Advantages of PWM solar controller | Disadvantages of PWM solar controller
This page covers advantages and disadvantages of PWM solar Charge controller. It mentions benefits or advantages of PWM solar controller and drawbacks or disadvantages of PWM solar controller.
There are two types of solar charge controllers viz. PWM and MPPT. These charge controllers are designed to regulate flow of current to the battery from solar panel or array. The main functions are to prevent battery from over-charge and to prevent it from deep discharge.
What is PWM solar controller ?
PWM stands for Pulse Width Modulation or Pulse Duration Modulation. It functions as electronic switch. In this method average value of voltage (or current) fed to load is controlled by a switch. It turns ON and OFF between supply and load based on battery charging status.
During normal charging period, PWM controller delivers as much current as required from Solar PV panel to the battery. When battery reaches target voltage, PWM charge controller disconnects battery from PV panel to prevent it from over-charging.
Voltage output from PWM generator can be calculated as per following equation.
Vout = Vmax * Duty cycle (%)
Where, Duty Cycle (%) = [ TON/(TON+TOFF) ]*100
Here, TON + TOFF = period of the pulse width modulated waveform which is equal to 1/Frequency.
PWM charge controller operates close to maximum power point but often slightly above it as shown in the figure-1. PWM controllers are available at cheaper rate and in smaller sizes. The low pass filters (usually RC type) are used to convert the PWM output to desired DC voltage. Due to less electronic components in its design, PWM controller has longer lifespan. All the latest microcontrollers are available with PWM feature which makes it easy to develop PWM solar charge controller. Refer difference between PWM and MPPT >> solar charge controllers.
The figure-2 depicts PWM solar charge controller.
Following are the typical specifications of Luminous PWM solar charge controller.
• Model : SCC1220NM , 20 Amp.
• Automatic selection of 12V/24V battery
• Efficiency : 98%
• Microcontroller used for software based protections
• Option to select SMF and lead acid battery
Benefits or advantages of PWM solar controller
Following are the benefits or advantages of PWM solar controller:
➨It is cheaper compare to MPPT solar charge controller.
➨It is smaller in size and hence easy to handle.
➨It offers longer lifespan due to fewer electronic components and less thermal stress.
➨It is ideal for smaller systems where there is less difference between solar panel output and battery voltage.
Drawbacks or disadvantages of PWM solar controller
Following are the drawbacks or disadvantages of PWM solar controller:
➨It is less efficient than MPPT solar controller.
➨It generates less output and hence supports less capacity in Amp.
➨It can not optimize for voltage differences and there is no load optimization.
➨It can not be used for larger systems and in situation where solar panel output is substantially greater than battery voltage.
Also refer advantages and disadvantages of Solar Electricity at home.