500 W MPPT Charge Controller

An MPPT controller accepting up to 500 W of panels and an open-circuit voltage of 100 volts. It detects a 12, 24 or 48 volt bank on its own, which removes one configuration mistake at commissioning.

The headroom up to 100 V opens the door to series wiring. Three modules at 36 V open-circuit stay under the limit even in deep cold, and let you run 90 V over a long distance between the array and the equipment room — on much thinner cable than low voltage would need. Always check your modules’ Voc at the site’s coldest temperature: that is when it climbs, and that is the number that must stay under 100 V.

On a 48 V bank, 500 W of input gives roughly 10 A of charge current; on a 12 V bank, closer to 35 A. Size the wire for the current on the battery side, not for the panel wattage.