Author Topic: Mppt Brand Comparison Suggestions  (Read 166 times)

0 Members and 1 Guest are viewing this topic.

Offline Solarnewbee

  • Full Member
  • ***
  • Posts: 146
  • Karma: +1/-0
    • Cayenne Dashboard
Mppt Brand Comparison Suggestions
« on: March 30, 2019, 01:59:30 pm »
Hola Amigos!!!

So, after experiencing the 2 generic 80 amp 150c mppt controller on 5.4kw split in 2 sets(9 front roof and 9 rear roof) I have no idea if my lfp’s are Really getting their full due. Definitely not overcharging that’s for sure. Panels are strung in 3’s for 108v and voltage between the 2 controllers range from 100v to 121v given the time of day. Amps as high as 42 on one while other seems low at only 16amps. When I return I may have to check the wiring to see what the installers did. They may have wired it lopsided. I’ve lost 50lbs so far and just realized that’s a whole ten year old geez, i plan to be down another 50 so I can walk on roof tiles without going thru. Is there a load tester I could make that could test the amperage of each side? Something akin to the short circuit amps but not quite a short. Wire wound resister shunt and meter? I’m sure Ross, Pete, Oz, LH, CMF could draw a circuit that everybody could use if that’s even feasible. Might save me a 2 story climb.


On to the comparison;
1. MidNite controller classic 150
   Has all the bells and whistles like network and graphs etc
2. Outback FM60 or FM80 has some bells and whistles
   
I’ve heard good things about both but there seems to be two rather night and day camps and the info can have lots of grey areas

The classic 150 calculator has me at 2.1 classics. Question is, is 0.1 enough wiggle room using a higher voltage to stay with 2 classic 150’s.

Outback doesn’t have a calculator that I can find. Going to call Monday see what their take is.

Epever seems to be proliferating itself now but I would have to add cooling fans as it’s just heatsink relying on convection cooling. It has Rd-485 communication and can be strung together and user setting to accommodate lfp’s. You get a rs-485 to usb but no software. I guess there’s something out there available.

Any thoughts guys?
SN

Any day above ground is a day for potential mishaps

Offline Pete

  • Full Member
  • ***
  • Posts: 170
  • Karma: +12/-0
  • Golden Valley Tasmania
Re: Mppt Brand Comparison Suggestions
« Reply #1 on: March 30, 2019, 07:33:03 pm »
Other regulators worth looking at are Victron. They also make a battery monitor that connects to a shunt giving readouts on Volts, amps, power used, power in etc.
The way to measure the current on each string would be to use a string.
Just get two shunts that can handle the current, say two 250 amp or 500 amp shunts. Connect them to the output regulators and use two amp meters connected to them to give you the current on each string.
No need to go stomping about on the roof then.
Pete

Offline Solarnewbee

  • Full Member
  • ***
  • Posts: 146
  • Karma: +1/-0
    • Cayenne Dashboard
Re: Mppt Brand Comparison Suggestions
« Reply #2 on: March 31, 2019, 03:18:33 pm »
Thanks Pete

I have several shunts with meters and meters with ct’s. Can I just connect inline on the pv negative for each string before the controller or would that not show an accurate current? I was thymaybe reading current before and after the controller to compare readings. Also what are your thoughts about 2 or more generic controllers working against each other and preventing full use of of the kw available? I have noticed that even at high noon one controller show 1.97kw/38amps and the other.78kw amps I can’t recall, maybe 12. Maybe, it just means I got what I paid for or less than what I paid too much for?

I have another year or so to hem and haw at it as long as I do t have a burnout and have to ship something over to have a stranger install on FaceTime or Facebook messenger video.

Pics of the controllers. Not very good ones and the kwhr meter for inverter uptime. January 6-24

Very messy setup I know but when I get retarded uh I mean retired, I can work on that. I did go back and put 60 amp breakers, couldn’t find fuses over there, between where the lfp’s go back around. Basically every 4th battery. Someone recommended that. Ross or Pete or a vendor. Or both.

Thanks
SN

Any day above ground is a day for potential mishaps

Offline Pete

  • Full Member
  • ***
  • Posts: 170
  • Karma: +12/-0
  • Golden Valley Tasmania
Re: Mppt Brand Comparison Suggestions
« Reply #3 on: March 31, 2019, 04:20:46 pm »
Hi Solar, putting current shunts before the regulators would show how much current each string is putting out. but would not show how much each string is feeding into the batteries. As the MPPT controllers convert high voltage low current into lower voltage higher current.
It would be best to put the shunt in the negative line after the regulators that would tell how much current each regulator were feeding into the batteries.
I have three MPPT controllers on my system, I monitor the total current on the outputs but also have a fairly cheap Clamp Meter that I can check to see what  each regulator is doing.
My system is pretty simple, works great, even on cloudy days ( which we have plenty of) we still get enough power.
We don't have big power usage though. No air conditioning, wood heating, 12 volt lights, 12 volt fridge, and power everything we can without the inverter. We only turn the inverter on when we need it. So our 2kw system is more than adequate for us.
Have fun with being retired. when you get there, it is a great time of life. I really can't figure out how I had the time to go to work when I did.
Pete

Offline Solarnewbee

  • Full Member
  • ***
  • Posts: 146
  • Karma: +1/-0
    • Cayenne Dashboard
Re: Mppt Brand Comparison Suggestions
« Reply #4 on: April 06, 2019, 12:53:48 pm »
According to a calculator I found online, my 800ah’s should equal almost 22kwh’s. (24v)Looking at our worst electric bill last year we spent 517kwh’s /31 days(May) = 16.7kwh’s per day, correct? Possible I plugged in the wrong numbers in the calculator. So after a lengthy call with the very kind and helpful  young lady at “The Solar Biz” distributor, out west somewhere, I learned a few things that got the noodle going. The girl told me that unlike lead acid, lip bulk all the way until 100% then float. I face times with the daughter and has her change some settings. One controller had been set correctly the wasn’t so I had her match setting and boom!, the amps were kicking. She gave the system one full day of sun using appliances and what not normally and then bedroom window unit full blast for 9 hours straight and not a hiccup. Battery readings never dropped below 3.3v unlike before when by morning they read as low as 3.03 each. I did order 2 MidNite solar classic 150’s to send over there anyway. I still want to be able to monitor it better from here. Now to teach the daughter some electrical skills😮

Cheers!
SN

Any day above ground is a day for potential mishaps

Offline MadScientist267

  • Impossible Condition Curator
  • Senior Moderator
  • Hero Member
  • *******
  • Posts: 1480
  • Karma: +41/-4
  • Rules? What rules?
Re: Mppt Brand Comparison Suggestions
« Reply #5 on: July 24, 2019, 12:27:22 am »
Lithium doesn't quite bulk all the way up but the absorb rolloff we're all accustomed to with lead is definitely much shorter lived.

As for testing output of MPPT, because of how they do their thing, you really need the batteries there and not a dummy load. This is frustrating of course because the batteries have to settle out somewhere for this to work. The way I got around this with the truck system was to pull them down either to a specific point the previous night (which requires some faith in forecasters) or hitting them hard to get them somewhere just before the sun is where you want it to run the test, and then letting them rebound and hold them with a known load. Neither way is ideal but the only real way I found to replicate conditions for PV "health checks".

This is where of course the Isc metric comes in on the labels.  With the strings isolated, measure the shorted current in as quick succession as possible so sky conditions are as close as possible, and note what you get back. I combined mine with Schottky diodes in the truck, one benefit of doing so being that each string can be shorted for testing without taking anything offline. If you use a regular combiner, it's more involved obviously.

Hope that helps.

Steve
Wanted: Schrödinger's cat, dead and alive.