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Solar · Fitting

Do I need optimisers or microinverters if my roof is partly shaded?

Short answer

Not always. If shade hits only a few panels for part of the day, optimisers or microinverters can reduce the loss because each panel works independently. For unshaded single-direction roofs a plain string inverter is usually cheaper. MCS requires a shade factor and, where shading exists, a sun-path diagram with the quote.

Last checked 24 September 2026 · 1 source

In more detail

  • Shade factor SF = 1 - estimated loss (MGD 005 method).
  • MLPE datasheet must be supplied pre-contract (MIS 3002 4.2.1 d).
  • Roof-level electronics add failure points needing roof access.

The facts, dated

  1. 01
    Where MCS shading methodology is used, results should be within 10% of actual for most systems (estimate caveat) — 10 %

    standard · UK · checked 24 September 2026 · MCS

Sources

Last checked: 24 September 2026