Resonance backs volunteer-led rooftop solar developer  | Impact Investor (2025)

Big Solar Co-op hopes to install 100 megawatts of solar capacity on the roofs of commercial and community buildings by 2030.

A social impact fund run by UK-based Resonance is providing £800,000 (€937,000) of funding to non-profitBig Solar Co-op, as the drive to boost the country’s under-developed solar energy market intensifies.

The investment byResonance Community Developers(RCD) is aimed at allowing Big Solar Co-op to expand its solar project portfolio, as it chases a target of installing 100 megawatts (MW) of solar panel capacity on or near commercial and community buildings by 2030.

Volunteer-led Big Solar Co-op’s operating model means installations are co-owned by its membership on a non-profit basis. It currently has over 650 members.

The organisation has installed around 1.2MW of capacity to date and has made around 10 installations in the last two years, the largest of which was a 593-kilowatt project with more than 1,500 panels on a packing plant.

RCD said that, with the Big Solar Co-op investment, it has now committed around £10macross some 30 community groups across 10 English regions. Earlier in April, the fundreceived a £20m (€24m) commitment from the UK government. It mainly invests in projects seeking to develop affordable homes, sports and leisure facilities, clean energy generation and other assets, such as community pubs.

Jon Hallè, Big Solar Co-op’s CEO said Resonance’s loan, combined with other sources of finance, would enable the non-profit to build new solar installations at the rate of one per month in the first half of 2025 on the rooftops of buildings such as schools,leisure facilities, factories and supermarkets, across the UK.

Big Solar’s existing installed capacity “will generate enough electricity to reduce UK carbon emissions by around 350 tonnes a year– that’s enough energy to drive an electric car over 2 million miles”, he said.

The non-profit told Impact Investor it was on course to add over 5 MW this year, with further expansion to be partly fuelled by rooftop solar, including 30 sites for a supermarket chain. The organisation is also building ground mount solar where there are suitable sites, including a 3.52 MW site to be built this summer.

UK renewables drive

Although the scale of Big Solar Co-op’s activities is relatively small, it is part of a widerdrive to build the contribution of solar power in the UK’s energy mix in pursuit of a current government target to reach net-zero emissions by 2050.

Just under 5% of UK electricity was generated by solar photovoltaics (PV) from almost 18 gigawatts of total capacity in 2024, but improving panel efficiency and lower costs are making the sector look more attractive to consumers in an era of volatile grid energy prices.Resonance cites data from Business Solar UK indicating that a 50kW system typically could save businesses over £10,500 annually.

The sector should also get a lift from investment byGreat British Energy, the company recently set up by the UK government to invest in the energy transition. The government originally said it would provide Great British Energy with £8.3bn of taxpayer funding over the current five-year parliament, of which £3.3bn would be set aside for community energy projects, including low-interest loans to local councils for rooftop solar projects.

There are concerns that the cash-strapped government may struggle to meet those funding commitments. But Great Britain Energy hasannouncedthat its first major project will be to provide £200m over coming years to put rooftop solar panels on some 200 schools and 200 healthcare facilities in England, as well as further local clean energy projects in England, and community energy schemes elsewhere in the UK.

Other impact investors are also targeting support towards community energy programmes. In March, Better Society Capital andThrive Renewableslaunched the Community Energy Catalyst joint ventureto mobilise £40m for community-owned wind and solar projects across the country.