> Ok, so modify the software flow for a simple MPPT, the uP
> scans through the PWM range looking for either the target current
> supply, or if it can't reach that, goes for the peak current level.
>
> Also, I would guess that if I can meet the target current supply (ie
> the cell can supply more) then it would probably meet these at 2 points
> on the PWM range,

Yes.

> so I would guess that the one that had the highest
> solar voltage would be the better one to pick. So perhaps that can also
> set the PWM scan to start from a low on duty cycle.

I don't see why it matters, except maybe your buck converter might be a
little more efficient at a higher voltage.  But why stop at the current
"target" unless higher current will actually damage the battery?

> does that come closer to a better solution?

Yes.

> Given that this routine will track the maximum current output via
> varying a PWM signal, I can't see the need to open cct the solar
> cell and check the voltage there. Am I missing something?
> (If I was using a fixed look up table then I can see the need).

Ha, ha.  Now this discussion has finally come full circle.  That's where
it started.  No, you don't need to know the panel voltage or current.  All
you care about is maximizing the battery charge current.  The discussion
devolved to the flaky open loop method because someone said MPPT was "too
complex" (although it's probably easier).


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