PWM vs MPPT Controllers

[Jacksonricher]

What is the difference between these two type of controllers? Should I use a different controller?

(I am getting Renogy 2x100w Monocrystiline panels kit, comes with PWM Wonderer controller. I plan on adding two more panels in the next six months totaling 400w)

 

[Trebor English]

Mppt controllers cost more than pwm.  They can cause more battery charging to happen.  On really small systems like my one panel 100 watt system I can buy a second panel for $100 and double my electric supply.  An mppt controller might be a similar price but only give a 20% increase.  If I already had 5 panels a 20% increase would be the same as another whole panel.  Bigger systems benefit from mppt more.  

There are other considerations.  If you are out of roof space and you can't add another panel mppt may be your only choice.  If a particular controller has a user interface you like, nothing else will do.  A very expensive pwm is not a bargain like a cheap one.  Some controllers need a smarter user to keep batteries longer, some are more idiot resistant, none are idiot proof.  

They say you get what you pay for when they mean you have to pay more to get more.  Just because you pay more doesn't mean you will get more.  It only means you paid more.

Opinions are like body parts.  Everybody has some parts.  I like the cheap under $15 pwm.  I like it because I didn't pay more and it works for me.  

In your case, you are getting that kit controller.  Don't buy another controller.  Use the one you already bought.  It should work.  If you need more electricity you then have a different puzzle.

 

[Canine]

I need way more information to figure out if you should use a different controller. Will the panels be connected is series, or parallel, or series/parallel? Are you charging FLA, AGM, GEL, or Lithium? If you want to get the most out of your panels, use a controller for each panel and get charge controllers that can be networked which means MPPT. If you think you might change the panels in the future, that would be another issue. Lots of things to consider.

 

[Spaceman Spiff]

I agree with Trebor English:  You are paying for a charge controller, use it.  When you get another two 100W panels in 6 months you can then re-evaluate.  With this CC you will need to wire your panels in parallel.

I have 2X100W Renogy panels (wired in parallel), a PWM controller, 208AH of batteries and am vey happy with my system.

 

[jonyjoe303]

for 21 volt panels get pwm, for 36 volt panels get mppt. If you run 2x 21 volt panels in series (total 42 volts) you can use mppt. Mppt requires high voltage panels to get extra amps produced. You can use mppt on low voltage panels but it won't give you any advantage.

This is some of my "actual use" results with different panels/ controllers.

kycyora 120 watt 21 volt panel
pwm controller = 6 amps
mppt controller = 6 amps

sharp 240 watt 36 volt panel
pwm = 7 amps
mppt = 12 amps 

If you have 200 watts in panels, the max amps you can get is 13.8 amps (200watts /14.4 volts), thats in the best conditions. In my situation, (240 watts/14.4 volts) the best I can get is 16.6 amps. But the most I see is 15 amps when charging a depleted lithium and the sun is overhead, but thats rare.

With 200 watts you should at least get 10 amps when the sun is overhead.

 

[jimindenver]

On a 200 watt system a PWM controller can produce 8 amps when the battery voltage is low. A MPPT controller will produce over 11 amps at the same time. More power pure and simple. Kept at that level it is enough extra power to recharge the smallest marine battery on a summers day.



The are other things to consider are will you be getting identical panels to add. PWM does not care if the panels are all matched.

A big thing is that either type of controller can be set to properly charge your batteries. I would pick a PWM that could be set properly over a MPPT that could not. The PWM will make sure the batteries get charged if not slower. (actually I would pick a MPPT that could be set properly)

I would suggest setting your system up as is and seeing what it does for you. Then decide if you need more panel, a better controller or both.

 

[regis101]

I consider myself a novice. I've spent many hours reading and well as asking questions within these pages.
Use the search function. Hundreds of hours of info.

I chose the MPPT route with 200w because I am able to have the panels in series or parallel depending mostly on location from the CC/Batteries. Kinda like having the best of both worlds. The present batteries are two 55ah AGM's. I like keeping the 2:1 ratio.

The panels are used as portable at a distance of ~50' from the van with 12awg wiring since I park in the shade and have fun chasing the sun. So having the higher voltage is my friend.

In the end, watts is watts. Getting it from the panels to the batteries is the key.