GP Surgery Solar Installation UK: From 300 Roof Leaks to a Live 100kW System

The two-video story

This is the case study that became KMM's first multi-video story. The first video (March 2026) shows the project before install: 300+ roof leaks, a partial solar system from a previous installer that wasn't generating properly, and a CQC-regulated practice that needed both energy savings and operational uptime. The second video (May 2026) is the post-install walkthrough.

The starting situation

A multi-partner GP surgery in Market Deeping, Lincolnshire, with 6 separate roof sections, around 320 m² of usable roof area in total, 4 GPs and 8 support staff. The practice had a partial 25 kWp solar system installed in 2019 by a now-defunct installer. It had never performed correctly: the previous monitoring portal was offline, two strings were underperforming, the inverter alarmed weekly. On top of that, the roof had developed roughly 300 leaks across the various sections following a 2024 storm.

The KMM brief

• Diagnose and remediate the existing solar system, or remove and replace
• Re-roof the affected sections (working with a roofing contractor)
• Design a new system sized for the surgery's full 24/7 load including medical-fridge backup
• Provide CQC-aligned ride-through backup for critical circuits (medical fridge, oxygen concentrator)
• Set up monitoring at panel-string level (so we'd catch any future underperformance immediately)

The KMM design

• System size: 100 kWp DC across all 6 roof sections
• Per-panel optimisation: Tigo TS4-A optimisers on every panel (because of the inter-roof shading across the 6 sections)
• Inverter: 2 × 50 kW SolaX commercial inverters with G99 commissioning
• Battery: 100 kWh commercial LFP (BYD Battery-Box Premium) with automatic transfer switch
• Critical circuit backup: dedicated EPS feed to medical fridge, oxygen concentrator, nurse-call and emergency lighting; 90-minute backup minimum
• Bird-proofing: 50 mm mesh on all panel undersides (Market Deeping has a substantial pigeon population)
• Monitoring: Sungrow iSolarCloud with daily auto-alarm to KMM ops team and the practice manager

The fix-the-previous-installer bit

One of the more unusual project elements. We removed the 25 kWp from 2019, inspected each panel, retained 22 that were still within spec (we ran IV-curve traces on every one), and re-deployed them as a sub-array on the new system. The remaining 8 panels were end-of-life and we recycled them through PV Cycle UK. The original inverter was beyond economic repair so we removed it and submitted the warranty claim to the previous installer's administrator.

The numbers

The CQC-aligned uptime detail

This is the bit that matters for healthcare. We specified the inverter and battery system with an automatic transfer switch routed only to the critical-circuit sub-board. During a grid outage, the solar+battery sits behind a 250 ms transfer switch and powers the medical fridge, oxygen concentrator, nurse-call panel and the emergency lighting for up to 90 minutes — long enough for the surgery to either restore grid or call in a backup generator if needed. The non-critical circuits (waiting room lights, IT, HVAC) lose power. CQC was happy with the documentation.

What this case study illustrates

Three things. First, retrofitting solar on a previously-installed roof isn't easy but is often the right answer — we recovered around £8,000 of usable panel value from the 2019 install. Second, panel-level optimisation matters more on complex multi-roof installations than on a single flat roof; Tigo TS4-A added around £4,500 to the project but lifted generation by an estimated 6-8% versus a string-only design. Third, the CQC ride-through capability isn't just a marketing claim — it requires specific engineering decisions made at the design stage, not bolted on afterwards.

For the full healthcare sector overview see our healthcare solar page, or watch the second video which goes deeper on the previous-installer remediation.