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How do you check a roof can carry solar panels?

Short answer

MIS 3002 requires a competent structural check. For trussed rafters, take 0.785 kN/m² dead load less the existing covering, or 0.75 kN/m² imposed load less snow. For cut roofs, use TRADA span tables. Hips, valleys, asymmetric roofs, pitches below 30°, altered or distressed roofs and snow traps need a structural engineer. Keep modules 400 mm from edges.

Last checked 24 September 2026 · 1 source

In more detail

  • MIS 3002 cl.5.9.4-5.9.7 and Table 1.
  • Edge zone: extra fixings/timbers, secure ridge tiles, run-off and snow shedding, wind noise if within 400 mm.
  • Flat roofs: pull-out tests (SPRA S15-19); ballast friction coefficient 0.3 unless tested; structural engineer for ballast load; BRE Digest 489 wind coefficients.
  • Non-MCS-012 systems: structural and wind-load calculation evidence required (cl.5.5.5).

The facts, dated

  1. 01
    Trussed rafter typical design dead load used in MIS method — 0.785 kN/m2

    standard · UK · checked 24 September 2026 · MCS

  2. 02
    Minimum distance from roof edge without special measures — 400 mm

    standard · UK · checked 24 September 2026 · MCS

  3. 03
    Default coefficient of friction for ballasted systems — 0.3

    standard · UK · checked 24 September 2026 · MCS

Sources

Last checked: 24 September 2026