitted with a GridShare device and electricity use was logged. The data showed that severe brownouts were reduced by over 92% after the GridShare devices were installed. Before the GridShare installation, customers experienced an average of 45 minutes of brownout conditions per day, of which 30 minutes were spent in severe brownout. After installation, the daily average decreased to 8 minutes, of which only one minute was spent in severe brownout. The findings are published in Environmental Research Letters (ERL).

Customer satisfaction with the new device was generally high. "Users found that their rice was more likely to cook properly and many residents thought their rice cooked faster than before," says Meg Harper, a student involved in the project. "Other residents stated that the quality of their lighting had also improved."

As yet, the scheme has not been rolled out further but the scientists hope to work with other villages with similar brownout problems. Ultimately they believe that the GridShare could solve brownout problems in many parts of the world, particularly in South Asia and South East Asia, where mini-grids are common.