Charge Controllers 101
Over-charging a battery can lead to battery and solar panel damage, because once the battery is full, without a charge controller the electrical current can go back into the solar panel causing major damage to components. The picture above shows a morningstar sunkeeper charge controller which is a basic controller that does a great job regulating the electric current that comes from a solar panel into a battery.
Charge controllers come in different voltages, for example the sunkeeper comes in a 12v or 24v….your charge controller has to match the voltage your solar panel puts out and how you have your batteries wired up. If you have a 12v solar panel, you would need a 12v charge controller and wire your batteries up in a 12v series.
Even though most residential systems do not have a batteries and will never need a charge controller, those people who are working on off-grid systems or are building the next solar powered car, lawn mower or are trying to retro fit solar panels onto your devices, you need to understand why charge controllers are important.