Consider using a faster switching chip -- this reduces the amount of
inductance you need to store energy.

There are multiple losses here.
MY nominal array voltage is about 7V my converter is boosting to
10 to 20 V (Depends on the amount of solar power availible and the
loading conditions on the prop/motor)

So if I run a normal boost converter with a good Shotkey diode I get a
drop of 0.4V or 4% (at 10V) of my total power goes into the diode
drop. So I am using syncronous rectification.
I can't find a highside fet driver that will efficently run much
faster than 100Khz.

I've thought about (mis) using one of the low voltage syncronous
buck converters and running it backwards, but the the chips are
generally too smart about startup and the error conditions and current
sense choices are wrong.



Paul (Kl7JG/6)