Note that single junction Silicon solar cells produce 0.4-0.5V and you would
need at least two in series to give enough output voltage to start the
converter. The neat part of the circuit is the bootstrapped first stage
converter. It receives its supply voltage from its own output.

There was some recent discussion about problems of adding solar cells in
series. The main problem is that the weakest solar cell in series (or one
that is shaded) limits the total current. Reverse shottky diodes across the
cells can bypass shaded cells. Similar problems occur when paralleling
solar cells. In that case the shaded cell may act as a short circuit to the
output of its more active neighbors.

wilf

-----Original Message-----
From: Richard Piotter
To: BEAM
Sent: 2/10/02 10:04 PM
Subject: [beam] 5 volts from .8 volt solar panel

It's a little complex, but it might just be useful to someone here. It's
more for high current, low voltage cells, however, if someone ever sees
such cells for cheap, they might be able to use something like this to
draw a reasonable voltage from it. It requires a pair of inductors
however, and those can often times be a pain to find. The chips are
likely "samplable" from MAXIM, and most of the other parts are common.

I think this would be more suited to a larger solar project (large low
voltage, but high current solar panels on a largish solar bot), but
still there might be someone out there interested.

For small bots, a voltage doubler like has been posted in the past is
likely all you'll ever need.

http://dbserv.maxim-ic.com/appnotes.cfm?appnote_number=188
--

Richfiles
richfiles@...
http://richfiles.calc.org


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