Midinite 150 first impressions

NorthGuy

Re: Midinite 150 first impressions

ChrisOlson wrote: »

I'm thinking these MPPT solar controllers must have an efficiency curve like an inverter. I would like to know where the "sweet spot" is where the controller runs at peak efficiency vs capacity to determine how to size arrays to controller capacity and get the best efficiency possible. But it seems the controller folks don't publish that information like they do for inverters.

Most of the losses must be directly related to the current - the more current, the more loss - this implies constant efficiency through the operating range.

Some losses should be associated with the voltage difference between PV and battery sides. The more the difference the more are switching lossses in the MOSFET.

There also should be a constant component to run processor, display (fans for that matter), which should be very small.

But also there are invisible losses, which do not affect the efficiency measurements and do not produce heat. These losses has to do with the amount of energy taken from the panels - how close the controller is to the MPPT point, how good it is in getting the entire available energy. These losses may be substantial, but are very hard to quantify or even detect.

vtmaps

Re: Midinite 150 first impressions

Cariboocoot wrote: »

By dint of info from numerous MX users it seems they work best at about 75% load rating (i.e. 45 Amps). No info from MidNite on the Classic's efficiency curve as far as I know and not enough anecdotal evidence gathered yet to get the numbers otherwise.

Outback has published their efficiency graphs for the FX controllers. It looks like peak efficiency is at about one third of their load rating. I posted the efficiency curves for a 24 volt system here: http://forum.solar-electric.com/showthread.php?15907

--vtMaps

mtdoc

Re: Midinite 150 first impressions

Comparing 2 charge controllers with different arrays and different designs, using their displayed values is meaningless IMHO .

Midnite publishes this comparison done with identical arrays built and monitored by APRS world.

Attachment not found.

Surface temperature of the controllers is also a pretty useless measure.The XW has large cooling fins and IIRC does not have a fan. Different designs - apples and oranges. What's important is the temperature of the PCBs, Fets, etc. Is the XW designed to radiate heat to the surface where it can be dissippated or is it being trapped where it heats up the components?

ChrisOlson

Re: Midinite 150 first impressions

Thanks for that vtMaps. That's the kind of info I'm looking for on the Classic. Can't find that info anywhere for the XW-MPPT60 either. But after cooking the living snot out of my Classic for the whole last month - most days it was so hot that I had a fan blowing on it in the utility room because I couldn't even touch the front of it - I decided that attention must be paid to sizing controllers to the array capacity. You can't simply put in a 5 kW controller and put 5kw / 80% = 6.25 kW on it to run it balls out. You'll melt the frickin thing.
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Chris

ChrisOlson

Re: Midinite 150 first impressions

mtdoc wrote: »

Surface temperature of the controllers is also a pretty useless measure.

Any heat trapped inside eventually has to make it to the outside. You can't trap it in there permanently. So external temperature is a good indication of how much heat the controller is producing internally. Heat means your solar power is being turned into heat instead of electricity. The more heat you got, the more of your solar power is being lost.

The XW-MPPT60 runs amazingly cool at full rated output. And I mean dramatically cooler than the Classic with both running at 50 amps. I'm going to take more measurements over time and see if I can figure out what the rough efficiency curve is on these controllers. When you got one type that's putting out 3 kW and it's nice and cool to the touch, and another one hanging right below it that toasty hot at the same 3 kW output, there has to be a reason for it. And I don't think it has anything to do with white being naturally cooler than black :roll:
--
Chris

mtdoc

Re: Midinite 150 first impressions

ChrisOlson wrote: »

Any heat trapped inside eventually has to make it to the outside. You can't trap it in there permanently.

Agreed.

So external temperature is a good indication of how much heat the controller is producing internally.

Actually no it's not.

Heat is dissipated many different ways and at different rates. Heat generated internally will eventually be dissipated, yes, but how and when will vary. Some will be lost by conductive transfer and some by convective transfer depending on design. The conductive transfer to the metal case or cooling fins may occur rapidly or slowly- so the rate of transfer to the surface - AND to which surface- will vary depending on design. So which part of the case or cooling fins you're are testing and when you are testing it is important. The most distal part of the XWs cooling fins will be much cooler than surface closest to the components.

If a fan is involved - more effective convective heat transfer will occur and the design may involve using it to cool electronic components - not the external case - which may be designed to stay quite hot to facilitate a better thermal gradient with the surrounding air.

As far as efficiency and lifespan goes, it's the temperature of the electronics that counts, not the surface of the case.

So it really depends on the design of the controller. Have a look at THIS thread on the Midnite forum where Ryan and Bob discuss the difference in design between the Classic and MX60 as far as heat transfer.

NorthGuy

Re: Midinite 150 first impressions

mtdoc wrote: »

Midnite publishes this comparison done with identical arrays built and monitored by APRS world.

Looks a little bit suspicious. On day 7, XW SCC got only 70% of the available energy. I compared XW SCC production with luxmeter readings through the variety of lighting conditions, and it constantly gets slightly over 100% of what is supposed to be available from the rating of the panels. I attributed this to the fact that my panels might be slightly better than the ratings because of + sorting. The goal of this was to test panels. I've never seen anything remotely close to 70%.

mtdoc

Re: Midinite 150 first impressions

It's true that the published comparison only reflects one set of conditions - one identical array - one 7 day period at one location, etc -but at least it's an attempt at an objective comparison. Could there be some other biases? perhaps -though I suspect if there were you would have heard about it from APRS world, Outback or Xantrex if the data was way off...

Question for XW owners - Does the XW measure and display the temperature of it's internal components? It would be interesting to know what temp they run at.

Also - if you really wanted to measure the efficiency of the controllers and heat production/transfer, etc - you'd have to have them in a controlled environment - a thermal environmental chamber to measure heat production/loss and with controlled voltage/current inputs and calibrated instruments to measure output. Too bad Home Power magazine or another entity doesn't do these kind of comparisons...

ChrisOlson

Re: Midinite 150 first impressions

mtdoc wrote: »

Also - if you really wanted to measure the efficiency of the controllers and heat production/transfer, etc - you'd have to have them in a controlled environment - a thermal environmental chamber to measure heat production/loss and with controlled voltage/current inputs and calibrated instruments to measure output. Too bad Home Power magazine or another entity doesn't do these kind of comparisons...

If Home Power did it I'd be sort of suspicious of it anyway. Home Power, since they went to that glossy paper, isn't even good for the outhouse anymore :roll:

No, the XW controller shows nothing about internal temps. It only displays battery temp as long as there's a BTS installed on one of the components in the XW Power System.

Basically, what I'm interested in is efficiency - power in vs power out - and where the "sweet spot" is to run the controllers at better than 90% of the time. I aim to put a rough curve together for that over the next couple of weeks for my own use so I can size my arrays to the appropriate controller for best harvest efficiency and least loss to heat. Looking at my logs from yesterday, the XW-MPPT60 harvested 4.67 kWh/kW installed capacity. The Classic 150 harvested 4.5 kWh/kW installed capacity. Both controllers ran in Bulk stage all day. So that leads me to think that I'm still pushing the Classic 150 a little too hard for optimum.
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Chris

mtdoc

Re: Midinite 150 first impressions

ChrisOlson wrote: »

If Home Power did it I'd be sort of suspicious of it anyway. Home Power, since they went to that glossy paper, isn't even good for the outhouse anymore :roll:

LOL! Yes, I agree. Their "product reviews" consist of nice glossy photos and a regurgitation of manufacturer marketing data. All fluff and style - no substance.

westbranch

Re: Midinite 150 first impressions

er the cooling and fans etc. Chris is your Classic mounted on an E panel or right to the wall. Reason I ask is that the MN E-panel is/gets mounted about 1/2 inch away off the wall and if you use their Classic mounting bracket, the Classic will also be away from the wall so there is some convective cooling and possibly less fan run time

ChrisOlson

Re: Midinite 150 first impressions

westbranch wrote: »

Chris is your Classic mounted on an E panel or right to the wall.

It is mounted right on the power room wall. I didn't get the Classic mounting bracket or E-panel.

Attachment not found.

But the MPPT60 is installed the same way

Attachment not found.

So what I should do is whack out a 1/4" sheet of aluminum and mount it to the utility room wall on standoffs, then mount the Classics to it for additional heat sink capacity :cool:

--
Chris

westbranch

Re: Midinite 150 first impressions

Page 16 shows a 3D view and page 6 the shop drawings for .5 inch space

http://www.midnitesolar.com/pdfs/epanelManual.pdf

ChrisOlson

Re: Midinite 150 first impressions

westbranch wrote: »

Page 16 shows a 3D view and page 6 the shop drawings for .5 inch space

Hmmm... Guess I didn't read the Classic installation instructions very good on the air spacing behind it.
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Chris

westbranch

Re: Midinite 150 first impressions

I don't remember any discussion of it either, it was just that I am in the process of putting an Epanel together/up and had to order the bracket which came 2 days ago, and I started thinking about the attachments etc.

Added Benefit: The space also keeps your stubbies from getting squashed against the wall when positioning the Epanel!

vtmaps

Re: Midinite 150 first impressions

ChrisOlson wrote: »

Thanks for that vtMaps. That's the kind of info I'm looking for on the Classic.

from: http://midniteforum.com/index.php?topic=239.15

the electrical efficiency of the Classic 150 compared to the larger controllers, such as the MX60 is not quite as good. The MX has huge inductors and more FETs.

I did do a measurement recently on the Classic with a 12V battery and a 72 Volt array (power supply). The efficiency came out 1% worse than the MX60. Something like 92% for the Classic Vs. 93% for the MX60.

As for daily harvest in kW-Hours go, we have seen the Classic out perform all other controllers except maybe the Morningstar MPPT 60 CC where we were on par. Almost no difference and some days even more.

That outperformance has to do with the tracking ability of the Classic. Even though its electrical efficiency may not be as good, the tracking efficiency more than makes up for it comparatively.

Another thread to read:
http://midniteforum.com/index.php?topic=405

--vtMaps

Cariboocoot

Re: Midinite 150 first impressions

Understand that the Classic is an 80 Amp controller, which requires heavier components that inevitably consume more energy for themselves.

Comparing it to a 60 Amp controller is not a fair evaluation. The only other controller comparable is the Outback FM80.

On the other hand seeing only a 2% efficiency difference between the Classic and the Xantrex controllers based on anecdotal (non-scientific) evidence is pretty impressive.

ChrisOlson

Re: Midinite 150 first impressions

vtmaps wrote: »

from: http://midniteforum.com/index.php?topic=239.15

Morningstar was second. OutBack third. Xantrex was far behind

Actually, I see nothing wrong with the tracking in the XW-MPPT60. Basically, all a MPPT solar controller can do is track Vmp. I have identical panels on both of my controllers and I haven't seen them out of agreement yet on Vmp. The Classic does, however, unload the array when it does a fast sweep. The XW controller don't. But I watched them today during cloud edge effect, clear conditions, and when the sun was totally under clouds, and during a couple periods of rain. Frankly, I didn't see either one winning the race on tracking.
--
Chris

ChrisOlson

Re: Midinite 150 first impressions

Cariboocoot wrote: »

Comparing it to a 60 Amp controller is not a fair evaluation. The only other controller comparable is the Outback FM80.

I would say the Classic is really an 80 amp controller on 48V. It'll do 90+ on 12 or 24. But not on 48. Maybe 84 amps peak. But it gets so hot after two hours at 80 that it's almost scary. The MPPT60 don't appear to even be breathin' hard at 60 amps, and neither does the Classic. So in reality, I think there should be a duty cycle on that max rating. Because the temps I seen my Classic running at last week can not be good for longevity of the equipment.
--
Chris

Cariboocoot

Re: Midinite 150 first impressions

ChrisOlson wrote: »

I would say the Classic is really an 80 amp controller on 48V. It'll do 90+ on 12 or 24. But not on 48. Maybe 84 amps peak. But it gets so hot after two hours at 80 that it's almost scary. The MPPT60 don't appear to even be breathin' hard at 60 amps, and neither does the Classic. So in reality, I think there should be a duty cycle on that max rating. Because the temps I seen my Classic running at last week can not be good for longevity of the equipment.
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Chris

In an off-grid application one would not expect to see "continuous" maximum current. If you do, something is wrong. Current should go down as the battery comes up in charge, and this is a process that usually begins before the array is capable of supplying maximum current.

For a hybrid grid-tie system it is different, because the battery will not be cycled most of the time and the array should be sized to supply maximum current for as long as possible as it is being sold back to the grid.

Under the circumstances, the cooler-running "no fan" Xantrex unit may be a better choice for GT applications.

ChrisOlson

Re: Midinite 150 first impressions

Cariboocoot wrote: »

In an off-grid application one would not expect to see "continuous" maximum current. If you do, something is wrong

Well. When it comes to off-grid wind power I can tell you how to do it and I don't mince no words. But when it comes to off-grid solar I'm about as newbie as they get

What I did was come up with this "theory". One controller with massive over-capacity on it, and the panels aimed in three different directions. "Virtual tracking" is what I called it. Not real tracking, but close enough and no moving parts.

Then you throw a central A/C unit at it to make sure the batteries never get charged.

You want to put the severe duty test to your solar controller? Try the above.

Edit:
My Classic 150 is lots happier now that the XW-MPPT60-150 is hanging on the wall with it. It doesn't even really care that it's white instead of black. And one of the other forum members was nice enough to clue me in on how to adjust the MPPT60 so it doesn't fight with the Classic over who's boss on when absorb should end. And instead of pushing my Classic to balls out (to borrow an old steam engine term) for hours on end, I'm now getting more harvest from my arrays with dual controllers on them due to better controller efficiency.

I had it all calculated out that I should not be "wasting" any available solar power because there shouldn't have never been more than 4.8 kW available, max, at any one time. The weak link ended up being the Classic. It DID handle it. But I don't think it was good for it. And I'm also not buying that controller efficiency is not important. Because I'm seeing the same peak power the last two days. But I'm getting more kWh because I'm not turning as much of my solar power to heat in the controllers.

Live and learn. My "theory" was good but it ended up not holding water trying to do it with only one controller.
--
Chris

NorthGuy

Re: Midinite 150 first impressions

ChrisOlson wrote: »

I'm now getting more harvest from my arrays with dual controllers on them due to better controller efficiency.

Now, when you have two controllers up and running you need to install more panels to help with your A/C

Vic

Re: Midinite 150 first impressions

... This has been an interesting read.

mtdoc had a good point about the desirable function of the internal fan/s in the Classics -- they distribute the heat of internal components, which eliminates hot-spots, and helps the casting (case) dissipate the heat.

Cariboo Marc made some good points; the Classic is an 84 Amp VV at 48 V, and comparing it to a 60 A CC is perhaps not quite fair.

Believe that one of the design goals of the Classic was to make it able to replace existing CCs, which would mean that it would need to be the same nominal size and form-factor. So it could not be much/any larger than traditional MPPT CCs on user's walls -- larger size would help it dissipate heat.

Fans are always a trade-off. In my opinion, the Turbo fan shroud reduces most of the natural convection cooling of the right side of the case, where the FETs are mounted, when the Turbo is not running. And, if one wanted to add an external cooling fan, the Turbo duct/housing would reduce the effectiveness of this added fan, because the Turbo's cooling duct covers about 75% of the heat dissipating "studs" on the right of the casting.

The Classic is a great box, with many, many functions/features missing in many/most other CCs. There is a bit of a cost, under some circumstances for the added functions. The Classic is and will continue to get better and better as time progresses. This is not really true of the XW or the FM CCs for differing reasons.

And, as Chris noted, it is a bad concept to run any CC full-out for hour after hour, especially in a HOT environment. It simply cannot be a good idea.

Have, and have used the MX, Classic and XW CCs. The MX is a terrific CC, especially remembering that it was designed 11 or so years ago. The XW SCC is a stunted POS, with less than 50% of the functionality of the Classic, but probably fairly efficient in the very few things that it does. The OB FM CCs are probably OK, too. BUT, the OB CCs and the XW SCC are not directly Field Firmware Updateable. The XW needs the Magic Implanter (about US $ 325), and the MX and FM CCs need a ride to Arlington, WA (or perhaps to a distributor for units outside of the USA) for any updates. There is no perfect single solution, but the Classic is being continuously improved by an aggressive team that is always swinging for the fences, and that cannot be said about any other CC on the market (that I know of). It is not yet perfect, but it is the best solution for the needs of the systems here.

And, the MidNIte products have tremendous Customer Support via phone, e-mail and on the MidNite Forum.

Just try to sign up for the Schneider Forum!

Have left out the Rogue CC, which has been a fine product and well supported my Marc, but this Thread has been dealing with large CCs.

Just Opinions, mostly from direct experience. Vic

mtdoc

Re: Midinite 150 first impressions

Good points Vic - especially about the Classics turbo fan.

It seems that current CC's take one of two tracks to deal with heat.

1) Use large cooling fins ala Morningstar/Xantrex to give a large surface area for conductive heat transfer. With this approach, since heat transfer is spread out over a much larger surface area the surface of the case will be cooler (and less hot to the touch).

2) The other approach is active cooling - using fans to generate convective heat loss (Midnite/Outback). Large cooling fins not needed - hence hotter case temp. Fans require some power but can direct the cooling to where it's most needed and since convective heat transfer is more efffective than conductive transfer - you get a lot of bang for your buck (or your milliamps as the "case" may be!)

I trust Robin and Bob know what they're doing and they made a design choice based on their extensive experience...

Chris - What are your Classics PCB and FET temps when your Classic is loaded down? That is the important bit as far as longevity - not the case surface temp.

I believe the turbo fan is supposed to come on at 58 degrees C - which would burn skin a a few seconds. Electronic components are designed to withstand much higher temperatures than the human body!

ChrisOlson

Re: Midinite 150 first impressions

Vic wrote: »

XW SCC are not directly Field Firmware Updateable.

Yes, they are. Schneider just changed all that. The firmware in any XW or SW Power System component can be upgraded over the local network (wireless if you wish) right from your PC with the Conext ComBox.

And I disagree that the XW-MPPT60 is a "stunted POS, with less than 50% of the functionality of the Classic". If you need a controller to do what controllers do - harvest solar power - it is a fine controller. But Schneider also just changed all that too - put a XW controller on a Xanbus network with a ComBox and it does way more - including emailing you daily energy production summaries if you want, or sending off an email or text message to your cell phone if there's a problem with your system.

As soon as the ComBox makes it thru the retail channels and hits the street, Schneider will have THE most comprehensive total system management tool ever devised for an off-grid or grid-tie power system. Even logging power produced by your generator on a daily, monthly and yearly basis and graphing it for you in your web browser.

All the manuals for it, including the Modbus maps, are available for download now and I've been studying it. I can't wait to get my hands on one and get it bolted to my power room wall. It does everything I've always wanted to be able to do for power logging without having to have a PC running 24/7 to do it.

So the "other guys" haven't been sitting around on their collective rears either.
--
Chris

ChrisOlson

Re: Midinite 150 first impressions

mtdoc wrote: »

Chris - What are your Classics PCB and FET temps when your Classic is loaded down? That is the important bit as far as longevity - not the case surface temp.

I rarely look at the Temps menu. But when I recorded my power logs from July 19 I made a note in the logs that the Classic had de-rated for most of the afternoon to 70-75 amps because it was overheated. And I had a fan blowing on it besides. So whatever temperature it de-rates at, that's what it was.
--
Chris

mtdoc

Re: Midinite 150 first impressions

ChrisOlson wrote: »

I rarely look at the Temps menu. But when I recorded my power logs from July 19 I made a note in the logs that the Classic had de-rated for most of the afternoon to 70-75 amps because it was overheated. And I had a fan blowing on it besides. So whatever temperature it de-rates at, that's what it was.
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Chris

What do you mean by "the Classic had de-rated" ???

Is the turbo fan coming on?

Perhaps you have a warranty issue.

ChrisOlson

Re: Midinite 150 first impressions

mtdoc wrote: »

What do you mean by "the Classic had de-rated" ???

Is the turbo fan coming on?

Every fan that could blow in it was on at full blast. If you get a Classic hot enough it automatically cuts its amps back to save itself from destruction. I don't know how hot that is. But it's hot. Even the front of the controller was sizzling hot that day and you could not touch the thing.

There's no warranty issue with it. It works fine. It was just plain hot and our ambient temperature here was 102F that day.
--
Chris

SkiDoo55

Re: Midinite 150 first impressions

ChrisOlson wrote: »

Yes, they are. Schneider just changed all that. The firmware in any XW or SW Power System component can be upgraded over the local network (wireless if you wish) right from your PC with the Conext ComBox.

And I disagree that the XW-MPPT60 is a "stunted POS, with less than 50% of the functionality of the Classic". If you need a controller to do what controllers do - harvest solar power - it is a fine controller. But Schneider also just changed all that too - put a XW controller on a Xanbus network with a ComBox and it does way more - including emailing you daily energy production summaries if you want, or sending off an email or text message to your cell phone if there's a problem with your system.

As soon as the ComBox makes it thru the retail channels and hits the street, Schneider will have THE most comprehensive total system management tool ever devised for an off-grid or grid-tie power system. Even logging power produced by your generator on a daily, monthly and yearly basis and graphing it for you in your web browser.

All the manuals for it, including the Modbus maps, are available for download now and I've been studying it. I can't wait to get my hands on one and get it bolted to my power room wall. It does everything I've always wanted to be able to do for power logging without having to have a PC running 24/7 to do it.

So the "other guys" haven't been sitting around on their collective rears either.
--
Chris

Still waiting for a street price on the ComBox from NAWS, there purchasing dept is working on getting them in. Just about first on the list I hope if they take them in order of requests for them? Will be way better than the RS232 logging that they have. Tried to get source code so my son could fix the problems and modify the Conext View to display and work correctly for a 2 inverter setup but that didn't get much response. Some real good features on the ComBox, can't wait.

mtdoc

Re: Midinite 150 first impressions

ChrisOlson wrote: »

Every fan that could blow in it was on at full blast. If you get a Classic hot enough it automatically cuts its amps back to save itself from destruction. I don't know how hot that is. But it's hot. Even the front of the controller was sizzling hot that day and you could not touch the thing.

There's no warranty issue with it. It works fine. It was just plain hot and our ambient temperature here was 102F that day.
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Chris

If it's getting hot enough that it is cutting back its output and it is not being loaded past it's specs or in an ambient temp beyond its specs then there is likely something wrong with the CC or its installation. I would call Midnite.

Couid be wrong but I don't believe there is a normal programmed "derating" that kicks in at a specific temp that is part of normal operating conditions. If it is getting so hot that it has a dramatic power output cut, something is wrong.