Quick Test of Eco-Worthy MPPT Controller

[BFL13]

Ordered it on 3 Oct arrived at the door 23 Oct free shipping.

Controller rated to 42V so watch that. EG I have it on one 230w panel, Voc 37v at 25C, so would be more Voc at cold temps.

Not able to do proper testing with Trimetric to measure, but rigged up a yard test to see if the thing worked at all 🙂

Used one full SOC 12v battery with a 400w inverter clamped on and two 100w lamps for an estimated 20a draw. Got battery to 12.5v connected controller and 230w panel (Voc 36.8, Vmp 30 , Isc, 8.34, Imp 7.67 )

The displayed voltage was confirmed with another voltmeter. Before starting, checked disconnected panel aimed at sun, got:

34.7Voc and 8.06 Isc. (Rated 36.8 and 8.34) so expected less than max amps.

Best amps on controller when aiming panel was 14.99a Didn't note battery voltage

Lost the window--sun behind trees. It works (assuming its amps read-out is to be believed) and might even get my hoped for 16 to 17 amps on a better day. So far so good. Be a while before I can do any real testing and comparisons with PWM.

Just wanted to report the controller seems ok as was posted by JiminDenver. Jim, thanks for the good steer to this controller for $102

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/26464298/srt/pa/pging/1/page/1.cfm

http://www.eco-worthy.com/catalog/mppt-solar-charge-controller-free-shipping-p-182.html

[BFL13]

I can see it if Ken meant that using MPPT with a 12v panel isn't worth it, but I am not clear on the question whether a single 240 and MPPT is superior in some way to two 120s in series and MPPT. (ASSuming the series wire is not a problem)

The other test did show that you needed fatter wire from two 120s in parallel than from two 120s in series. I am unclear if the test showed, given the fatter wire, you would do better with one or the other and MPPT.

[ktmrfs]

ken white wrote:

BFL13 wrote:
It is all about whether, at "normal" temps, the MPPT advantage over PWM is lost. Seems it could be, but my incomplete results are encouraging that it won't be entirely lost, leaving some sort of MPPT "gain" to justify the controller's higher cost.

I'll bet money the MPPT still outperforms the PWM as long as higher voltage panels are used...

Don't compare the MPPT to PWM with low voltage panels since it is not designed to have an advantage there...

I went from PWM to MPPT with initially parallel 12V panels. There still was an advantage, but yes, more advantage with series connected or high voltage panels.

And the post I did earlier trying to do a side by side mostly looking at the effects of long cords, but it verified MPPT still had an advantage. With short (<10ft) #8ish connection, PWM maxed at 9.5A while the MPPT was showing between 10.1 and 10.4A

Previous use showed the PWM pretty much maxed out at 9.5A. However, in good summer sun, the MPPT yields 12a series or parallel with short interconnect. But in parallel, a long cable run does loose the advantage.

so it comes down to how much the extra 2.5A (20%) is worth to you if you can use a series connection.

[BFL13]

Are you saying it is ok to compare two 120s in parallel and PWM with a single 240w and MPPT, but not with two 120s in series and MPPT?

[ken_white]

BFL13 wrote:
It is all about whether, at "normal" temps, the MPPT advantage over PWM is lost. Seems it could be, but my incomplete results are encouraging that it won't be entirely lost, leaving some sort of MPPT "gain" to justify the controller's higher cost.

I'll bet money the MPPT still outperforms the PWM as long as higher voltage panels are used...

Don't compare the MPPT to PWM with low voltage panels since it is not designed to have an advantage there...

[BFL13]

It is all about whether, at "normal" temps, the MPPT advantage over PWM is lost. Seems it could be, but my incomplete results are encouraging that it won't be entirely lost, leaving some sort of MPPT "gain" to justify the controller's higher cost.

[JiminDenver]

Like MPG ratings for cars, the rated specs on a panel is something most will never see. This is just a way for them to give us realistic expectations and not send the panels back because they don't put out rated levels.

I spent the weekend staring at either a DVM or a thermometer taped to the back of my panel. It was the high 60's and the highest I saw was 120 f or 48,89 c. Since my panels track the sun there isn't much I can do. If I change the tilt and get a lower temp, I loose amps.

My biggest decrease in output was going from the mid 80s to the 90s, from the 90s to 120 did drop output some but only a tenth of a amp.

BTW if you are checking for short circuit amps on a cheap meter, do it fast. Those leads get hot quickly.

[BFL13]

This Normal Operating Cell Temperature (NOTC) spec is something I have not noticed before in the specs, but it is there.

My Sharp 130w says 47.5C, my newer Hanwha 230w panel is 45C + or - 2C. The spec for the newer 235w replacement for their 230w is 45C + or - 3C

Somewhere in the recent threads there was a set of specs that gave the ratings for NOTC which are lower than for STC so I got the idea they are softening us up to accept lower performance 😞

The 12v Sharp still gets me STC Isc in the summer, but with MPPT being voltage dependent so much, paranoia suggests "they" want you to get used to lower MPPT amps than you expected and call that "normal."

[ktmrfs]

BFL

At least I think it was you. Asked about temp effects and what temp panels are referenced to.

well, I just got a 100 W portable panel from solar world. And looked at the panel spec's. Nominal panel temp for rated spec's for Imp and Isc and Vmp is 47C.

Which works out to pretty close to the panel temps I was seeing in my report on MPPT controllers for panel temp at a 70F ambient.

[mena661]

ktmrfs wrote:
Given that, even on a clear day High RH could have a slight effect on solar panel output.

Good stuff!

[SteveAE]

It sure seems to me that there would be more success comparing controllers and/or panels, if a known light source(such as a, soon to be extinct, a 100 watt bulb run on a given input voltage, placed a fixed distance from the panels). Sure, your output will be less, but at least you won't be trying to eliminate the, very complex, variability of solar input. Just my 1/2 cents worth....

Steve

[BFL13]

Dew next morning after a dusty day leaves mud on the panel. Need to clean off panels first thing every morning in dew seasons.

[ktmrfs]

noticed another interesting solar effect this am. panels in direct sun but only about 2A output.... hum..... wandered outside, real humid last night and foggy. Portable panels covered with dew. grabbed a squegy (sp?) and wiped off the panels and went back inside. Now at about 4A, a few minutes later when the rest of the moisture evaporated, 6A. still some light fog in the air. So, water, in clouds or on the panel do have a noticeable effect on solar panel output. Given that, even on a clear day High RH could have a slight effect on solar panel output.

[BFL13]

Not clear what to compare that mono panel 11a to. Sometimes you see mono panels with lower Isc than same watt poly, so they would get fewer amps than the poly if 12v PWM. (not sure what happens with MPPT where Voc is 22 instead of 21) Maybe wrong to compare mono 24v with poly and PWM same wattage.

Exceeding Voc even for a second will fry some controllers. Yipes.

[JiminDenver]

The real difference is when you get a SOC of 7.2 and a mppt output of 11a on a 24v panel. (3pm yesterday)

The person with the videos may have answered the question of what happens when you exceed the VOC limit. He is using 2 12v panels and I'll have to find the VOC's but it seems he is running just below 44V total and having issues with heat. I thought he had fixed it with larger wires but a week later still had a issue.

[BFL13]

Just part of an amp mostly on the low amps I was getting. I didn't write down any numbers, just a couple of spot checks back and forth between Isc and the amps on the Eco-W (which I had confirmed were same as Trimetric) and the solar was a touch higher. Be about the same as Salvo got with his 130w if I did a full test on a proper sunny day.

With amps that low between 4 and 8 say, who cares if you get 5 or 9 instead? It's the old, "Percentage of what?" again. You can double your amps. From 1 to 2. So you get one more amp. Party time! 🙂

OTOH with a higher expected amps with PWM, you get more actual amps as the gain with MPPT. Still might not change your life having a couple more amps, but now you can get the advantages wrt wiring, fewer (but bigger) panels, series vs parallel if series happens to be an advantage in your case, etc.

For me it is about having one panel for the portable contraption instead of two (which I found awkward) and not much else. (Except the entertainment of playing with the MPPT and finding out how that works compared with what I am used to.)