Solar panels installed on the roof of the Town Hall in Wembley last year have generated enough energy to power three family homes for a year.
The panels have saved the council almost four tonnes of carbon and on a sunny summers' day can generate enough energy to power 100 computers or 600 low-energy lights.
The Solar Photovoltaic panels producing electricity were installed early in 2008. Since then they have produced 6,900 kw of electricity the equivalent to around the electrical energy use in three family homes, providing about 0.5 per cent of the electricity used at the Town Hall, saving the council £700 per year in energy costs.
The electricity is all utilised within the main building and no electricity is exported to the grid.
They have also saved 3.9 tonnes of carbon dioxide.
A display panel installed at the entrance of the building shows how much energy is being generated at any one time and how much CO2 is being saved.
Richard Barrett, Head of Property and Asset Management at Brent Council, said: "The Solar panels have been a brilliant success. Already in their first year we have saved enough electricity to power three family homes. With the promise of a summer heat wave it will be interesting to see how much is produced this year."