Commercial solar project for Gavels Auctioneers – Caerphilly

THE CHALLENGE

Rising Energy Costs Were Eating Into the Bottom Line

Running a busy commercial auction house is energy-intensive. Lighting sprawling warehouse floors, powering offices, running CCTV systems, and managing the logistics of high-volume auction days all add up to significant electricity consumption — and significant bills.

Before installation, Gavels Auctioneers was paying an average of £963.62 per month on electricity, at a rate of around 30p per kWh. In early 2023, the decision was made to take control: invest in on-site renewable generation and turn the roof into a working asset.

On 6 June 2023, Modern Energy and Electrical Services commissioned a 50kW SolarEdge rooftop photovoltaic system — designed and installed by a team with 15 years of experience in commercial solar.

“The roof was always there. Now it works for us every single day.”

THE RESULT

Monthly Bills Cut by Nearly Two-Thirds

The most immediate, tangible impact of the installation has been on the monthly electricity bill. Within the first full year of operation, Gavels Auctioneers saw its average monthly spend fall dramatically.

THREE YEARS OF REAL-WORLD DATA

Performance That Exceeded Every Projection

When the system was specified, modelling suggested annual generation of around 46.9 MWh per year — a three-year total of roughly 140.7 MWh. From commissioning on 7 June 2023 through to 16 June 2026, the system has actually produced 145 MWh cumulative — ahead of pace, and still climbing with every day of sunshine.

That 145 MWh figure is a running lifetime total, not an annual one — and it will keep rising year after year as the system continues to generate. Monthly data confirms strong, consistent performance, with output regularly pushing above 8 MWh during peak summer months and no signs of degradation after three full years in operation.

FINANCIAL IMPACT

A Faster Payback. A Stronger Return.

The original business case for the installation was already compelling. Based on a 30p/kWh electricity rate, the projected figures were:

Ahead of Schedule — And Still Climbing

145 MWh generated over three years comfortably outpaces the ~140.7 MWh that the original 46.9 MWh/year projection would suggest — and that lifetime total keeps growing with every year of operation. Output running ahead of plan means the payback period is on track to land earlier than the projected 4.9 years, strengthening the IRR and ROI figures further over the system’s operational lifetime.

BEYOND THE BILL

A Sustainable Business Model for the Long Term

The financial case is clear — but the benefits of commercial solar extend well beyond the electricity meter. For Gavels Auctioneers, the installation supports a broader business strategy built on resilience, responsibility, and forward thinking.

• Free daytime electricity— every kWh generated on-site costs nothing once the system is paid back. Lights, systems, and operations run on sunshine.
• On-site EV charging— the solar array directly supports electric vehicle charging infrastructure, future-proofing the site for staff and customers transitioning to EVs.
• Improved cash flow— a near-70% drop in monthly outgoings frees up working capital that can be reinvested into the core business.
• Green credentials for supply chains— buyers, vendors, and commercial partners increasingly scrutinise the sustainability credentials of the businesses they work with. A verified solar installation is a meaningful signal.
• Improved brand positioning— demonstrating environmental responsibility builds trust with environmentally-conscious customers and positions Gavels as a modern, forward-thinking auction house.
• Energy independence— reducing reliance on grid electricity provides insulation against future market volatility and price shocks.

ENVIRONMENTAL IMPACT

The Carbon Case Is Just as Strong

Generating 145 MWh of clean electricity on-site has a measurable environmental impact, tracked directly through the system’s monitoring platform.

For a business that works with auction buyers, vendors, and corporate clients increasingly focused on supply chain sustainability, figures like these aren’t just good for the planet — they’re good for business relationships too.

THE TECHNOLOGY

Why SolarEdge for Commercial Installations

The system at Gavels was specified with SolarEdge technology across a single inverter and 57 power optimisers — the platform of choice for commercial installations that demand real-world performance, detailed monitoring, and long-term reliability.

SolarEdge’s optimiser-based architecture means each panel operates independently, eliminating the chain-effect losses that affect traditional string inverter systems. On a commercial rooftop where shading, panel orientation, and soiling vary across a large array, this translates directly into more generation — and more savings.

The monitoring platform provides full visibility into monthly, quarterly, and lifetime performance, letting the business track exactly how the system is performing against expectations, in real time.

KEY TAKEAWAYS

What Three Years Has Proven

The Gavels Auctioneers installation is a live, real-world demonstration of what commercial rooftop solar delivers when properly specified and commissioned by an experienced team.

For any commercial property owner in South Wales asking whether solar makes financial sense — the answer from Gavels Auctioneers, three years in, is an unambiguous yes.