3 How to Achieve Solar Battery Charging with VINDPM

For the solar use case, VINDPM is more applicable than IINDPM. Set the VINDPM of the battery charger at the MPP to extract maximum power from the solar panel. By the nature of the battery charger, if users try to request maximum current, then this browns out the adapter. However, fixing the VINDPM keeps the input voltage at the correct operation point. To make use of VINDPM, the battery charger needs to have sufficient VINDPM step resolution to be able to zero in on the MPP.

An algorithm is needed to get a good MPP throughout the charge cycle as the environmental conditions change. The best way to do that is to measure the charge current at each VINDPM setting and keep the VINPDM fixed at the setting that gives the most charge current. For a fixed battery voltage in the short term, whatever input voltage gives the most charge current is the MPP.

There are two scenarios (assuming no system load). First, the charger is in VINDPM with the setting that gives the most charge current. This indicates operation at the MPP. Second, the charger is not in VINDPM while the full charge current is realized. This indicates the solar panel has more energy to provide than is requested.