The first house in Britain with a roof covered entirely with solar tiles is feeding power into the national grid.

The house, at Richmond in south-west London, has been generating electricity since it was commissioned three months ago.

It is the home of Dr Jeremy Leggett, head of Solar Century, a company established to speed the switch to energy from the sun.

Clouds no problem

The imported photo-voltaic silicon roof tiles need light to work, but do not need sunlight.

So even in cloudy Britain, they can produce a useful amount of electricity.

The Richmond house has exceeded all expectations, generating 45% more electricity than Dr Leggett has used.

He sells the surplus to his local electricity company, Seeboard, though it pays him less for his units than it charges him for its own power.

So far the house has generated 337 kWh, while Dr Leggett has used only 232 kWh.

It works - without sunlight

He has sold the extra 105 kWh to Seeboard for four pence per unit. But it charges him between 6 and 8 p per kWh.

The entire generation process is automatic.

Whenever the tiles are producing a surplus, it goes into the grid. Whenever the house needs more power, it takes it from the grid.

Dr Leggett says: "We can now dismiss some of the doubting Thomases".

"Photovoltaic tiles work even in the UK. They do not need planning permission, and they create clean electricity.

"They can provide all the power a household needs and over a period of time they will reduce our bills.

"On a typical day, my roof creates enough power for me to make 350 cups of tea, watch 70 episodes of Coronation Street, or make 800 slices of toast.