Solar panels producing less power than expected — Haarlem, Noord-Holland

When your solar panels generate noticeably less electricity than their rated output — your electricity bill creeps up, the monitoring app shows declining production, or you're producing far less than neighbors with similar systems — the cause is usually one of a few fixable issues. Dirty panels (dust, pollen, bird droppings, tree sap) can cut output by 15–25%. Partial shading from a tree that grew since installation can drop an entire string's production. A failing inverter — the component that converts DC from panels to AC for your home — is the most common hardware failure, typically after 10–15 years. Loose or corroded wiring connections degrade over time and reduce current flow. A licensed solar electrician can diagnose the issue with monitoring data, visual inspection, and electrical testing, then clean panels, replace the inverter ($1,500–$3,500), trim shading, or repair wiring. Most residential solar systems carry 25-year panel warranties and 10–15-year inverter warranties — check before paying out of pocket.