250 W Charge Controller

A 250 watt MPPT controller for a 12 or 24 volt bank, accepting up to 50 volts open-circuit at the input.

This is small-system sizing: one or two residential modules on a cabin, a shed, a monitoring station or an electric fence. MPPT tracking is still worth it here, because it recovers the module’s excess voltage and turns it into charge current instead of wasting it — fifteen to twenty percent over an equivalent PWM controller, and more in cold weather.

Check the 50 V open-circuit limit at the site’s coldest temperature, not at 25 °C. A module rated 46 V Voc can exceed 50 V at -25 °C and fault the controller. When in doubt, wire in parallel rather than in series.