Cable sizing, voltage drop, string configuration, battery banks and energy yield — with the formulas, the assumptions and the limits written out. Free, instant, and everything runs in your browser.
DC, single-phase and three-phase. Temperature corrected, copper or aluminium, parallel runs, reverse sizing.
String length vs inverter MPPT window, with cold-temperature Voc check.
Capacity from daily load and autonomy days, with depth-of-discharge derating.
Annual kWh from location, tilt, azimuth and array size.
AWG, kcmil and mm², with resistance per kilometre.
What cable losses actually cost you per year.
Most online calculators give you a number and nothing else. If you are signing off a design, that is not good enough — you need to know what was assumed. Every calculator here publishes the formula, the constants, and the cases where it stops being accurate.
Where a wiring code governs the answer, we say so and stay out of it. These tools handle the physics; the code compliance is yours to confirm.