[MLB-WIRELESS] Cray---zeeee idea.

[Ben Anderson]

> I'm told Canon Unisolar provide the best performance in terms of
> charge/day/dollar, as they have the best performance under low light
> and partially shaded conditions, thus more useful hours per day.  i
> believe they are amorphous silicon, as opposed to the crystalline
> silicon in other cells.
>
> >Dick Smith had 1V, 250mA panels for sale that are very small ($4.10 each
or
> >something).
> >16 of these provides 16V @ 4A peak,
>
> umm, i think you can *either* add the voltage (serial) *or* the
> current (parallel)
>
> i'm a bit rusty on this.

P = VI
(power = voltage x current)
so therefore VI = VI
So therefore 1V, 250MA (suitably 'transformed') = 2v 125ma, or 1/2v 500ma
(or any ratio that the product remains at 0.25W)

Just to say it explicitly, if you add modules in series, the voltage
increases, and current stays the same.  Add them in parallel, current
increases, voltage stays the same.  Power (energy) must be conserved!
There's no free lunch (though if someone wants to shout me, I'll eat ;)

Just in case you still don't get it, here's another way...
the 1v 250ma cells (p=vi) are 250mw.  If we have 16 of these, we've got
4watts.  Now back into p=vi, we can have just about any ratio of V and I
that multiply to 4 and we're not 'cheating' the system.
hehe, to get the 16V at 4A, one would need 16x16 (ie 256!! modules -- 1049$
at the price from dick smith -- more than the cost of a fully ready-made
panel!)

Ben.


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