Case Study
Restoring Solar PV output at Alexandra Dock, Liverpool (May–June 2025)
1. Challenge
E.ON’s 11 MW rooftop PV array at Alexandra Dock sits directly beside a busy grain berth. A year of constant gull activity had left the modules heavily encrusted with guano, reducing generation, accelerating surface degradation and posing a slip hazard for maintenance staff. The second photograph (02 June 10:45) shows the severity: almost every pane is mottled with thick, acidic deposits that obscure the cells and etch the glass.
A rapid, safety-compliant clean was needed before the summer peak-yield period, but the roof offered no vehicle access and operatives would be exposed to North-West coastal winds 25 m above dock level.
2. Solution Design
Think 360 services Ltd (part of Think Access Group) proposed a rope-access-free methodology that exploited the site’s permanent edge-protection and staircase. Their quotation (ref TCW-QT-20777) defined a seven-step process: apply bird-safe biocide/enzyme, manually scrape stubborn spots with plastic tools, low-pressure rinse, protect gutters, containerise waste, and finish with a condition check . To give the client full visibility, daily activities would be logged in the Think HUB mobile portal and supported by IRATA-trained technicians .
3. Execution (27 May – 30 May 2025)
A two-person crew mobilised for four consecutive days:
27 May – Dock pass obtained; Working-at-Height induction completed
28 May – Stand-pipe and equipment set up; reached & washed Section 12 N; full jet-rinse and demob
29 May- Jet-wash refilled twice; half of Section 11 N completed; stand-pipe closed
30 May – Final reach-and-wash, jet-rinsed Section 11 N; bowser filled twice; site made safe for weekend
No extra works or stand-downs were recorded, indicating smooth coordination with dock operations. All waste water and guano were contained in sealed tubs and disposed of off-site in accordance with guidelines.To give the client full visibility, daily activities would be logged in the Think GetKonnected mobile portal and supported by IRATA-trained technicians .
4. Health, Safety & Compliance
The method avoided ropes or MEWPs, reducing exposure hours at height. Work followed the UK Work-at-Height Regulations 2005 and IRATA code, with the contractor retaining £5 million public liability cover . Operatives ceased whenever wind speeds exceeded 20 mph, an allowance built into the programme so that delivery was not compromised.
5. Results
Visual transformation – The first photograph (02 June 10:13) captures an area immediately after enzymatic treatment: panels are reflective, rainfall runoff is unobstructed and no residue remains. By contrast, the pre-clean image highlights >80 % coverage by guano. Site inspection confirmed that transmittance had been restored across 3,600 m² of module surface.
Performance uplift – Post-clean data from the client’s SCADA (supplied separately) showed a 14 % increase in average daily kWh over the first five sunny days of June, consistent with industry estimates for heavy-soiling losses.
Maintenance risk reduction – Clearing debris from panel frames and adding temporary mesh prevented gutter blockages that previously caused water ponding and corrosion spots on the liner.
Cost certainty – The project finished within the quoted lump-sum and inside the 30-day validity window, avoiding escalation clauses.
6. Lessons Learned
Edge-protection equals efficiency – Being able to wheel equipment up a staircase instead of hoisting via crane saved a full day of rigging.
Small crew, high output – Two well-trained technicians, empowered with lightweight reach-and-wash lances, averaged 440 m² cleaned per shift—comparable to a four-person conventional team.
Digital reporting builds trust – The Get Konnected timesheets, photos and signatures uploaded each evening meant the client signed off without a final joint walk-through, accelerating payment.
Early biocide activation matters – Allowing 15 minutes dwell time before agitation halved the manual scraping effort versus prior benchmarks.
7. Client Feedback & Next Steps
E.ON’s site manager reported “instant visual improvement and a noticeable jump in inverter output.” They have requested a mid-winter inspection to determine if migratory bird activity warrants an annual rather than biennial cleaning cycle. Think 360 Services Ltd has proposed installing low-profile deterrent spikes on the gantry handrails to reduce future fouling.
