There are 2 main solar charge controllers for solar street lights. These are the PWM and MPPT. The technologies of both are normally used for off-grid solar power. Both of them are a good option when we talk about charging the battery efficiently.
Now, in order to understand which social charge controller is better, one needs to know which type of work the controller is well-suited for.
If you want to choose between the two controllers, you need to understand the power curve of PV panels. It is vital due to the fact that it shows you the power generation which can be expected based on the combined current and voltage generated by your PV panel. The ratio which should be ideal is one which produces the most power and is known as the Maximum Power Point or MPPT for short. The changes greatly depend on the irradiation situation throughout the day.
PWM (Pulse-Width Modulation)
The Pulse-Width Modulation or PWM for short is important when we talk about the battery bank and when it is full. As the battery charges, the solar charge controller allows as much current as can be generated by the PV panel so as to achieve the target voltage for the charge stage.
Once the battery achieves its target voltage, the controller would automatically switch from the battery banks to the panel array; hence the battery bank would be disconnected. This helps regulate the voltage of the battery and allows it to be constant.
The swift change method is what is called the PWM. It allows the battery bank to be charged while at the same time ensuring that the battery does not get overcharged during the process. The thing with the PWM controller is that it would normally operate a little over the maximum power point.
MPPT (Maximum Power Point Tracking)
The Maximum Power Point Track or MPPT for short helps provide an indirect connection for the PV array and the battery bank. The indirect connection includes DC voltage converter which would take the extra PV voltage and transform it into additional current when there is a lower voltage without losing power.
The reason why the MPPT is able to do this is due to the fact that it has an adaptive algorithm which follows the PV array and then simply adjusts the increase in voltage to ensure that the most efficient level of power is maintained for the system. Thus, the controller is highly efficient.
Which One is better?
If you want to choose a controller between the two, you need to keep a few factors in mind such as the size of the array, site conditions, load, cost of the solar power system and the system components. Each of these factors plays a huge role in determining which controller is the best fit for you. Understand the factors beforehand in order to make the right decision when choosing a controller.