One of the most important parts of a solar energy system is the charge controller as it enables all other parts to work together. Understanding how a charge controller works is important for figuring out how much your off-grid solar energy needs. Solar panels with 20 watts or more usually can’t be directly connected to loads because the voltages they produce aren’t compatible with most equipment and batteries. Obviously, a 12V load isn’t ideal when you have a 24 or 48V solar array, which is where charge controllers come into play.
But why can’t they just make solar panels that produce 12V? Well, simply because the output of solar panels depends on a couple of factors, such as light and temperature. That being said, the output of the solar panels will vary, which is why you need a charge controller 12V. The controller basically ensures a consistent flow of energy output from your batteries. There are two basic charge controller 12V types – PWM and MPPT.
PWM charge controllers are the most affordable and common type. They’re typically referred to as DC-DC converters, which is incorrect, as they are switches similar to switching power supplies that match the solar panel output to the load voltage. This technology has been around for quite a while, and is quite outdated, so they won’t use the full capacity of the solar panels, resulting in a loss of power. These controllers are the most popular choice just because they’re the most affordable ones.
MPPT solar controllers, on the other hand, do much more than act as a switching circuit that regulates voltage output. These devices have onboard computers that control a system of semiconductors and gates which convert DC current to high-frequency AC current then back to DC current. As the amount of energy that goes into the panels shifts, the controller adjusts in real time. MPPT solar controllers usually operate with 90%+ efficiency.
However, there are also drawbacks to MPPT solar controllers. For starters, they’re more expensive, and usually, cost twice the price of a PWM controller. If your solar panel capacity doesn’t exceed 350 watts, then you probably don’t need an MPPT charge controller. Furthermore, MPPT controllers aren’t as mechanically robust as PWM controllers. This is due to the fact that they’re composed of computers with circuit boards, as well as tiny mount components. They’re meant to be mounted indoors where there’s some level of climate control.