UPDATE--results with MPPT posted 1 June.Got a chance to run this test today with no clouds but a slight haze up high so not quite 1000 insolation, showed as 8.93Isc vs rated 9.0, however that did not affect the tests as such. 255w panel tracking aimed at sun.Started with the 458AH bank disconnected from rig ( it was running on a spare 12v meanwhile) at approx. 75% SOC (very approx.!) at 25.4 volts. panel Voc 35.2, 46C , Isc 7.6Using the Solar30 PWM controller set to 30.0 volts Vabs:0845- 25.7v x 7.3a = 188w0945- 26.5v x 8.1a = 215w1115- 27.4v x 8.1a = 222w1215- 28.9v x 7.6a = 220w1230- 29.5v x 7.2a = 212w1245- 30.0v x 6.8a = 204wSo yes, a 60 cell panel can get the batts to 30 volts no sweat.You can see the amps started to taper towards the end with SOC maybe 92% or so. Could be a touch of IV curve drop in I above 28v in there too. -------------While at it, I swapped over to the Eco-Worthy MPPT with bank at 24v1115- 27.4v x 8.0 = 219w compares with PWM at 1115 above.So as with the first test of MPPT vs PWM at 24-24 I did with my old 230w panel, they come out nearly equal for amps to the battery at 45C panel temp.One new thing I have not figured out yet is that the PWM controller was not passing through the actual panel Isc as taken disconnected, but something less than that. eg, Isc 7.6a, vs 7.3a to battery, and 8.2 vs 8.0 etc. The IV curves don't show that much drop in I so the controller must be eating some. Not sure--needs more study :)I was hoping with a rated 9.0 Isc, I would get that to the battery with PWM in 24v mode, which would be like 18a in 12v mode, but it looks like this won't quite happen. When I do the hot panel tests this summer, I will check on that some more.

Are the cc's overheating a little, perhaps? Are they well ventilated?How do your solar30 and eco-w numbers compare to jimindenver's, and others'?

I've never done a 24v test with my Eco-w's. Also at 12v the much dryer air and altitude make for a lop sided test in my opinion. That said, my 250w panels easily hit 18.5a and 226w. In series they are a bit less impressive at 48a and 660w.If BFL had a "respectable" controller he could run both of his panels in series against the two in parallel on the 30 to see if a higher voltage would give the MPPT something to work with. :PIt looks like I wont be getting any more comparison test in with the Eco-w and Schott 230w. I never updated the ad but someone wants to buy it this weekend and I wont have sun until Sunday. Oh well, I need batteries more than test. lol

Jim, thanks for the tests you already did, showing the Eco-W gets as many amps out as the fancy controller. The fancy features are what is being paid extra for, not for more amps.The controllers were at ambient 20C in a light breeze off the sea, so no overheating issues. The panel and controllers are performing to spec.It does look like there is still a small penalty in the MPPT buck conversion, which the PWM doesn't have but it is tiny. So 24-24 if you already have a 12/24 controller, either type will do the job.

and the purpose of this test ?to show that you can get a 24v bank to 30v for equalizing ?you enjoy tinkering around with batteries .. way too muchthere is a bit of the "Mad Scientist" in you

Any time your convert something there is a loss to be dealt with. At least the loss is the same between my two controllers. It was pleasing to see the Eco-w could keep up with the MS. I still think it and a 24v panel make a quick, clean, inexpensive set up if it meets the need.

60 Cell Panel vs 24v Bank MPPT and PWM UPDATE | Good Sam Community

30 Replies

JiminDenver
Explorer II
Jun 01, 2015
One more thing. The only time I tested the voltage across the terminals on the Eco-w was in the 250w vs 245w. The 250w was running 33v and 18a in bright light, 29v and 5.69a at a bad angle. The optimal Vmp may be what it is rated for but the true Vmp can be anything under the Voc. That leaves head room for a 255w panel in bright light.
BFL13
Explorer II
Jun 01, 2015
Salvo wrote:
Hey, keep emotions out of it. And stop being a cry baby!

If there isn't adequate voltage headroom the controller won't output any current in mppt mode. But that doesn't mean you can't get production out of the controller. The controller switches to pwm mode.

You haven't proven the controller is operating in mppt mode. Just stating it's in boost mode doesn't cut it.

BFL13 wrote:

Salvo, you are being a real PITA about this. You first said it was the Vmp that would prevent any amps, but now that you can see the controller finds higher Vmps to keep the amps coming, you are still arguing!

The results are the results! If you don't like them get your own results or get somebody else besides me to get some and see if you like those any better!

Gee whiz!

The instant it went from Bulk to Float, "panel voltage" went from 31 (near Vmp) ( as it had been steadily since being 29v) to 35 (near Voc same as with PWM). You can interpret it all you like. That's what happened.
JiminDenver
Explorer II
Jun 01, 2015
Remember the controller uses PWM to charge with all of the time. The buck converter is always taking whatever the panel provides and turning it into a wash that the controller decides what to create and feeds that to the PWM. I believe it does this by adjusting the voltage of the output of the bulk converter to what the battery needs and the amps available at that voltage is what you get.

In absorb and float the controller is holding a voltage and there is no need for MPPT. That doesn't mean the bulk converter is going off line or I wouldn't see 45a out of my three panels in series running at 102 Voc with an array current of 10a. It's nice knowing my batteries are still being charged while I run the air conditioner.
Salvo
Explorer
Jun 01, 2015
Hey, keep emotions out of it. And stop being a cry baby!

If there isn't adequate voltage headroom the controller won't output any current in mppt mode. But that doesn't mean you can't get production out of the controller. The controller switches to pwm mode.

You haven't proven the controller is operating in mppt mode. Just stating it's in boost mode doesn't cut it.

BFL13 wrote:

Salvo, you are being a real PITA about this. You first said it was the Vmp that would prevent any amps, but now that you can see the controller finds higher Vmps to keep the amps coming, you are still arguing!

The results are the results! If you don't like them get your own results or get somebody else besides me to get some and see if you like those any better!

Gee whiz!
BFL13
Explorer II
Jun 01, 2015
Salvo wrote:
We just got through discussing this. If there's not enough voltage headroom, the controller will switch to pwm during bulk mode.

At 800W/m^2, Vmp =25V.

BFL13 wrote:

Easy, it is only in MPPT during Bulk and it said it was in Bulk and rated Vmp is 30.2 and it was doing around that going from 29 to 31 during the run.

Salvo, you are being a real PITA about this. You first said it was the Vmp that would prevent any amps, but now that you can see the controller finds higher Vmps to keep the amps coming, you are still arguing!

The results are the results! If you don't like them get your own results or get somebody else besides me to get some and see if you like those any better!

Gee whiz!
Salvo
Explorer
Jun 01, 2015
We just got through discussing this. If there's not enough voltage headroom, the controller will switch to pwm during bulk mode.

At 800W/m^2, Vmp =25V.

BFL13 wrote:

Easy, it is only in MPPT during Bulk and it said it was in Bulk and rated Vmp is 30.2 and it was doing around that going from 29 to 31 during the run.
BFL13
Explorer II
Jun 01, 2015
Salvo wrote:
How do you know the controller is in mppt mode and not pwm? In pwm mode the controller has at least 1V drop.

..........

Easy, it is only in MPPT during Bulk and it said it was in Bulk and rated Vmp is 30.2 and it was doing around that going from 29 to 31 during the run.

As soon as it went to Float (and so into PWM with no MPPT) that jumped to 35v, which was what I was getting before the test began, when it was in 12v configuration and in Float as the "panel voltage" that I took then at 34.1v (rated Voc is 37.4 but you get lower Voc with low light and high temps. In this case it was poor insolation causing the low voltage.

I see on the IV curves that 5 amps I saw goes with about 600. (9 amps goes with 1000) Seems about right with all that overcasting cloud the sun was trying to work through at the time. ( It is worse now, supposed to rain tonight, so I just got that test done in time :) )
Salvo
Explorer
Jun 01, 2015
How do you know the controller is in mppt mode and not pwm? In pwm mode the controller has at least 1V drop.

You could measure that drop. Put negative voltmeter lead on controller positive out terminal, and put positive lead on controller positive in terminal.

BFL13 wrote:
By now battery holding at 25.6v ready to start, so connected array

I measured Vmp at the controller array terminals and took battery voltage and amps from the controller's display. I did not note the times, but the whole thing took under an hour since the batts were near full going in. Controller was in Bulk and doing MPPT-- So here is how it went with Vmp, V batt, Amps, output watts

29.0, 26.3, 6.0
29.8, 27.4, 5.01, 138
30.1, 27.7, 3.52
30.4, 28.7, 4.64
30.4, 29.3, 4.81, 142
30.7, 29.9, 4.66
31.0, 30.2, 4.52
31.1, 30.3, 4.04, 137
BFL13
Explorer II
Jun 01, 2015
JiminDenver wrote:
In that layman explanation of MPPT and PWM, It says that the MPPT controller decides what voltage would best charge the battery. This seems to be an example of that.

It also shows the Eco-Worthy is indeed "worthy" Thanks again, Jim. You got it right.
JiminDenver
Explorer II
Jun 01, 2015
In that layman explanation of MPPT and PWM, It says that the MPPT controller decides what voltage would best charge the battery. This seems to be an example of that.

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60 Cell Panel vs 24v Bank MPPT and PWM UPDATE

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