The charge controller in your solar installation sits between the energy source (solar panels) and storage (batteries). Charge controllers prevent your batteries from being overcharged by limiting the amount and rat. Regarding “what does a solar charge controller do”, most charge controllers has a charge current passing through a semiconductor which acts like a valve a to control the curre. Typically, yes. You don't need a charge controller with small 1 to 5 watt panels that you might use to charge a mobile device or to power a single light. If a panel puts out 2 watts or less for. There are two main types of charge controllers to consider: the cheaper, but less efficient Pulse Width Modulation (PWM) charge controllers and the highly efficient Maximu. When it comes to charge controller sizing, you have to take into consideration whether you're using a PWM or MPPT controller. An improperly selected charge controller may result in up to a 5.