Have you ever worn an undersized or oversized shoe? If they are too loose, you may get blisters where your shoes rub against your skin and tight shoes can even cause more problems. Let’s look at our charge controllers like our shoes; if they don’t fit, you most likely won’t enjoy your solar journey.
A solar charge controller regulates the current flowing from the solar panel into the battery bank to avoid overcharging the batteries.
It is therefore very necessary that you make use of a charge controller that fits, each time you’re designing your solar system. This way you you’re guaranteed of getting sufficient energy from your solar panels to charge the batteries. Also, you would successfully protect your battery from overcharging or undercharging. Charge controllers come in two different forms:
- Maximum Power Point Tracking (MPPT): This harvests maximum power from the solar array and is generally more expensive.
- Pulse Width Modulation (PWM): This works by slowly reducing the amount of power going into your battery as it approaches capacity. This is a good low cost option for solar systems.
Charge controllers are rated in Amps and Voltage. For instance, you would notice labels such as 60A 12/24v, 80A 12/24v on charge controllers.
How is this determined? Do I just choose any size or voltage rating of charge controller?
There are two key factors to consider.
First is the voltage selection. Always make sure the charge controller and your system voltage are compatible – the standard configurations are 12volts, 24volts 48volts etc. What this means is that if you are wiring a 12volt battery, you need a rated 12volt charge controller.
Next is to go for a charge controller efficient enough to handle the maximum output current from the solar panels array and determine the right Amp size. Here is a simple DIY formula to determine what ampere is right.
Watt of panel × number of panels = Minimum amps charge controller needed
DC Voltage of Inverter
Say for example, you need to know the minimum amps charge controller needed for your 1.5kva 48volt system using four units (4) of 300watts solar panels array. Going by the above formula,
300 × 4 = 50 (amps minimum needed)
So, the closest rating of charge controller you should consider is 60A/48v. This is only a beginners’ guide to choosing the right charge controller for different solar system sizes. If you have more questions on this, feel free to speak to a Kartel solar expert now.