What the difference is, and why you should choose an MPPT or a PWM type Solar Controller for your system.
A solar charge controller is needed in virtually all solar power systems that utilize batteries. The job of the solar charge controller is to regulate the power going from the solar panels to the batteries. Overcharging batteries will at the least significantly reduce battery life and at worst damage the batteries to the point that they are unusable.
Let's be clear what each thing means. PWM is pulse width modulation and is a way of turning something on and off usually very rapidly and electronically. What such a switching action does is entirely different - there are a number of uses electronically that use PWM, in general to regulate power flow from a low impedance source into a finite impedance load. MPPT is a class of algorithms that attempt to maximise the power transfer from a source with finite impedance to a load usually with finite impedance - in other words to perform an impedance matching operation (maximum power transfer occurs when source impedance = load impedance). This could involve a PWM circuit though really what is going on here is switching power in and out of reactances (usually inductors) to perform the impedance conversion. The source impedance of a solar array depends on the load, and this requires some sort of adaptive control to keep the operating point at optimum. This control is the MPPT.
as for MPPT, it is better to optimize the power generation for getting the highest possible amount of power. It is basically tracking the sun, so they work based on sun radiance. But if you need the solar PV for small usage (let's say 1 PV only), then MPPT is too much for you. You can read our paper for reference:
http://isomase.org/IJERCE/Vol.7%20Jul%202017/7-2.pdf
hundreds of papers are published and nearly PWM is phased out
1- mppt harnesses about 30% more power from panels.
2- mppt has dc-dc converter charging batteries from low irradiance.
3- can accept higher voltage as input >> less power loss in cables.
and more
so never buy a PWM even though it is 3 times cheaper
Let's be clear what each thing means. PWM is pulse width modulation and is a way of turning something on and off usually very rapidly and electronically. What such a switching action does is entirely different - there are a number of uses electronically that use PWM, in general to regulate power flow from a low impedance source into a finite impedance load. MPPT is a class of algorithms that attempt to maximise the power transfer from a source with finite impedance to a load usually with finite impedance - in other words to perform an impedance matching operation (maximum power transfer occurs when source impedance = load impedance). This could involve a PWM circuit though really what is going on here is switching power in and out of reactances (usually inductors) to perform the impedance conversion. The source impedance of a solar array depends on the load, and this requires some sort of adaptive control to keep the operating point at optimum. This control is the MPPT.
Tony Maine@ Thanks for giving valuable and accurate information showing the difference between the two techniques.
Dear Ameer,
I agree fully with Tony. The ambiguity comes from using the DC/DC converter to match a specific load to the maximum power point of the PV generator by adjusting the controlling pulse width power switch in the converter.
This is just a comment which may help to complete the picture.
Best wishes
Dear Ameer L.Saleh
MPPT Solar controller:
Forceing the PV panel to generate its maximum possible power whatever the Load resistance varies or weather conditions (Solar irradiance /Temperature ) varies with time. That is by instantaneously adapting the duty cycle of the converter (which means adapting the operating point of the system).
PWM Solar controller:
It Forces the PV panel to generate power exactly As Mr Tony Maine said: 'to regulate power flow from a low impedance source into a finite impedance load' (duty cycle of the PWM will be involved in R load hence change R load value) but not necessarily maximum power. In addition, PWM will allow you to maintain your output voltage in your desired value.
However, this technique does not guarantee generation of maximum possible power or even track for MPP it just changes the resistance seen by the source into another constant value.
Good luck.
There are very few losses in mppt solar controller compared with pwm
in few words: MPPT is used to generate the PWM signal for the DC-DC converter, based on the old values of P and V or I, the MPPT algorithms generates the corresponding PWM signal
The (MPPT) method is more efficient, cost-effective and useful than the (PWM) method.
The PWM is a way of switching in the inverter and converters. The MPPT is used to make an impedance matching between the load and source to make the losses as minimum as possible and maximize the power transfer.
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