Project Summary
The aim of the project was to identify additional income for renewable generators by exploring the ‘complex site’ approach to local electricity supply between renewable generators and consumers.
The project tests the feasibility of the ‘complex site’ approach using projects being developed by Southampton Council and Bath and West Community Energy (BWCE).
Southampton will be installing PV on its corporate properties and supplying excess generation to its nearby properties. BWCE will be developing ground mounted solar and wind projects and selling the power to nearby domestic customers via the grid.
Background
When a complex site is established, the electricity exported by the generators is deemed to be consumed by the local consumers, then the remaining net requirement or excess of electricity, for the group as a whole, is imported from or exported to the grid.
With the end of the Feed in Tariff scheme, renewable energy generators have difficulty in securing Power Purchase Agreements (PPAs) for grid exported electricity at a sufficiently high price to make them financially viable. One solution to this could be to build business models based on local energy supply.
Establishing a ‘complex site’ encompassing one or more generators selling power directly to multiple customers, could be a way for a generator to sell export at a higher price, and for customers to buy at a lower price by cutting out some balancing, transmission and other charges. This has been done already at a small scale, but coming changes to the Balancing and Settlement Code should make this more straightforward. See proposed modification P441 ‘Creation of Complex Site Classes’ – Elexon BSC.
Our Role
The Hub explained the concept of a ‘complex site’ to Southampton Council and recruited them to the project to join with BWCE. The Hub then commissioned Energy Local to undertake the feasibility study.
Location
- A solar farm near Bath, plus another potential site with a combined wind turbine and another solar farm near Bath
- Roof mounted solar on several Southampton Council office buildings
Technology
Southampton Council is using 626kW rooftop solar on its building portfolio.
Bath and West Community Energy is using 1MW ground mounted solar at one site and a 1MW wind turbine co-located with 1MW ground mounted solar at another site. These are commercially viable options for the locations with the potential for a successful planning application.
The total generation is 4.55GWh/yr
Financing and Ownership
Southampton plans to fund its installations with borrowing from the Public Works Loan Board. BWCE will likely fund its projects by means of a share issue, debt and grants.
Results
The study identified two areas of Southampton containing several council properties where a the ‘complex site’ approach would benefit the council by enabling it to sell exported rooftop solar generation from property to property, reducing its energy bills and improving the financial viability of installing PV.
For BWCE, combining a solar farm with a wind turbine produces a better generation profile than solar alone and so it would be worthwhile setting up a ‘complex site’ to sell power to local domestic customers.
Lessons learnt
Whether establishing a ‘complex site’ will help the economics of a project is quite site-specific depending on the generation profile of the generator and the number of customers.
Benefits
The benefits of setting up a ‘complex site’ around a renewable generator are increased income for the generator and reduced energy bills for the consumers. It also helps the electricity supplier by reducing its exposure to imbalance charges and benefits the grid operators by reducing the need for grid upgrades to cope with excess exported electricity.
The more customers there are consuming electricity at the same time as the generator is producing electricity, the greater the benefits will be.
Next Steps
Both clients are keen to establish ‘complex sites’ to improve the viability of their projects and local electricity supply.
Key Facts
| Client | Southampton City Council/ Bath and West Community Energy |
| Strategic priority | New business model for renewable energy generation and local electricity supply |
| Energy generation/saving | 4.55GWh/yr generation |
| Timeline | Southampton likely to start rooftop solar installations in 2025 BWCE hope to start planning applications in 2025. |
| Carbon saving | ~900tnCO2/yr |
| Project value | If all the projects were built, total value would be £5.4m |
| Project website | Report to be published on our website Spring 2025 |
