[img]http://2.bp..com/-2yRE4A3trYk/VTkDSlyMo7I/AAAAAAAAAfE/KbDv1rUdkDs/s1600/ch.jpg[/img]If you read the Introducing to Solar Charge Controller and you still dont understand the difference between mppt and pmw charge controller, relax this post is for you.
First we to understand how a solar charge controller works.

A normal charge controller (pmw) charges your battery bank at battery voltage irrespective of its rated output.
for example, a 200w panel rated at 32v, The current will be 200/32 =6.25a
6.25a charging a 24v battery bank, you will get
24v*6.25a = 150watts. but your panel is supposed to be 200w, so (200w-150w) you lose 50w on any given day no matter how bright the sun is in the sky. it even gets worse if your battery voltage is low.

Now, lets say you used your inverter heavily overnight and your battery bank voltage dropped to 18v. in the morning your panels will only be outputting:

18v*6.25a = 112.5watts. you lose about 87.5watts! suddenly your 200w panel is only as good as a 100w panel, half what you paid for!

now, with an mppt solar charge controller, the charge controller looks at the output of the panels, and compares it to the battery voltage. it then figures out what is the best power that the panel can put out to charge the battery. it takes this and converts it to best voltage to get the maximum current into the battery. most modern mppt's are around 93-97% efficient in the conversion. you typically get a 20 to 45% power gain in cloudy weather and 10-15% in bright sunlight.


first of all, what is an mppt controller?


an mppt, or maximum power point tracker is an electronic dc to dc converter that optimizes the match between the solar array (pv panels), and the battery bank. to put it simply, it converts a higher voltage dc output from your solar panels down to the lower voltage needed to charge your batteries.

for example using the same 200w solar panel above,

assuming your battery is low, at 24 volts. an mppt controller takes that 32volts at 6.25amps and converts it down, so that what the battery gets is now 8.33 amps at 24 volts. Now you still have almost 200 watts, your money's worth.

24v*8.33 = 199.92 approx 200w.

assume your battery bank voltage is low, it even gets better:

18v*11.1 = 199.8 approx 200w

where with a normal charge controller you lose power the lower you batter voltage,
with an mppt charge controller, you get more current and your panel's rated power
when you need it most.

http://www.charpell.com/2015/04/a-laymans-defination-on-pmw-and-mppt.html