Dr Leggett lives in a terrace house in Richmond, Surrey. His gleaming metal-grey tiles were installed three months ago and have generated 337kWh, though he only needs 232kWh. The surplus is sold to Seeboard, the local electricity company.
Dr Leggett, who dubs himself the "chief executive of the Solar Century" (a group campaigning for "green" energy) is delighted to have confounded sceptics who for years have claimed that solar energy is a contradiction in this dark and cloud-covered land.
On sunny days his roof generates enough excess electricity, which he feeds back in to the grid, to cover what he draws out at night and when it's overcast.
In principle, Britain's energy policymakers support solar power. A recent government-sponsored solar taskforce concluded that "Solar PV (photovoltaics) could be the single most important long term means of reducing gas omissions" and one of the most cost-effective alternative energies of the future.
And yet, while the US plans a million solar-tiled homes by 2010, Germany 100,000 by 2005 and Japan 70,000 by 2000, the UK, says Dr Leggett indignantly, has a DTI backed programme for "only 100 and with no firm timescale."
Dr Leggett, a former director of Greenpeace, blames the electricity industry, "No gas, no coal and no nuclear power would be required if every roof was covered with solar tiles. But the power companies have a policy of obstruction.
"The utilities are lobbying the government and regulators as hard as they can to stop the authorities allowing customers to get their due," says Dr Leggett.
Seeboard refutes this and says that it pays him a fair price for the electricity he generates, adding that "Seeboard has no fear of solar-powered generation. Indeed we welcome it and regularly finance research studies into solar and other renewable forms of energy."
To install a 2kW system similar to Dr Leggett's would cost about pounds 20,000. His house needed a new roof (costing up to pounds 7,000) anyway and, while installing the solar tiles, he went for a loft conversion, thereby increasing the value of the property by some pounds 25,000.
The Solar Century has negotiated a "solar mortgage" with a bank to persuade 100 pioneers to have the system installed this year in order to establish a network of national showhomes beyond Richmond.
Dr Leggett is happy to receive visitors to his "house of the future". His enthusiasm is boundless, "on a typical day," he boasts, "my roof creates enough power to make 350 cups of tea, watch 70 episodes of Coronation Street and make 800 slices of toast."
n The Solar Century can be contacted at 0870 735 8100