What is community owned solar on a large-roof?

Unlike a solar farm, installing community solar on an existing roof in your community provides your project with its first customer and energy user. This makes a big difference to the economics of your project.

What does it mean to set up solar on a large-roof?

You will need to identify a good site for solar. Ideally the site has high electricity bills and the project will easily be able to generate savings.

Commercial and industrial buildings, community buildings and sheds can all have large rooves for a community solar project. The size of the roof, the proportion of solar energy you can sell to the site owner and the arrangement they make with the site's electricity retailer for the surplus solar will help you size your solar array. Solar credits are paid up front as a rebate if the system size is under 100kW, and a system of that size would need 500 square metres of roofspace.

The arrangement between the site owner and the community can vary. Usually benefits are shared between the site owner and the community as the solar owner.

The flow of benefits to the community can also vary. Some community energy groups develop a legal investment vehicle so that community investors can earn a profit. Some groups keep the profits to fund activities and spend on future energy projects. Some community energy groups donate their time to develop the projects, others ensure that the project ultimately repays the group in some way.

Benefits of setting up solar on a large-roof

• Increasing renewable energy: Installing solar on rooves is a common approach amongst community energy groups. Sometimes a solar project only proceeds because the community energy group offers to own the project and find the capital to invest. Sometimes the community energy group offers independent experience in solar projects that the site owner lacks and this is the key to getting a project off the ground.

• Utilising available space: Large roofs provide ample surface area for installing solar, maximising the solar potential of the area.

• Cost savings: Community organisations who participate in these projects can benefit from reduced electricity costs. The shared investment and bulk purchasing of panels and equipment saves money and makes renewable energy more accessible. The host sites can also see lower electricity costs, depending on how the community negotiates to share benefits.

• Energy resiliency: Community solar can reduce reliance on external power sources. When combined with a battery, these systems can be designed to provide backup energy supply during grid outages or emergencies.

Some challenges of setting up solar on a large-roof

• Structural considerations: Careful roof inspections are needed. Structural integrity and load-bearing capacity must be evaluated to avoid any safety risks.

• Older electrical wiring: Some projects have incurred additional costs when wiring, switchboards or connections to the grid have needed upgrading before the system can be installed.

• Complex logistics: Engaging and motivating community members to participate in the project can be a challenge, as well as fundraising to cover the cost. Coordinating the practical side of things such as the install and connection, including logistics like equipment delivery, site access, and installation timelines can be a full time job.

• Ownership and governance: Establishing ownership structures and governance models can be complex. Decisions on ownership shares, revenue distribution, and decision-making processes require careful planning and community consensus.

• Maintenance and monitoring: This is essential for optimal performance of the solar system. Developing a maintenance plan and ensuring ongoing monitoring can be challenging, especially when involving multiple stakeholders in a community setting.

• Relationship with the site owner: The relationship with the site owner will involve legal arrangements for the use of the roof and the sale of the electricity. The energy user may need to change tariffs with their retailer to get the best arrangement for the two sources of energy - the main grid and the solar system. A simpler arrangement is to provide the investment for the solar panels and let the site owner retain ownership.

When is setting up solar on a large-roof a good choice?

• A community solar system makes sense when there is a community desire to add more renewables in their town and increase resiliency.

• There needs to be a large local roof space that can host such a system.

• The host site needs to be able to consume as much of the solar generation as possible to present a viable business case so that investors or the community energy group get a good return on their investment.

• Community solar on a large roof works well when there is a strong sense of community collaboration and empowerment, and possibly a longer term goal to build energy self-sufficiency.

Project examples for community solar on a large-roof

Repower Shoalhaven: Repower Shoalhaven developed one of the first community owned roofop projects on its Bowls Club.

COREM: COREM in Mullumbimby uses a revolving fund to deliver rooftop solar and return benefits to the community.

Pingala - Young Henrys: Pingala, in Sydney, uses a cooperative model to match investors and projects.

Other guides and resources

Small-scale community solar guide: This guide provides 10 different examples of community solar alongside the legal and business models of each. It will help you understand the key issues to be agreed at the outset of a project.

Community-owned renewable energy - A how to guide: This guide takes you through the steps of developing a community energy project.

See also our explainer on your different options for solar in your community.