What is a charge controller?
A charge controller (or regulator, as they're also known) regulates the flow of electricity to or from a battery storage system attached to your solar or wind setup. This prevents overcharging which can reduce the battery’s lifespan, and power leakage which can drain a battery dry. In solar arrays and with wind turbine setups, the charge controller plays an important role in shutting off storage systems when they’ve reached capacity or stopping all the power from completely flowing out of your batteries.
How do charge controllers work?
When a storage battery connected to an array has reached a set high voltage level, the charge controller kicks in and shuts off any further power from being fed to the battery. The charge controller monitors the voltage, and restores the flow when the battery drops back down below that level. More modern charge control technologies allow for storage levels to be adjusted, and will monitor battery temperatures to prevent them from overheating.
How are charge controllers installed?
Charge controllers are often sold as a component of a solar or wind turbine kit, and are usually connected for you as part of the standard installation. The device will by necessity be connected close to the battery, so this will generally be located inside your home or in the garage. When the battery's full, the power diverted from it needs to go somewhere, so this is usually split off into a large ‘always on’ type of device, such as an electric water heater. This is known as a ‘shunt load’.
What types of charge controllers exist?
While the basic principle of the charge controller is common to all types, variations exist in the extra features that are available, displays to provide information such as charge level and temperature, manual controls and so on.
Another variation point is capacity; you’ll need to make sure the device can regulate for the size of the battery you’re connecting it to, but since most regulators are sold as part of a kit this will have already been taken into account. If you’re planning on expanding your array or storage capacity in future, you might want to consider this when choosing your regulator.
What to look for in a charge controller
In a nutshell, more features and high efficiency. The more efficient your regulator is, the more efficient your whole system will be. If your regulator is cutting off too early, it won’t matter if your panels are super-efficient as they'll only be providing a percentage of the total charge to the battery.