Solar Charging and Amp Hours

DarkSkySeeker wrote:
Is the amperage from a solar panel constant as the battery it is charging charges up?

I.e., as your battery reaches full charge, the current drops to zero either via the charge controller or the equalization of the panel and battery, right?

So this simple math is false? 120 watt panel, 12 volt system, 10 amps, 10 hours to charge a 100 Amp Hour battery?

False in many ways :(

The current to battery rises from first light to high noon (when the panel output is as high as it can get with the sun that high--which is not necessarily the most the panel could do if the sun were higher at that time of year in that place-- and then it goes back down till dark as the sun's angle gets less direct again.

So no constant amps as the battery charges up.

With PWM, the "panel voltage" is the battery voltage--they do not eventually equalize. Current output is iaw the IV curves for that panel--see the specs for any panel for its IV curves.

As the battery nears full charge, its amps acceptance rate tapers as usual, so whatever the solar output is by then, amps will taper. Now you might see 'extra amps' that can be used to run loads without stealing any from battery charging.

To learn what AH haul a panel can provide, there are tables on line for locations and times of year that give "insolation" figures. Use those with the panel specs.