How to Size a Solar Charge Controller for a DIY Camper Van Solar System
September 22, 2019 · 9 min · 363K views
What this video covers
Sizing an MPPT solar charge controller for a camper van or RV requires calculating two temperature-corrected figures: maximum array voltage at the coldest expected temperature, and maximum charge controller output amperage. Nate walks through both calculations using a 5-panel array of 100-watt Maya panels wired in series, with a worst-case low of negative 45°C drawn from a winter in British Columbia.2:27 The voltage formula applies the panel's temperature coefficient of Voc to find how much open-circuit voltage rises as temperature drops below the 25°C STC baseline — a naive multiplication of 22.65 V × 5 panels yields 113.25 V, but the cold-corrected figure is higher.2:24 The amperage calculation uses the temperature coefficient of Pmax to find elevated watt output at low temperature, then divides by the 14.4 V charging voltage rather than the panel's rated operating voltage.5:28 Both corrected numbers are cross-referenced against Victron SmartSolar charge controller model designations, where the first number is max input voltage and the second is max output amps; the example array maps to the Victron SmartSolar MPPT 150/60.6:54 A free JavaScript calculator Nate built accepts all panel spec inputs and returns the recommended controller size automatically.7:07
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