The largest solar panel array in the Channel Islands has come online on the roof of the Guernsey Post headquarters.
The energy generated by the array's 654 panels is expected to exceed 200,000 kW/h per year.
This would exceed the annual amount of electricity required to power the post office's fleet of 82 electric vans.
The project was completed in partnership with Guernsey Electricity, which will use the energy generated by the panels in the island's power grid.
Chief executive of Guernsey Electricity Alan Bates said the panels were a key part of the company's attempt to develop "community based" sources of renewable energy to go into the island's power grid.
The panels have been projected to reduce the Guernsey Post's carbon emissions by about 150 tonnes a year.
They represent the second phase in the States-owned firm's shift towards becoming a carbon neutral organisation, after switching to electric vans in 2018.
The company's chief executive Boley Smillie described the installation as the "icing on the cake" of the efforts to reduce the company's emissions.
He said the switch to electric vehicles had already delivered "significant cost savings".
"As a business we're constantly looking how we can improve our environmental impact, whether that's waste reduction or this project," Mr Smilie said.
In November, Guernsey's grid is due to return to be being linked to the French grid by a new undersea cable laid earlier in October.
The island has been forced to rely on generating its own energy by burning fossil fuels for a year since the last cable was damaged.
The planned reconnection would return the island to having up to 90% of its energy supplied by renewable and nuclear sources.