Efficiency Test Results -MPPT Controller (Eco-Worthy) UPDATE

[BFL13]

Update 22 April

Got some results today on measuring for controller efficiency. The numbers jump around while you are trying to take them so total accuracy is impossible, but several tests were all in the same ballpark, so here is a typical test result using my set up of a 230w Hanwha panel and the Eco-Worthy 20a MPPT controller.

Test conditions- sky fairly steady in some haze, no clouds going by to screw things up. I ran battery loads to keep battery voltage steady in the 12s. Panel specs: Voc 37, Isc 8.3, Vmp 30, Imp 7.7

At the panel- 35C panel, 17C ambient, cooling breeze on panel tilted up, pointing at sun. 35.2 Voc, 7.7 Isc

For the test I inserted the meter set for amps between the panel neg pigtail and the neg wire to controller, got 6.4 amps (which was the Imp) at 29.5 volts at the panel.

At the controller input got 29.2 volts for Vmp, so line loss was 0.3v about 1%, which is what I was getting last year with the same set-up.

The controller efficiency is between its input and output watts.
INPUT- 29.2 x 6.4 = 187 watts
OUTPUT- 12.7v x 14.06a = 178.6 watts controller display said 178watts

Calculation: 187 - 178 = 9 and 9/187 is a 4.8% loss, so controller efficiency was 95.2%

The other tests all came out in the same ballpark with efficiency in the mid-90s.

Actual controller efficiency varies under various conditions and there are curves available for some models. I don't have the curves for the Eco-Worthy.

I have seen curves for other brands that show efficiency is reduced to the mid 90s when the controller is working nearer its max ratings for amps and watts. So the 230w and 14a is against the Eco-W's 250w and 20a ratings, which makes its measured efficiency here in the mid-90s reasonable compared with other MPPT controllers.

Later someday I will get another set of readings for when we are at STC under blue sky and higher ambient temp to compare with these.

[BFL13]

It looks like controller efficiency goes up with cooler ambient temp at the controller. ( I am on limited data right now so can't look up those efficiency curves for the Tracer MPPT or any other's to confirm)

It does not seem to make any difference that the 230w/15a is close to the controller rating 250/20 like I thought it did.

So it is all about panel temperature that kills your amps with MPPT. I still need to run a test with the 230w panel and PWM with batts at 24v. I expect to get the panel Isc of the moment at the batts same as with 12v panels and 12v batts with PWM.

That would have made my amps 8.87 above, which is like 17.7 on 12s so it would still have beaten the MPPT/12v at 16.4 even with such low panel temps as yesterday's. If that proves out, then there could be "consequences"

[JiminDenver]

Thanks BFL. It's nice to see the numbers for the Eco-w. It proves effective can be affordable, durable and simple to use.

[BFL13]

MrWizard wrote:
I think you have a very effective system

Thanks. I followed the advice on the forum here for how to do the wiring etc. JiminDenver gave us all a good steer towards this 230w panel with an Eco-Worthy controller combo.

Got more amps this afternoon with the sun higher. Same panel/ambient temps as this morning but now panel Isc is 8.87 (rated 8.3) so insolation is more.

INPUT- 28.9v x 7.3a = 211w
OUTPUT- 12.7v x 16.4a (wheee!)= 208w

Calculation: 211-208=3 and 3/211 = 1.42% so efficiency is 98.6%

[MrWizard]

I think you have a very effective system

[BFL13]

New results when at estimated STC today and with cool panel and ambient temps.

Blue sky, no haze, ambient 13.5C and panel at only 35.2C. As usual ran loads to keep battery voltage in the 12s for the test. Panel Isc was 8.5 (rated at 8.3 so IMO at STC for insolation)

INPUT- (numbers jumping around probably due to MPPT action, but these seem to be about the middle values to go together)

29v x 7a = 203w

OUTPUT- 12.5v x 15.84a = 198w

Calculation: 203-198 = 5 and 5/203 = 2.5% so efficiency 97.5%

I am guessing the cooler ambient temperature accounts for the higher controller efficiency than last test. I don't have a temp vs efficiency curve to compare with (anybody?)

There is obviously nothing wrong with the Eco-Worthy controller as such, so there goes the last refuge for the controller snobs to find comfort 🙂

That leaves the panel temperature as the big culprit in the summer when I was getting 13.5a at 51C panel instead of today's 15.8a at 35C panel. There is no cure for that unfortunately.

Also I don't know why I was getting 203w instead of 228w at est STC today. My line loss panel to controller is only 1% (2 from the 230)and line loss from controller to battery measures 0.02% at the 15a (ie no loss of the OUTPUT watts) Perhaps not really up to STC today?

[SteveAE]

Can you use an analog meter, or set your digital meter to average (or make a little integrator to if for you)?

[BFL13]

"From the frying pan into the fire" comes to mind 🙂

The controller keeps playing with Vmp so by the time you take one measurement the other that goes with it doesn't quite match so you can get a too wide spresd or a two narrow spread between the two measurements. Very frustrating but with practice, you can get it within reason.

I ignored any possible loss between battery and controller that might affect the percentage. I have two feet of #8 on pos and same on neg there, if anyone is fussy, that was at 14 amps and 13 volts.

[JiminDenver]

I'll be able to run the same vs the boat anchor as soon as I get things set up that is. I will be able to run them with matching panels side by side unless I sell the last set up here soon.