Commissioning is the formal handover when the solar PV system transitions from construction phase to operational phase. Done right, it produces a system that delivers its modelled yield year after year for 25+ years. Done badly, it produces a system that under-performs from day one and slowly deteriorates. Here's what proper farm solar commissioning looks like.
Commissioning tests we run on every install
Electrical safety testing per BS 7671: insulation resistance per panel string (minimum 1 MΞ© at 500V DC); polarity verification on all DC strings; RCD testing on AC side; earth bonding verification; protection device coordination tests; emergency shutdown function tests.
Functional testing: inverter startup sequence verification; MPPT optimisation function; grid synchronisation behaviour; export limiting function (if no-export design); monitoring portal data flow; alarm escalation routing.
Performance baseline: first-day generation curve recorded; expected output at peak irradiance verified; module-string-level performance recorded for future degradation comparison.
MCS commissioning paperwork
The MCS commercial certificate is the regulatory keystone for the install β without it, your SEG application will be rejected and your insurance position is weakened. We submit MCS paperwork within 14 working days of commissioning. The certificate confirms: installer MCS commercial certification; design conformance to MCS standards; commissioning test results; equipment serial numbers (panels and inverters); installation address and system specification.
Monitoring portal setup
Every commercial PV install includes a monitoring portal showing real-time generation data, daily/weekly/monthly/yearly totals, alarm history, and module-level performance (on SolarEdge optimised systems). The most common UK commercial monitoring platforms: SolarEdge Monitoring (premium, module-level data); SMA Sunny Portal (mature, well-established); Huawei FusionSolar (excellent UI, growing); Fronius Solar.web (Austrian engineering quality); Goodwe SEMS Portal. Each platform provides real-time alerts via email and SMS for: zero-generation alarms (inverter offline); under-performance alarms (PV string fault); communication-loss alarms (network connectivity); over-temperature warnings.
We set up portal access for the farm operator and (optionally) for our remote monitoring team. We provide brief training on portal navigation, daily/weekly/monthly performance interpretation, and alarm response.
Performance ratio targets
Performance Ratio (PR) is the standard metric for PV system efficiency β it compares actual generation against theoretical maximum for the given irradiance. For well-designed UK farm rooftop installs, PR should sit at 0.82-0.88 (82-88%) in year one. Below 0.78 indicates a problem (shading, equipment fault, string imbalance); above 0.90 is unusually high and typically a measurement artefact.
Long-term PR degradation: typical 0.5-0.6% per year for tier-1 modules with proper maintenance. After 25 years, expect PR to be 87-90% of year-one performance β meaning a 200 kW install delivering 180 MWh in year one would deliver ~157-162 MWh in year 25. This degradation is forecast in the original PVSyst model and accounted for in the 25-year DCF financial model.
Annual performance review
We deliver an annual performance review to every client showing: actual generation vs forecast; performance ratio trend; module-level degradation analysis (where SolarEdge or comparable optimisers fitted); inverter performance and any recommended maintenance; recommendations for any operational adjustments (e.g., panel cleaning schedule, vegetation management around the array).
Maintenance schedule
Commercial PV systems require minimal maintenance but not zero. Annual schedule: visual inspection of panels (any soiling, damage, or hot-spots); cleaning if soiling is severe (typically once per 3 years on rural farm sites); inverter air filter clean; cable inspection; mounting hardware torque check; performance review against benchmark. Cost typically Β£400-1,200 per year for a 200-500 kW install. We offer maintenance contracts at fixed price annually; clients can also use their own preferred maintenance contractor.
Fault response and escalation
When monitoring portal raises an alarm, the standard response path: immediate (within 1 hour during business hours) β automated email/SMS to farm operator and our monitoring team; within 4 hours β remote diagnostic from our monitoring team; within 24 hours β on-site visit if remote diagnosis confirms physical fault; warranty claim if covered fault.
Most faults resolve remotely or with a single on-site visit. The most common faults: inverter communication loss (resolves on power cycle); string-level shading change (vegetation growth around the array); panel hot-spot (covered under panel manufacturer warranty); inverter component failure (covered under inverter manufacturer warranty, typical replacement 5-15 years post-install).
Why ongoing monitoring matters
PV systems generate based on solar irradiance β there's no "are we running" signal like a heated greenhouse. Faults can go undetected for months without active monitoring. We've seen retrofitted clients with 12+ months of undetected inverter offline, losing Β£15,000+ of generation before the fault was noticed. With active monitoring, the same fault resolves in 24-48 hours.
Monitoring is included as standard for the system life β there's no separate subscription. Optional remote monitoring service (where we actively respond to alarms on your behalf) is typically Β£200-600/year and pays for itself in faster fault resolution alone.