is an MPPT worthwhile?

[gothicsurf]

[font=Helvetica, Arial, sans-serif]I just started a different thread about battery capacity for a modest 2x100W panel solar system connected in parallel.[/font]

[font=Helvetica, Arial, sans-serif]I would like to know if a MPPT would provide any additional power with panels connected in parallel already at a workable charging voltage for a 12V system (17-18V). There is a bunch of hype about how well MPPT track a panel's optimal voltage and would like to know if this could squeeze a few more mAh out of this particular array.[/font]

 

[jimindenver]

I did a simple test for one of my videos. I had two sets of 100 watt panels. One connected to a PWM, the other to a MPPT. Both controllers were connected to one battery so that they were each reacting to the same situation. The battery was my trucks starting battery and I was using the headlights to keep the voltage down , giving the controllers something to do.

The PWM controller was putting out 8 amps to the battery while the MPPT was putting out over 11 amps to the battery at 12 volts. That is well over a 33% increase in power going to the battery with MPPT.

200 watts is not much to start with and MPPT controllers in that range are not expensive anymore. You might as well get as much out of the system as you can.

My test video

 

[Sofisintown]

[font=Helvetica, Arial, sans-serif]I just started a different thread about battery capacity for a modest 2x100W panel solar system connected in parallel.[/font]

[font=Helvetica, Arial, sans-serif]I would like to know if a MPPT would provide any additional power with panels connected in parallel already at a workable charging voltage for a 12V system (17-18V). There is a bunch of hype about how well MPPT track a panel's optimal voltage and would like to know if this could squeeze a few more mAh out of this particular array.[/font]

It's not hype. PMW will draw 12.8 out of the panel because it draws just about your battery's voltage -that's all it can do.
An MPPT will get all 17-18 V out of the panel and charge your battery better / faster.

 

[MikeRuth]

So with that said, I have a Tristar TS45 PWM right now and I'm about to replace my two T-105 Batteries that have served me very well for the last 4.5 years.

Anyone have any thoughts on a 20 amp MPPT? I see several for less than a C note.


Mike R

 

[user 423]

I have a 30A Renogy Wanderer PWM that came with a kit that I've been using since last year. With good sun it gets up to 14.9 volts no problem. I have a roof mounted 100W and an 80W portable (both Renogy). When parked for a while, I'll place the 80W on top of my rear-mounted cargo box and will prop it up this way and that to track the sun.

 

[B and C]

How many amps? That is the real measure.

 

[jimindenver]

Mike

You can get a Rover or epever for under $100 easily. While I looked I noticed that for $100 you can get epever's lastest MPPT which I think would be worth it because the older models are slow to adjust to different situations.

older epever

https://amzn.to/3htWf2u

Rich solar branded Rover

https://amzn.to/32rA8mL

epever's newest

https://amzn.to/3jeWaAc

 

[RvNaut]

Yes.. an MPPT is worthwhile..

This video explains it well...

 

[jonyjoe303]

mppt is only worthwhile on high voltage panels or in your case if you connect your 2x low voltage panels in series to increase the voltage. In parallel a 12 dollar 10 amp pwm controller should do the job. Why spend 100 dollars for no extra benefit.

example that I ran into:

120 watt  (21 volt panel)
pwm = 6 amps
mppt = 6 amps

240 watt (36 volt panel)
pwm = 6 amps
mppt = 12 amps

I've have been able to get up to 15 amps out of 240 watt panel with my ecoworthy 20 amp mppt while charging lifepo4, I max out at about 12 amps with lead acid.

 

[barleyguy]

What time of day was this measured? During the peak part of the day when your 120 watt panel is actually putting out 20 volts, the MPPT should be providing more power. That said, if the power difference over the whole day is minimal, the extra cost might not be worth it. (That of course depends on the person and their budget. I would buy the MPPT anyway personally, because it allows some future expansion.)

I'm using 3x200 watt "12-volt" panels with a VOC (Open Circuit Voltage) around 25 volts, Vmp (real voltage) around 21 volts, and I definitely see a lot more power from MPPT. I own both a Victron MPPT controller and an HQST PWM controller.

 

[Trebor English]

If mppt gives 33% more amps, post #2, that's good.  If you start with one 100 watt panel and spend more you should expect more amps.  A second panel for about the same price as an mppt controller should double the amps, 100% increase.  If you don't want or can't fit a second panel you can use mppt. 

If you have four 100 watt panels, 36 cell "12 volt" mppt is good.  33% of 400 (133) is greater than 100% of 100.

Tiny system, more panel gives more bang for the buck.  Big system, use mppt for more bang for the buck.  The tiny / big boundary goes down with cheaper mppt controllers.  Check again next year.