You bring up an important point in solar charging that many overlook. Everyone with Solar power for battery charging should have a charge controller.
Here is a good reference for solar information
http://www.backwoodssolar.com/ The following is a quote from BackWoodsSolar-
CONSTANT-VOLTAGE CHARGE CONTROL, usually 3-stage, is a more precise control to give the most charging possible for the day. BULK charge is first, with power switched straight through from solar modules until battery reaches a preset maximum. ABSORPTION is the second stage charge where the maximum battery voltage is held by reducing the charge current just enough to never exceed the target voltage. Reduced current is done by high speed on and off pulsing, where the controlling "on" time versus the "off" time of each pulse determines the average charge current. FLOAT is a third stage where battery voltage is reduced after charge is complete. This avoids excessive evaporating of battery water and benefits battery life. For those using sealed maintenance-free, AGM or gel type batteries, three stage with float is the only safe method of charge control.
If a person charges the smaller amp hour batteries a charge controller is an absolute must for longer life. Even the Marine and bigger batteries benefit by the regulation of charge.
Once a battery "fries" it is unlikely to be anywhere near it's original capacity again.
I have one 'store bought' controller and 3 others that I built. One of the 3 is for my 24 volt bank, the others are for 12 volt batteries. For anyone wanting the experience of electronic building take a look here
http://www.cirkits.com/scc3/index.html No personal connection to the company, just used some of his ideas for my experimenting.
Either way use of the Charge Controller is important!
