Another thing to consider is that a boost converter has a negative
resistance input (pretty much). As you decrease the input voltage, the
current increases as it works to output the same power. When driving this
with a solar array, it can quickly run the array voltage down to zero.
There are "maximum power point trackers" that adjust the load on the array
to get the maximum output power. I worked on one of these for a solar
powered car project. This car had a bunch of solar panels, each getting
different illumination. We did a pic controlled boost converter on each
panel. The PIC watched the output current (the current into the battery
from this particular converter) and adjusted the switch duty cycle to
maximize that current.

Harold


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