The humble street light is joining the ranks of wind turbines and solar power plants in supplying renewable energy to the electricity grid.

A street lamp covered in photovoltaic cells, which can generate more energy from sunlight than it consumes to light the street, is being tested in the UK. And the lamp is already supplying electricity to the National Grid.

The SunMast, developed by Scotia, based in Aarhus, Denmark, generates electricity from sunlight during the day, which it supplies to the grid. It then simply draws electricity back from the grid at night to power its light.