Solar Array Sizing Calculator
Turn daily Wh, local peak sun hours, and MPPT efficiency into a required array size. See suggested panel wattages and counts.
What are Peak Sun Hours (PSH) and where do I get them?
PSH condense a day’s varying sunlight into equivalent hours at 1,000 W/m². Use a solar map/app for your **location and month** (summer vs winter can differ 2–3×).
How much efficiency should I assume for MPPT and wiring?
85–95% is typical. Quality MPPTs are high-90% at good operating points, but **heat, wiring drop, and panel mismatch** pull the effective number down. If unsure, use **90%**.
Should I size for summer, shoulder seasons, or winter?
If you’re traveling year-round, size for the **leanest month you care about** or add a **generator/alternator/DC-DC** plan for deep winter.
Do I need series or parallel?
Choose **series** to hit your controller’s **MPPT voltage window** efficiently; add **parallel strings** if current limits allow and shade patterns differ. Confirm with “MPPT Controller Picker” and “Series vs Parallel Optimizer”.
Why does your suggestion include multiple panel wattages?
Roof real estate and mounting constraints matter. The tool proposes **several mixes** (e.g., 2×250 W vs 3×150 W) so you can match **dimensions, weight, and routing** without under-sizing.