A charge controller is used in combination with a battery, and it does just what its name implies: it controls the charge your battery is receiving. The charge controller is placed between your solar module and the battery.
When the battery has received enough charge, the charge controller will withhold further charging. This is also called "voltage regulating" within the solar industry.
Without a charge controller, your battery will over-charge. This can damage your battery and it may be dangerous in other ways-it can even cause fires.
Want to learn more about charge controller features?
Some charge controllers include maximum power point tracking (MPPT). This feature optimizes the solar photovoltaic array's energy production. This can be part of the charge controllers' use of set points — specific voltages at which the charge controller changes its charge rate. Some charge controllers allow you to adjust these set points yourself.
Most charge-controllers also include a feature called low-voltage disconnect (LVD).
This feature prevents the battery from over-discharging. As with any other battery, draining causes damage. Almost all modern inverters, even cheap pocket-sized ones, have this feature built in.
And finally, charge controllers offer battery temperature compensation (BTC). With this feature, the charge controller adjusts the charge rate based on the basis of the temperature of the battery. Batteries are sensitive to temperature variations above or below 75 F.
If you're interested, we can tell you more about batteries and how they work.