What are power optimisers and do I need them?
Power optimisers are small units fitted to each panel that let every panel perform independently, so shading or dirt on one does not pull down the whole string. They cost around £40 to £80 per panel and are worth it on shaded, complex or multi-direction roofs. On a clean, unshaded south-facing roof they are often unnecessary.
When optimisers help
- Shading from chimneys, trees or aerials on part of the roof.
- Panels split across several roof faces or angles.
- A desire for panel-level monitoring to spot faults.
- Long strings where one weak panel would otherwise limit output.
Optimisers vs microinverters
Both solve the same shading problem. Optimisers work with a central string inverter, while microinverters do the conversion at each panel. Optimisers are common in the UK and add panel-level monitoring. For a simple unshaded roof, a plain string inverter is usually all you need.
Frequently asked questions
- Do I always need optimisers?
- No. They mainly help shaded or complex roofs. A clean, unshaded single-direction roof usually does not need them.
- Do optimisers fix shading completely?
- They reduce its impact by isolating weak panels, but they cannot recover light that is blocked. Good panel placement matters too.
Related questions
Indicative estimates based on UK average data. Last updated 27 May 2026.