While the code is still in progress, and the prototype remains in its not-quite-there-yet breadboard form, I got one great piece of test gear: A watt meter. Basically a fancy multimeter thing that measures voltage and current, and calculates the amount of power passing though. I've been using it here to measure the power coming in from the solar panel, and on good days, I've been getting up to 4W into the solar charger prototype and the battery behind it.

There are a few things I realized while doing this:

• While most of the time, voltage measurements on the watt meter and on the charger are reasonably close, sometimes they're quite a bit off. This is probably due to the not-so-great wiring job I've done on the breadboard. So one of the next things to do is really put this on protoboard. I do have to exchange some parts before that though, but that leads me to a second thing
• I'm missing a comparison. I have a chinese cheap-o solar charger, which I'm trying to at least come close to in terms of performance. But I can't actually compare them side-by-side, so I'll need a complete second setup (solar panel + battery) to actually do any comparisons.
• When in full sun, the algorithm for controlling the charging MOSFET went all over the board again, despite the fixes I did last time. I looked at some other projects, and went back to a much simpler implementation again, which works so much better.

The next steps now are going to be:

• Finally find a place for the source code online
• Get a new solar panel
• Exchange some parts, add the load MOSFET, test it on the breadboard and then build it on protoboard for more solid connections

However, there's another project that'll need my attention in the meantime, so looks like this will have to wait for a week or three.