Shading, optimisers and microinverters Do you need optimisers or microinverters?
Only if your roof is partly shaded or your panels face different ways. On a clear, single-direction roof, a standard string inverter does the job, and optimisers add cost without adding much. Here's how each works.
The standard setup: a string inverter
Panels are wired together in a "string" to one inverter. It's simple and cost-effective. The drawback is that, in a basic string, the output can be held back by the weakest panel, so shade on one panel can pull down the rest.
Three ways to wire a system
| String inverter | String inverter with optimisers | Microinverters | |
|---|---|---|---|
| How it works | One inverter for the whole string | A small box on each panel manages it, feeding one inverter | A small inverter on each panel, turning its output to AC on the roof |
| Shade | One shaded panel can hold back others | Limits the effect of a shaded panel on the rest | Each panel works independently |
| Monitoring | Whole system | Panel by panel | Panel by panel |
| If a part fails | The whole system stops until the inverter is fixed | Usually just that panel's optimiser | The rest keep running |
| Cost | Lowest | More | Usually most |
Optimiser and microinverter benefits are partly manufacturers' claims (SolarEdge and Enphase). The Energy Saving Trust's independent view: optimisers limit the effect of shading but add nothing where there's no shade.
When they're worth it
- Part of the roof is shaded by a chimney, a dormer, a tree or a neighbouring building for some of the day.
- Panels are split across two or three roof slopes facing different ways.
- You want to see each panel's output.
The catch: optimisers and microinverters are electronics on the roof. If one fails, someone has to get up there. Ask about their warranty: Enphase, for example, offers 25 years on its IQ microinverters.
Questions people ask
Do I need solar panel optimisers?
Only if part of your roof is shaded or your panels face different directions. On a clear, single-facing roof they add cost without much benefit.
Optimisers or microinverters: which is better?
Both deal with shade. Microinverters make each panel fully independent; optimisers work with a central inverter. The right choice depends on your roof and budget.
Do optimisers work with a battery?
Many do, through a compatible inverter. Check compatibility before choosing a battery.
Can optimisers be added later?
It's possible but means going back on the roof. It's better to decide at the design stage.
Read next
Sources
Figures and rules on this page were checked on 11 October 2026. Schemes, tariffs and prices change, so check the latest before you decide.
- Energy Saving Trust: Solar panels, costs, savings and benefits, updated 1 October 2026
- SolarEdge: Power optimisers (manufacturer information), checked 11 October 2026
- Enphase: Home solar systems (manufacturer information), checked 11 October 2026
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