Historic buildings present a particular set of challenges for solar installation. St Peter & St Paul's Church in London is a working place of worship with a congregation to serve, operational costs to manage, and a fabric that demands careful handling. When the church approached ProStar Energy about reducing its energy bills, the brief was straightforward: deliver a system that performs reliably, causes minimal disruption to the building and its community, and makes sound financial sense over the long term.
The result is a 21 kWp solar PV system that is now generating meaningful savings from day one, with a full payback period of under six years and an annual carbon offset of 5 tonnes of CO₂.
System Capacity: 21 kWp
Total Project Cost: £33,658
First-Year Savings: £5,418
Annual ROI: 16.10%
Estimated Payback Period: 5 years 9 months
Annual Carbon Offset: 5 tonnes CO₂
Challenges and Solutions
Working with a Heritage Setting
Churches are rarely straightforward installations. Roof geometry, structural constraints, listed status considerations, and the need to preserve the building's character all add complexity that a standard commercial survey simply would not account for. Before any design work began, our engineers carried out a full site assessment to understand the roof orientation, available surface area, load-bearing capacity, and any planning requirements specific to the property.
That groundwork determined everything that followed. The 21 kWp system was designed around the building's actual constraints rather than an idealised layout, which is the only way to produce accurate performance projections and avoid costly adjustments during installation.
Minimising Disruption to an Active Site
A church is not a factory or an office block. Services, community events, and pastoral commitments run to their own schedule, and any installation work had to fit around them. ProStar Energy coordinated closely with the church throughout the project, agreeing access windows in advance and managing the installation programme to avoid clashes with the congregation's calendar. The site was kept tidy and safe at all times, and handover was completed on schedule.
Delivering Value on a Constrained Budget
Faith organisations operate on tight margins, and the decision to invest in solar is rarely taken lightly. The system design needed to be efficient enough to deliver a credible return without overspending on capacity the building could not use.
The 21 kWp specification was arrived at through careful analysis of the church's energy consumption patterns, ensuring that the system generates in proportion to actual demand and that savings are realised rather than exported unnecessarily.
Key Results
- £5,418 saved in the first year of operation.
- Payback achieved in an estimated 5 years and 9 months.
- 5 tonnes of CO₂ offset annually, contributing to the church's environmental responsibilities.
- System designed and installed with no disruption to church services or community activities.
- Full manufacturer warranties in place, tracked through ProStar Energy's CRM for ongoing peace of mind.
- Two-year workmanship warranty backed by available servicing packages.
A Long-Term Investment for the Community
For St Peter & St Paul's Church, this installation is more than an energy efficiency measure. The savings generated each year can be redirected into the work of the congregation, reducing the pressure that rising energy costs place on charitable and community budgets. At the same time, the carbon offset contribution reflects a commitment to environmental stewardship that many faith communities hold as a core value.
The system will continue to generate returns well beyond the payback period, with modern solar PV panels typically performing reliably for 25 years or more. That long-term outlook is what makes solar a sound investment for institutions that think in decades rather than quarters.
If your organisation is considering commercial solar PV panels and you want a clear picture of what it could realistically deliver, the first step is a free site survey. Get in touch with the ProStar Energy team below or call us on 03316 302 225 to arrange an assessment.
