ROCKSOLAR 40 A MPPT Solar Charge ControllerA 40 A MPPT controller for a 12 V or 24 V LiFePO4 or lead-acid battery, rated for 520 W of panels at 12 V or 1,040 W at 24 V: the typical RV roof, a boat, or a cabin with a fridge and lights. An MPPT controller tracks the panel's maximum power point and converts the surplus voltage into extra charging current, which is worth 20 to 30 percent more harvest than a PWM controller, most of it on cold, bright days and whenever the panel voltage sits well above the battery voltage.Choose this one for two to four full-size panels on a 12 V bank, or up to about 1 kW on a 24 V bank. The 100 V open-circuit limit takes a full-size panel, or two 12 V-nominal panels in series, with the rest in parallel.Keep the array's open-circuit voltage under the controller's PV limit on the coldest morning of the year, wire extra panels in parallel rather than in series, and fuse the battery side. Mounting and wiring are for reference; a licensed electrician should make the connections on a permanent installation.
