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Cab Tools

Cab solar panel sizing calculator

Daily watt-hours in, peak sun hours in — get the panel wattage that covers your cab, plus how long the battery carries you with no sun.

Cab Solar Panel Sizing Calculator

Pick the setup closest to yours. A 25 W fridge averaging 12 h a day is about 300 Wh — phone, fan and lights on top.

Size for your worst month, not July. Winter sun is the low end everywhere.

Used only for the days-of-autonomy check below — how long the bank carries you with zero sun.

Recommended panel size
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Less than a day of backup. One overcast day and the bank is flat — grow the battery bank or trim the daily load before buying panels.

Beyond a typical cab-roof setup. A sleeper roof fits roughly 200–400 W of rigid panels. Past that you are into trailer or ground-deploy territory.

  • The 0.75 system factor is a planning estimate covering charge-controller and wiring losses — not a measured result.
  • Panels are sold in fixed sizes (100 W, 200 W …) — round the recommendation up to real panels, and buy an MPPT controller.
  • Flat roof mounts lose output versus tilted panels, especially in winter sun. Size for December, enjoy the surplus in July.
  • Solar tops the bank up by day — the battery still has to carry every night on its own.