Solar charge controller come in 3 general type

The voltage in one or two step is control by relays or shunt transistor for simple 1 or 2 stage solar controller. when a certain voltage is reached it will essentially just short or disconnect the solar panel.For every practical solar controller suppliers purpose these are dinosaurs,but on some old system you still can see a few-and some of the sixpenny ones for sale on the internet.Their only real claim to fame is their dependability-and so few components inside,there is not much to break.

PWM and/or stage such HANFONG,WINIVERSAL,GAMATONG,and many other.These are very good for the industry standard now,but you will still see some of the older relays/shunt type around in occasionally,such as discounter and charge controller suppliers mass marketer offered the very cheap system.

http://hanfong.npage.de/