Should you wash your solar panels?
A homeowner conducts a DIY experiment to quantify the benefits of cleaning solar panels, finding a modest efficiency boost. The real head-scratcher emerges when considering upgrades, as legacy feed-in tariffs create perverse incentives against modernizing. This story appeals to HN's love for data-driven, practical problem-solving mixed with a dash of policy wonkery and unexpected electrical adventure.
The Lowdown
James Stanley, a solar panel owner, embarked on a personal quest to determine if cleaning his visibly dusty 15-year-old solar panels was a worthwhile endeavor. Through a methodical experiment, he aimed to quantify the impact on power output and assess the financial implications.
- Methodology: Stanley cleaned one of his two 8-panel banks, meticulously tracking the power output ratio between the cleaned and uncleaned sections to neutralize variables like sun angle and cloud cover. He took readings before, during, and after the cleaning process.
- Results: The experiment indicated a 2-5% increase in power output, potentially yielding an extra £60-£150 annually. Stanley noted curious fluctuations in the data, including an initial drop and a post-cleaning dip, speculating on causes like panel matching effects or cooling from the water.
- The Tingle: A surprising anecdote involved experiencing an electrical 'tingle' while cleaning. Initially dismissed as a splinter, he later, with ChatGPT's help, attributed it to possible capacitive leakage from his transformerless inverter, deciding to clean only after dark in the future.
- Upgrade Dilemma: The most significant challenge arose when considering an upgrade. While newer panels could increase output by 60% with a quick 3-year payback, doing so would mean forfeiting a highly lucrative, generation-based 'feed-in tariff' from his original installation, rendering a seemingly sensible upgrade financially detrimental.
Ultimately, cleaning was deemed 'just about worthwhile,' but the exploration of upgrading unveiled a fascinating and frustrating example of how well-intentioned market-distorting incentives can complicate rational decision-making years down the line, turning today's encouragement into tomorrow's disincentive.
The Gossip
Panel Polishing Pragmatics
Commenters largely agree that cleaning solar panels is beneficial, with some reporting significantly higher gains (e.g., 35-40%) than the author's 2-5%. There's a lively debate about whether natural rain adequately cleans panels, with many arguing that typical rainfall isn't sufficient to remove accumulated grime, often just caking it. Suggestions for automated spraying systems are also discussed, balanced against safety concerns for roof-mounted panels.
Shocking Safety Scrutiny
The author's account of an electrical 'tingle' and subsequent consultation with ChatGPT sparked considerable concern. Commenters emphasized the importance of proper electrical grounding and bonding for solar panel systems, suggesting that relying on AI for safety advice regarding potential electric shocks is highly inadvisable. The discussion touched on the requirements for grounding in transformerless inverter setups.
Tariff Troubles & Upgrade Hurdles
The intricacies of the UK's 'feed-in tariff' system were a major point of discussion. Commenters concurred that these legacy subsidies create a powerful disincentive to upgrade older, less efficient solar systems, as modernizing would mean forfeiting the highly favorable rates. The conversation explored the historical context of these subsidies, their current impact on upgrade decisions, and whether solar energy still requires such 'artificial' support today. Some suggested strategies like installing new panels as a separate system to retain the old tariff.
Presentation & Perceived Prudence
Several commenters extended the discussion to the psychological impact of cleanliness, particularly in the context of selling a home. They argued that clean and well-maintained panels, much like a tidy house, signal to potential buyers that the property has been cared for, potentially leading to a higher sale price. This touches on the broader concept of 'home staging' and how perceived maintenance influences value, even if the cleaning itself doesn't directly add monetary worth beyond its cost.