Mppt

EC MPPT algorithm

Overview

This describes the MPPT algorithm present in the XO-1.5 embedded controller. When operating from a PV solar panel the available power can be very dynamic even in seeming very sunny conditions. In many cases the maximum power available from the solar panel is less than the maximum power draw of the XO-1.5. The maximum power input to the XO-1.5 is 25W but the most common OLPC solar panel in use is only rated at 10W. This can create up to a 15W power deficit.

The voltage output of a PV panel is related to its ouptut current. The VI curve for the OLPC panel looks like this

As the current draw increases from the panel the voltage decreases. This creates a power curve that looks like this

So the the maximum power point of a PV panel is obtained when you maximize both the voltage and the current.

Assumptions

More on this after I sleep

Flow Chart

Wikimedia seems to hate trying to render my .svg . Here's a link to the .svg file Media: mppt.svg

Flowchart

The dia file is also available.

File:Mppt.dia

And here's the same thing as pdf:

File:Mppt.pdf