Almost every community group and business in Devon and Cornwall could gain access to a hundred-million-pound treasure chest designed to stimulate the region's energy self-sufficiency and cut electricity bills.

Cornish-based charity Community Energy Plus has told the Western Morning News its initial £20 million investment package to place solar panels on south-facing roofs will soon be rolled out to Devon following the pilot scheme's hugely successful launch two months ago.

The project – the largest of its kind in the UK – was created to give hard-up community groups access to a grant which would pay for their solar installations, with the potential to provide sun-powered energy to generate electricity. Five companies who had contributed to the fund would also earn money off the Government's Feed-in Tariff incentive for producing green surplus energy.

But, following a clamour for the cash from Cornish community groups, several powerful investors have come forward to help swell the project coffers. Those behind the scheme have heralded the move, saying the cash has the potential to affect almost every home, community group and business across the two counties.

Neil Farrington, Community Energy Plus's sustainable energy projects manager, said: "When we launched this scheme in July we were thinking about the possibility of branching into Devon.

"But this has really exceeded our expectations. We are really pleased to be able to take this project outside of Cornwall too, and are able to work with businesses as well as community groups.

"This is a very exciting time for us, and everyone involved in the project.

"The money is there to be used so it means, potentially, every south-facing roof suitable for solar PV panels could obtain a grant. This project has a lot of possibilities."

Buildings taking up the offer will be able to take advantage of free electricity generated by the systems ranging in size from 2 kW to 50 kW, but, unlike other "rent a roof" schemes, will also receive an income from any electricity not used within the building that is exported to the National Grid.

With the maximum size of 50kW systems on offer, eligible buildings could save up to £7,000 a year on their electricity bills by using all of the energy as it is generated, or receive an income of up to £2,400 a year for exporting all of the electricity produced to the National Grid.

Since launching their Solar Communities 2011 scheme in July, Community Energy Plus has received interest from almost 150 organisations and technical surveys and planning applications are currently under way on around 100 buildings.

Mr Farrington added: "With uncertainty surrounding the Government's Feed-in Tariff subsidy rates from April 2012, the future of commercial and privately financed schemes cannot be determined.

"We want to ensure that as many local communities as possible take advantage of the feed-in tariff while it exists.

"While we initially focused the scheme on community buildings in Cornwall, the demand and finance available has given us the opportunity to expand the scheme into a wider area and to a more inclusive range of buildings."

The Cornwall-based installers involved in the Solar Communities 2011 scheme include Clean Earth Energy, Plug Into The Sun, Solar Solutions and Solen Energy UK.

Mr Farrington said there were also other investors who were injecting cash into the renewable energy scheme "for ethical reasons".