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 purpose these are dinosaurs,but on some old system you still can see a power inverter manufacturers 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 solar inverter manufacturers occasionally,such as discounter and mass marketer offered the very cheap system.