Solar charge collectors
A charge regulator is actually the same as the voltage regulator in a car. Another word for charge regulator is the charge controller. It regulates the current and voltage from the solar cells going to a battery. The voltage of most solar panels varies at time. If there would be no regulation then the batteries will be overcharged and got damaged.Most people say you don't need a controller if the panels puts out about 1/60th or less every day of the battery capacity. You also don't need a solar charge controller if you have a small maintenance or trickle charge panels.
Indicators
Most of the controllers have some indicator: A simple LED, digital meters or a series of LED's. Newer charge controllers have a built in computer interface for monitoring and control. The simple ones only show that you have power or not and if you are getting some kind of charge. But the majority of the solar charge controllers will show both the current and voltage coming from the panels and the voltage of the battery. Some controllers even show ho much current is being pulled from the LOAD terminals.
Controls
There are the simple one or two stage controls; they rely on shunt transistors on relays to control the voltage in 1 or 2 steps. They just disconnect or short the solar energy panel when a specific voltage is reached. They are known because of their reliability, there is not much to break and they have so few components.