Charge Controller Ratings

When selecting a charge controller, consider both its voltage and current ratings. Most of the charge controllers featured here can be programmed or configured to operate at different nominal battery voltages, but double check that the controller you select is compatible with your system's nominal battery voltage.

All PV charge controllers have an absolute maximum open-circuit voltage (Voc) rating. Exceeding this rating can damage the controller, and overvoltage-related failures are not covered under warranty. Because module voltage increases as temperature decreases, a temperature correction factor based on the historic lowest temperature at your site must be considered when determining the voltage of your PV array.

A controller's rated amperage should typically be 1.25 times the PV array's 25°C short-circuit current (Isc) rating (to account for edge-of-cloud or other enhanced irradiance effects and to meet National Electrical Code requirements), or 1.56 times the array Isc if the charge controller is not rated for continuous operation at rated current. Most maximum power point tracking (MPPT) controllers (described below) include an electronic current limit function, and are subject to the 1.25 derate factor. MPPT controllers operating in step-down voltage mode will have a significantly higher output current than input current. If you're using your controller in step-down mode, the output current needs to reflect the controller's current rating specification.

DIY Battery Repair

DIY Battery Repair

You can now recondition your old batteries at home and bring them back to 100 percent of their working condition. This guide will enable you to revive All NiCd batteries regardless of brand and battery volt. It will give you the required information on how to re-energize and revive your NiCd batteries through the RVD process, charging method and charging guidelines.

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