Solar Calculators

Solar design starts with honest load accounting and realistic sun data. Nameplate panel watts are laboratory figures. Real yield depends on tilt, azimuth, shading, temperature, soiling, and controller efficiency. A 400 W module might produce far less than its sticker suggests on a winter roof with partial shade and a PWM controller.

Array sizing ties directly to battery storage. Panels must replace daily consumption plus efficiency losses within available sun hours. Off-grid designers often target surplus summer production to carry lean winter weeks, or pair smaller arrays with generator backup. Neither approach is wrong—but the math must be explicit.

Charge controllers and inverter-chargers define how much of captured energy reaches the battery. MPPT controllers extract more from high-voltage strings. Inverter chargers limit AC pass-through and charging current. String voltage must respect controller maximums while staying above minimum operating thresholds in cold weather when panel open-circuit voltage rises.

Battery chemistry influences how aggressively you can charge from solar. Lead-acid wants staged absorption time. Lithium BMS systems may cap charge current independently of controller settings. Align all three layers—array, controller, battery limits—before purchasing hardware.

WattQuick solar calculators translate daily loads into rough array and storage targets, estimate seasonal yield, and help compare PWM versus MPPT scenarios. Re-run calculations when you add loads like DC refrigeration, Starlink, or a second inverter. Solar is iterative; your tool inputs should be too.