Sorry for nit-picking but how does one really know the output capabilty of the
panels vs the storage capacity of the battery? True, you can place an ammeter
across the panel to determine the dynamic current, and spec the battery to
exceed the panel, but that's a lot of guessing and fine tuning, and also the
capacity of the battery will diminish over its lifetime that will eventually
become lower than the panel output and of course, the no-load voltage will
start to rise over the batteries 100% S.O.C. where the panel will start cooking
the battery. Also, the whole idea of charging in a reasonable time (including
overcast skies) means having a panel output somewhat larger than the battery.
Any seconday storage cell doesn't like to remain lower than 80% S.O.C. and will
die sooner than anticipated.

I am currently working on a low cost (low parts count) highly efficient
switching regulator, that will satisfy most users needs and will post results
and plans for building such, on my website:
http://www.Vvalley.com/solar
This is kind of a newbie site for beginners but I have a lot of new stuff to
post. The site is a little old and I'm updating links as I post this msg.

Thanks for your time to read this post.

Rick

Olin Lathrop wrote:

> > Note of caution:
> > Normal silicon solar cells (panels) CANNOT be connected directly to a
> battery
> > without diode isolation, preferably a schottky diode for lower voltage
> drop. In
> > darkness they will suck the life out of the battery.
>
> Yes, sorry I forgot to mention that in my post.
>
> > Even though the output
> > of small panels won't necessarily "cook" the battery, some sort of
> regulation
> > should be designed into the circuit as just plain good engineering.
>
> I don't see the point if the solar cells can't produce more current at full
> battery level in full sunlight than the batteries can withstand
> indefinitely.
>
> ********************************************************************
> Olin Lathrop, embedded systems consultant in Littleton Massachusetts
> (978) 742-9014, olin@embedinc.com, http://www.embedinc.com
>
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