Solar Charge Controllers in Battery Storage Systems

You've most likely heard of solar charge controllers if you have an off-grid or on-grid system or anything involving a solar panel and battery pairing. This handy device is compact yet big on function as it helps ensure your system runs smoothly and provides protection for your main power components. 

Solar charge controllers or regulators are positioned between solar panels and the battery pack to regulate the energy flow and avoid overcharging the battery. Solar charging involves several variables that impact how much power is generated by your solar panels including sunlight exposure and temperature. The solar charge controllers monitor all of these to ensure that optimal power is fed into your battery bank, preventing damage and issues during operation. 

Basically, here are all the functions of charge controllers:

Battery protection

Regulators provide overload protection for batteries since excess current that is higher than what your system can deal with might lead to overheating and eventually to a fire. 

Low voltage protection

Any equipment operating at very low voltages can be dangerous. Thanks to solar charge controllers, non-critical loads are automatically disconnected from the battery once the voltage drops below the recommended level. 

Reverse current prevention

Reverse current happens when your solar panels pump current in the opposite direction instead of one pathway only. This can cause a discharge in your battery, which the charge controller prevents.  

Types of Solar Charge Controllers: MPPT vs. PWM

In terms of charge controller types, Maximum Power Point Tracker (MPPT) and Pulse Width Modulation (PWM) are the most popular ones although MPPT is highly preferred due to overall efficiency, despite its higher price tag. 

Here’s an overview of both charge controllers, how they differ, and their pros & cons.

Maximum Power Point Tracker (MPPT)

MPPT controllers maximise the full battery charging potential of your solar panels. These track and adjust their input according to a system's current, reducing and boosting as necessary. For instance, on a cloudy day, an MPPT regulator will decrease the current drawn in to maintain an ideal voltage level at the output of your solar panel. When the weather becomes sunny, it will go back to drawing more current from your panels once again.  

Pulse Width Modulation (PWM)

PWM regulators are simpler and less expensive. These work by gradually reducing the current to regulate the flow of energy into the battery. Once the power pack is fully charged, it continues to supply a tiny amount of power to maintain the battery charge. PWM controllers are more suited for small-scale applications due to their requirement of having solar panels at the same voltage level as the batteries. 

Sizing Your MPPT Charge Controller

Since battery storage systems are typically a part of large-scale setups, let's focus on MPPT solar charge controllers. Sizing your MPPT controller plays a huge part in the overall efficiency of your system, so it's crucial to ensure it will be able to accommodate the amount of energy your solar panels will generate. 

Check out the factors to consider when sizing your MPPT regulator:

Battery Voltage

When choosing your controller, it's important to make sure it's compatible with your power pack whether you're using a standard 12V battery, a 24V battery or even a 48V one.

Solar Panel Input Voltage

This refers to the maximum input voltage that the controller can accept from your solar panels. It's one of the most important considerations as undersizing your controller can lead to damage and void of warranty. Ideally, at least a solar array of at least 18V is recommended. 

You also need to consider the weather condition since the cold can increase the voltage of your array and base your estimate on the coldest possible temperature during daylight hours. 

Output Current

Your solar charge controller's output is expressed in amps. To determine if a regulator is compatible with your system, divide the wattage of your solar panels by the voltage of your battery pack. For example, if your solar array has 2000W and you're using a 24V battery, your charge controller's rating should at least be 83.3A. 

Get the best solar charge controller for your battery storage system today. At VoltX Energy, all our power plans include a hybrid inverter with a 99% efficiency MPPT solar charge controller function. Multi-purpose, reliable, and convenient, you won’t even have to spend time shopping for a separate controller here - everything you need for your system comes in one high-power package!