Datasheet

Design Notes

Is this a Max Power Point Tracker (MPPT)?

This design is not a 'true' MPPT, and we did that for a reason! Max power point trackers

work by 'tracking' the voltage and current curve of a solar panel so that the total Power

(Voltage * Current) is maximized. This means that as the light changes, the voltage and

current must be carefully tracked. In general, the way controllers perform MPPT is to have a

DC/DC converter - that's because to have the best power conversion you'll want DC/DC not

linear converters (that lose any excess voltage as heat). For example, say you want to

charge a 6V lead acid battery and you have a 12V (approx) panel. The voltage will range

between 9V and 14V depending on current draw and visible light. The buck converter will

do its best to keep the current draw so that the total power available at the output is

maximized.

This diagram from Linear (http://adafru.it/aMN) is really good at describing how it works:

The Green lines show the I-V curve of the panel for a given light condition. As the light