The comment below is valid if there are only solar panels involved.
However ,when these are used in combination with a wind generator a current
dump is required.
My battery operated station has its batteries charged by this combination of
sources.
The home brew charger comprises a zener referenced comparator ( 741 opamp)
driving a number of power transistors ,with the rest of the load being a
number of car head light bulbs.
When the batteries are fully charged ,all current generated is dumped .its
resulting heat making a minor contribution to shack heating.

Frank GM0CSZ / KN6WH

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It's not necessary to provide a "dump" for a charge controller when a
solar panel is used for charging (at least the ones we use at work don't
require a dump). It appears the charge controller shorts the "array"
connections and the panels circulate their "short circuit current" around
the array loop.

Scott
N0EDV


The only two times I've had to use some kind of "charge controller"
were when the sourse was a:
* wind generator - when the wind blew, it created whatever voltage
was necessary to force about 15 amps into whatever was connected!
(I used a zener and a few transistors -- two of them big! -- to
"dump" excess current into two 100-watt 1-ohm resistors.
* solar panel - except that my panel only produced about 2 amps in
bright sunlight, the sun shown much more often than the wind blew,
so this was basically the same problem: dump excess current.

Incidentally, for not-too-big DC power supplies, I've not found it
particularly necessary for them to be very "pure" DC; a 60-amp-hour
car battery acts like a pretty-big filter capacitor!

--Myron, W0PBV.