PSPICE Modeling of Solar Panel and Battery

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Hello All,

How would I go about modeling a lead acid battery and solar panel in
SPICE?

I'm figuring simple voltage sources aren't accurate representations.
When I parallel a 12V source and 14.8V source and probe the shared node
I get 12V. When I swap the values in the sources and probe again I get
14.8V...?!

Any suggestions or sources would begreatly appreciated.

John

 

[Joel Kolstad]

How would I go about modeling a lead acid battery and solar panel in
SPICE?

For the solar panel: http://en.wikipedia.org/wiki/Photovoltaic ... getting the
resistor values correct is not going to be easy without having an actual cell
around to measure, but if you're just doing rough calculations you can make
the shunt resistor infinite (remove it) and the series resistor small (perhaps
around an ohm -- depends highly on how big of a panel you're simulating).

The current source's output is directly proportional to the insolation
("sunshine" ) received.

---Joel

 

[Joel Kolstad]

One other thing... that Wikipedia entry is for a *single cell*, which will get
you about 0.6v -- for a standard 12V panel, you end up with a bunch of single
cells in series. In practice you usually use 24 to get an open-circuit
voltage of around 14.4V -- some partially shaded cells, loading, etc., drops
this; the idea is that you still have a useful 12V output.

See also: http://www.ece.ndsu.nodak.edu/~yuvaraja/scholar team/PV-panels.doc

There's lot of good info on PV out there -- the University of New South Wales
(UNSW) in Australia used to have an on-line course about them, which was
surprisingly good.

---Joel

 

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Joel,

Thanks for the help. I tried fiddling with your info and some other
stuff I found. I didn't have much luck generating meaningful results.

I found a book on Amazon and searched on its title. This website has
the files from the book and looks like it should be informative.

http://esf.upc.es/esf/

I will see what I can deduce from the info....

John