Solar maintenance yields modest returns as tariff structures stifle upgrades
A recent experiment by solar farm owner James Stanley indicates that cleaning dusty panels can boost output by up to five per cent, yet existing feed-in tariffs render system modernisation economically unviable for many investors.
James Stanley, a solar farm owner, conducted a self-reported experiment to determine if cleaning visibly dusty solar panels improves power output. The experiment involved cleaning one bank of eight panels while monitoring the power ratio against an uncleaned bank. Stanley observed a 2%-5% increase in power output, estimating an annual financial benefit of £60-£150.
The experiment utilised a comparative method, measuring the ratio of power output between two banks of eight panels to account for variable weather conditions such as cloud cover and sun angle. Initial attempts to clean panels using window cleaner and paper towels were deemed ineffective; soapy water and a cloth were subsequently used.
An anomaly was observed where the power ratio dropped significantly after the first panel was washed, before rising as more panels were cleaned. A post-cleaning drop in the power ratio was observed, which Stanley hypothesised might be due to water evaporation causing a "frosted glass effect" on the panel surface.
The solar farm consists of 16 panels installed approximately 15 years ago, with a peak output of 3.7 kW. Stanley noted a minor electrical "tingle" during cleaning, attributing it to capacitive leakage from an inverter without a transformer, though he acknowledged the risk.
Stanley concluded that while upgrading to modern panels could increase output by 60%, existing feed-in tariffs make replacement financially unviable at this time. The feed-in tariff applies to the existing capacity but not to any additional capacity generated by a system upgrade, reverting new output to current, lower prevailing tariffs.
