Calculator
Charge controller amps & MPPT vs PWM
Size the solar charge controller current and see whether MPPT or PWM suits your array and system voltage, including a 25% safety headroom.
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Looking for a definition or a quick answer? See the solar & battery glossary for terms used on this page, or the FAQ for common sizing questions. For the full explanation, read the MPPT vs. PWM guide.
Sources & standards
- NFPA 70 — National Electrical Code (NEC), Articles 690 & 705 — Governs PV source/output circuits (Art. 690) and interconnected power production sources (Art. 705) in the US.
- IEEE 1013 — Recommended Practice for Sizing Lead-Acid Batteries for Stand-Alone Photovoltaic Systems — Widely used engineering practice for days-of-autonomy and depth-of-discharge sizing methods, referenced here for the general sizing approach.
Estimates for planning only. Verify with a meter and follow NEC / local code; have a licensed installer confirm any system before purchase or wiring. See the methodology for formulas and sources.