Midinite 150 first impressions
Comments
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Re: Midinite 150 first impressionsIf 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 it's 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.
Nope - they de-rate based on some internal temp sensor. I've overheated 'em with wind turbines before too. When it de-rates it unloads the power source and lets the voltage climb on it to reduce amp output. The last time before this when I had a Classic de-rate due to getting too hot, I cooked a voltage clipper to a crisp and all that was left of it was some burnt black stuff in the box. The clipper caught on fire and burned for about 15 minutes before I discovered it. That's why I put my clippers outside on a separate service panel that is not connected to the utility room. I don't trust 'em inside a building.
I made an emergency clipper out of a garage door spring that day to stop the turbine and the voltage went well over 200 volts a couple times before I got it stopped. But the Classic was still fine. I designed a new oil-cooled clipper now and it will take a lot more kW to burn the oil-cooled one up.
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Chris -
Re: Midinite 150 first impressionsChrisOlson wrote: »Nope - they de-rate based on some internal temp sensor. I've overheated 'em with wind turbines before too. When it de-rates it unloads the power source and lets the voltage climb on it to reduce amp output. The last time before this when I had a Classic de-rate due to getting too hot, I cooked a voltage clipper to a crisp and all that was left of it was some burnt black stuff in the box.
Right. I'm not saying they don't have a prgrammed way to cut power to protect themselves if overloaded or too hot, I'm saying they should not get that hot under normal circumstances - i.e. if power input and environmental conditions are within spec. If it's doing that then something else is going on.
Add: A look at the Classics manual shows that it lists a "derate current" of 80 amps at 40 degrees C (104F) -
Re: Midinite 150 first impressionsRight. I'm not saying they don't have a prgrammed way to cut power to protect themselves if overloaded or too hot, I'm saying they should not get that hot under normal circumstances
Yeah, well there's two things that can overheat one - my "virtual tracking" deal that I dreamed up. And wind turbines. When the wind blows it don't care about no hot Classic. Wind power is relentless and it goes for hours on end without a break.
When the turbine burned up the clipper the Classic completely unloaded the turbine and went into HyperVOC. It never did come out of HyperVOC. The clipper caught on fire and welded the contacts in the contactor for it and then the controller shut completely down when it went over 200 volts and even stopped controlling the clipper contactor (which was already welded anyway). I was already there trying to figure out how to stop the confounded thing by that time because I heard it from inside the shop. Have to use a "soft stop" with some resistance to prevent damaging the stator in the turbine when it's pushing 6 kW at the shaft.
If the Classic gets too hot and it can't control it with the current limit, it will just go to RESTING and that's what happened with the turbine.
Just hook enough power to it to try it and you'll see what I mean.
Edit:
On July 19 I was there watching that one. The Classic unloaded the solar and let the voltage go up to about 100 volts and the output amps dropped to 70-75. Normal volts in that temperature would've been around 80. It never changed all afternoon until the sun started going down and then it loaded the panels back down to about 80 volts. But they weren't putting out full power anymore so the amps gradually dropped until dark, and so the input voltage.
Next day the controller is fine again and right back to putting out 83-84 amps.
But that's when I started worrying about it and decided I had the wrong setup. Can't push your controller that hard, despite what it's rated at. It's not good for it to get that hot. I had to do a bunch of wiring in the utility room to split the solar arrays out and put in a second controller. So it took a few days to get it done.
But I think the moral to the story is that just because the Classic says 96 amps on it (or whatever, based on system voltage), that is not a continuous rating for the controller. It gets way too hot to my way of thinking. Maybe boB and Robin designed it to take those kinds of temps. But I sort of prefer to have the controllers run a little bit cooler because heat kills any electronic thing I've ever seen.
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Chris -
Re: Midinite 150 first impressions
Derating anecdote:
NEC classifies continuous use as "three hours or more" and requires a 20% derating for a device operated that way. In the case of a solar charge controller this tends not to be necessary for the reason I mentioned before; whereas technically it is in use for three hours or more it will not be at full current. Some (few) controllers state specifically that no derating is required at all.
Now in the case of feeding it constant power from a turbine it will be potentially at full power for 3+ hours. In that case it may be wise to follow the 20% rule. As such a Classic then becomes a 64 Amp controller on 48 Volts.
Chris is completely right about heat being the enemy; much of the current handling ability of any conductor is a matter of heat dissipation. It is also completely right that the point where that matters is the component level, not the case. Having the case get too hot is an issue for being around it, but does not necessarily indicate improper function.
Of course if anyone thinks their Classic is an inferior controller there are plenty of people willing to haul them away, and they won't even charge you much for the service.
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Re: Midinite 150 first impressionsChrisOlson wrote: »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.
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Chris
I have noticed that the current XW install and operation documentation does not include the XW80-600 CC. There is a separate install doc for the XW80-600 CC. Probably similar to the XW60-150, but need to read and compare a bit more.
Cheers
Ernest -
Re: Midinite 150 first impressionsChrisOlson 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.
OH!! I thought that the ComBox was the Schneider GateWay II. My mistake.Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes. 25 KVA Polyphase Kubota diesel, Honda Eu6500isa, Eu3000is-es, Eu2000, Eu1000 gensets. Thanks Wind-Sun for this great Forum. -
Re: Midinite 150 first impressionsCariboocoot wrote: »Now in the case of feeding it constant power from a turbine it will be potentially at full power for 3+ hours. In that case it may be wise to follow the 20% rule. As such a Classic then becomes a 64 Amp controller on 48 Volts.
Well, this is kind of my ramblings on it:
On wind the Classic is the only game in town. And wind turbines themselves are notoriously inefficient devices, usually getting less than 25% of the kinetic energy flowing thru their rotors to the battery, even with a turbine that's better than 40% efficient at the rotor. And usually only doing it at very high cost/kWh.
So a controller that runs at 90% electrical efficiency doing the conversion from high voltage transmission power to low voltage battery power is a moot point when you consider that without it, the losses in low voltage transmission at the distances that most wind turbines have to work with is prohibitive. In most cases, without the Classic controller on a battery charging wind turbine, you are down to less than 12% total efficiency. The Classic basically doubles (or even more) the amount of usable power harvested by a battery charging wind turbine. The money spent on a Classic controller for a wind driven battery charger is worth every dime, considering what it costs otherwise to even install the thing properly.
On solar where wire runs can be kept to reasonable lengths, I think controller electrical efficiency is an issue. If my math is right (and I don't think it's far off) a difference of 2% efficiency on a 6 kW array in our area can add up to 3 full days of our normal daily energy consumption over a year's time. So if somebody tries to tell me that tracking is where it's at and controller electrical efficiency is a moot point, I'm going to frown and go "what?"
I don't have anything to go on, really, from when we installed the extra solar capacity this spring because I never considered it a "problem". But based on some of my measurements I've done over the past few days my (unscientific) conclusion is that the Classic runs somewhere in the high 80's to 90% on electrical efficiency at BOP (Balls Out Power). And somewhere in the low 90's at 75% BOP. If I run the math on my numbers it becomes apparent that it is well worth the money to install a second controller to reduce the load on them below 75% BOP - both from an equipment longevity standpoint, and energy harvest standpoint.
If it runs at 75-100% BOP less than about 5-10% of the total time online (I think 10% would be stretching it), then you're probably not justified in spending the extra money on a second controller.
That's my (very unscientific) conclusion. And like I said - remember that when it comes to solar power I pretty much bumble along and hope it works. But I learned something about controllers from my "virtual tracking" project that maybe somebody else will find useful one day when they starting adding more panels to their Classic controller - OR, possibly put full rated capacity on a tracker with one.
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Chris -
Re: Midinite 150 first impressions
Chris, thanks for heat testing the Classic, I was worried about mine that live outside, and noticed that they get quite hot, never been too hot to touch, but uncomfortable. I went and checked on a 95 degree day but the controllers must have already been well into absorb as they were only pushing 15 amps into the battery (above the 28-30 amp load of the A/C) and holding 29.2 Volts. They weren't as hot as I had seen them in the past while in bulk, just running 2000 watt array on each.
...Oh, and who is Bob at MidNite? I didn't know they had a Bob... I wonder if the origins of boB have ever been discussed, I'll have to look that one up on a less busy day.Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites, Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
- Assorted other systems, pieces and to many panels in the closet to not do more projects. -
Re: Midinite 150 first impressions...Oh, and who is Bob at MidNite? I didn't know they had a Bob... I wonder if the origins of boB have ever been discussed, I'll have to look that one up on a less busy day.
Well, BoB is Bob spelled backwards. But I don't know if that has anything to do with it.
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Chris -
Re: Midinite 150 first impressions
I agree, Chris. Wind is notoriously inefficient at the best of times, and one of the worst aspects of the "small wind" is the idiotic LVDC output. Being able to run high Voltage from the turbine to the controller is a huge improvement!
Your stationary tracking (oxymoronic term for multiple fixed arrays facing in different directions invented on this forum) is certainly more economically feasible these days than a standard tracker. With panel prices what they are it's a no-brainer. Still this should not cause the controller to run at max current for long. I have a plan to do this with my system and it involves different size arrays; the largest taking the morning sun for initial bulk charging and then two smaller arrays to maintain power throughout the day. (Already knowing the usage pattern is a big help here; I'd hate to have to plan that from scratch!)
Nor am I surprised at your finding of >90% efficiency on the Classic at 75% of the current maximum; that's about identical to what MX users found over time. It seems to be a viable "sweet spot" for them.
In another thread there is a discussion of a very high power MPPT controller design. This points out one of the other Classic features: if you really do need lots of current, you can tie them together properly with the "Follow Me" function and get the equivalent of a great big controller without the problems of finding components that can handle massive amounts of current.
Over-all the Classic has a very large number of features which makes it a highly adaptable controller; beyond the abilities of any other in fact. But this is not always what is needed either. That is something that always confuses newcomers: the notion that there isn't only one way to do it, and that you have to decide which way to go depending on your particular installation. Sometimes even when you pick what seems best at the time once it is all in place it turns out not to meet your needs as well as you thought. Have any of us not adjusted something after installation?
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Re: Midinite 150 first impressionsCariboocoot wrote: »NEC classifies continuous use as "three hours or more" and requires a 20% derating for a device operated that way. In the case of a solar charge controller this tends not to be necessary for the reason I mentioned before; whereas technically it is in use for three hours or more it will not be at full current. Some (few) controllers state specifically that no derating is required at all.
My XW SCCs were supposed to work at 88% of rated power, however in the spring time panels are overproducing, and they work at 100%. It probably doesn't last 3 hours, but I don't see them getting hot at all.
Chris first brought the extra heat as a measure of efficiency. All the energy lost inside controller get converted to the heat. Somehow the discussion moved away from this, to the heat as a harm to electronics, which is a totally different topic.
There are several links in this thread to MN forums where creators of the Classics say that it is indeed less efficient than others because smaller components (they specifically mantion mosfets and inductors). That's why it needs a fan, while XW can get away with a simple heat sink. Heat sink without a fan is far superior, because it is way more reliable, doesn't use energy, and doesn't make noise. But fan is far superior in removing heat. Therefore, if you produce a lot of heat, as Classic does, you have to have a fan. If you don't produce so much heat, as XW, you can get away with a simple heat sink. Although fan is definitely cheaper than the massive heat sink used in XW.
Back to the efficiency, the Classic's creators claim that Classic tracks MPPT much better than others, and therefore produce more energy despite of lower efficiency. If it can get 1000W from the panels where XW can only get 900W, then 2% loss in efficiency might be not that important. Because 94% of 1000W is 940W, which is more than 96% of 900W (864W). Unfortunately, it is much harder to measure and quantify than the measurement of efficiency that Chris did. -
Re: Midinite 150 first impressionsBack to the efficiency, the Classic's creators claim that Classic tracks MPPT much better than others, and therefore produce more energy despite of lower efficiency.
I'm not buying that one. All the controller can adjust is Vmp. I have yet to see where the two controllers don't agree within a volt on identical panels for more than a second or two when both are running in Bulk. The XW is definitely more efficient electrically.
I have also determined that what it says on the display or SCP for the MPPT60 can be taken at face value. I've never seen yet where it disagrees with my Sun tester. The output numbers on the Classic are good and also agree. But the input numbers are suspect on the Classic - sometimes. I've seen several times where it claims it is outputting more power than what is coming in. And I've also seen some times that it agrees with the tester on input. I rechecked the voltage calibration on the PV IN and it agrees with my volt meter. So it's the amps that's off.
So I think the Classic only has one shunt in it on the output and it must be calculating input amps in software. But even those calcs are off because I've caught the controller claiming it was running at 100%+ efficiency several times. The MPPT60 has two - both on the negative leads - one on PV(-) and the other on Bat(-). Before I installed it I had to see what's in it so I pulled the front off it. The shunts are right below the buttons on the front side where the wires hook up.
So basically, you can snap a photo of the PV IN and DC OUT on the MPPT60 Meters Screen on the SCP for the XW and calculate efficiency pretty accurately. To calculate it on the Classic you must have the external tester on the input because you can't trust what it says on the display.
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Chris -
Re: Midinite 150 first impressions
No doubt that heat is detrimental to electronics. Hotter = more resistance - no getting away from that.
Interestingly a look at the XW and Morningstar controller specs - they list operating environmental temp up to 45 C vs 40 C for the Classic and Outbacks - so clearly big cooling fin heatsinking works well in high ambient temps. You do end up with a bigger controller - as always design tradeoffs..
I'm just glad I live where high temps are not a concern. It rarely gets over 80 F here.:p I like that I can see the FET and PCB temps on my Classic - which is really were the money is as far as important temps. Mine never seem to get much over 55 C even when my utility room is a swealtering 72 F . 55 C is nothing for electronic components and the Classic turbo fan does not even come on until 58 C - that's why I'm curious what Classic owners who live in hot climates are seeing for PCB and FET temps.
FWIW - here's the data from yesterday (ambient utility room temp about 72 F):
Attachment not found.ChrisOlson wrote: »I'm not buying that one. All the controller can adjust is Vmp. I have yet to see where the two controllers don't agree within a volt on identical panels for more than a second or two when both are running in Bulk. The XW is definitely more efficient electrically.
I have also determined that what it says on the display or SCP for the MPPT60 can be taken at face value. I've never seen yet where it disagrees with my Sun tester. The output numbers on the Classic are good and also agree. But the input numbers are suspect on the Classic - sometimes. I've seen several times where it claims it is outputting more power than what is coming in. And I've also seen some times that it agrees with the tester on input. I rechecked the voltage calibration on the PV IN and it agrees with my volt meter. So it's the amps that's off.
So I think the Classic only has one shunt in it on the output and it must be calculating input amps in software. But even those calcs are off because I've caught the controller claiming it was running at 100%+ efficiency several times. The MPPT60 has two - both on the negative leads - one on PV(-) and the other on Bat(-). Before I installed it I had to see what's in it so I pulled the front off it. The shunts are right below the buttons on the front side where the wires hook up.
So basically, you can snap a photo of the PV IN and DC OUT on the MPPT60 Meters Screen on the SCP for the XW and calculate efficiency pretty accurately. To calculate it on the Classic you must have the external tester on the input because you can't trust what it says on the display.
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Chris
Well - any measurement is only as good as the instrument used to measure of course. Any current or voltage measurement depends on the resolution (counts) of the AD conversion, calibration, thermal stability, etc. The best handheld clamp meters are generally only accurate to +/- 2% + some number of counts. Using my Fluke 336 (+/- 2% +3counts) the input current of both my classics is pretty darn close (+/- 1%) of what's displayed. I'm not sure what method the Classic uses to measure input and output currents but as far as I know there is no way to determine DC current by software only. You either need to measure voltage drop across a known resistor (shunt) or use a Hall effect sensor.
I think bOB had mentioned at one point that the early firmware versions did not do as good a job at zeroing out current as it should and that would be improved on.
So my 2 Classics input current is very close to the displayed value (by my measurements) but the bottom line is using a n of 1 or 2 to generalize about any instruments accuracy is fallacious by my science background way of thinking. -
Re: Midinite 150 first impressionsSo my 2 Classics input current is very close to the displayed value (by my measurements) but the bottom line is using a n of 1 or 2 to generalize about any instruments accuracy is fallacious by my science background way of thinking.
It would be interesting to see if someone else has the same problem that I have seen where the input and output do not agree. I have seen many times where the output power is (claimed) higher than input, which is impossible. You can access it by pushing the Status button twice, then snap a photo of the screen with your camera to capture the values. Then multiply amps x volts on both sides to see what you get. Many times I've found the controller running well over 100% efficiency (claimed) - on all my Classics. So something is bogus there.
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Chris -
Re: Midinite 150 first impressions
Chris; see if you can get a picture of that sometime. It would be interesting. I've never seen my MX do this, and the two controllers share certain functional aspects. Makes me wonder what they changed? -
Re: Midinite 150 first impressions
I have seen it (>100% conversion) on both the Cl 150 and the MX , BUT only at very low input amps.
I have put it down to accuracy of the device being only displaying in tenths of an amp.
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West Chilcotin, BC, Canada -
Re: Midinite 150 first impressionsCariboocoot wrote: »Chris; see if you can get a picture of that sometime. It would be interesting. I've never seen my MX do this, and the two controllers share certain functional aspects. Makes me wonder what they changed?
I think boB told me once that they concentrated on getting output right (and he was concerned about getting accuracy closer than 2% on that side) and the input is basically a calculated value. They measure input voltage (and you can calibrate that in the TWEAKS menu). But the amps is calculated. I'm also running beta firmware in all my Classics - I haven't run production firmware in any of them since they were new because I'm always testing stuff and providing feedback to boB on what I find.
I went out the utility room and looked. It's drizzling here now and the solar output has dropped down to below 100 watts. And, of course, right now it agrees dead on with the Sun tester. But I'll see if I can catch it when it shows some bogus values.
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Chris -
Re: Midinite 150 first impressions
Yeah - that's an interesting observation, phenomenon you're seeing there Chris. I've never seen that but then again I don't spend a lot of time looking at the MNGP display. When I have looked at that screen, I've never seen what you describe but the voltage and amp numbers do update quite quickly and faster than my brain can do the math.
I think bOB has said the displayed input current accuracy is not always great - not due to the measuring hardware but due to software calibration of the hardware data, etc and will eventually get better. I've only checked it against my clamp meter a couple of times - so no large data set there.
I have no concerns about the reported power output of my Classics because they're confirmed by my Outback inverter numbers. Since I am using or selling all my PV production the inverter output corresponds well with my PV output. I generally see between 80-83% of my Classic reported PV output as inverter output. This is right in line with 90-93% imverter efficiency X battery input/output efficiency. Based on postings to the Outback forum, I know others using the same inverter have seen about the same ballpark numbers with Outback controllers. If my Classicc were overreporting output then my conversion efficiency would be unrealistically high!
I'm currently working on a high resolution system to measure voltages and AC and DC currents in/out of my ePanel. Once I get that in place I'll have a lot of accurate data to look at. -
Re: Midinite 150 first impressionsChrisOlson wrote: »...
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 ...
Well, Great Minds think alike!!
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See posts beginning 7/19/12 - 9:26 PM, and on 7/20/12 - 10:23 AM by Gordon-Loomberah :
http://forums.energymatters.com.au/solar-wind-gear/topic1507-40.html
A member here, gww, posted a link to this on this Forum, either directly to energymatters, or to the Outbackpower Forum, where Gordon mentioned his "Virtual Tracker" approach Virtually identical to what you are describing ...
Nice to see that this works well, as some of the common wisdom had been that each different PV orientation SHOULD have its own CC, and so on, FWIW, Keep cool, VicOff Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes. 25 KVA Polyphase Kubota diesel, Honda Eu6500isa, Eu3000is-es, Eu2000, Eu1000 gensets. Thanks Wind-Sun for this great Forum. -
Re: Midinite 150 first impressionsNice to see that this works well, as some of the common wisdom had been that each different PV orientation SHOULD have its own CC, and so on, FWIW, Keep cool, Vic
One of the reasons this has changed is because of the improvement in MPPT controllers (makes no difference for PWM controllers). When the old MX60's did a sweep it interrupted power for a while and played around finding the right V*A from the array. With multiple arrays facing in different directions it could come up with numbers that weren't right for any of them. The new controllers don't have this lagging sweep, so essentially V stays the same on any array attached and the maximum current will be found from whichever has the most insolation. At that point less illuminated panels contribute whatever they can while held at the "ideal" V.
Well that was a rambling and confused oversimplification.
Let's just say the continuous-adjusting controllers work better and don't get confused so easily. -
Re: Midinite 150 first impressionsI have no concerns about the reported power output of my Classics because they're confirmed by my Outback inverter numbers.
I've found the output numbers of the Classic to be spot on, agreeing with my Sun tester anyway. But I know they got a shunt in the Classic to measure output current. There's supposed to be a new shunt outfit coming pretty soon that tells the Classic exactly how many amps is actually going to the battery so the End Amps works right. I've been waiting for that but haven't seen it yet.Nice to see that this works well, as some of the common wisdom had been that each different PV orientation SHOULD have its own CC, and so on, FWIW, Keep cool, Vic
Vic,
I never seen no evidence that supports having to have a different controller on the different arrays because of Vmp. It works perfectly fine (at least here) that way. When I first put it in I threw the disconnects on the east, south and west facing portions of it to see if the Vmp was off after the controller re-tracked it. It never was.
The main problem I had was going overboard with it and putting too many panels on one controller.
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Chris -
Re: Midinite 150 first impressionsCariboocoot wrote: »The new controllers don't have this lagging sweep, so essentially V stays the same on any array attached and the maximum current will be found from whichever has the most insolation. At that point less illuminated panels contribute whatever they can while held at the "ideal" V.
'coot - that's kind of a weird way of putting it
Our east/west arrays are on 5/12 roof slope so they're tilted at 22.6 degrees. Yesterday I saw over nameplate from both of those arrays combined at solar noon. With a huge boost in early morning to noon (because 66% of the east/west is on the east slope). The east facing is producing approximately 3x more power at 7:00AM and 5x more at 8:00AM than the south facing that's over twice the nameplate size and is tilted at 30 degrees for summer. That's how good it works.
The sun comes up in NE so it doesn't even start shining on the south facing array until about 7:45AM this time of year. And by that time the east facing has been producing decent power for almost two hours.
But it sure is hard on the poor controller starting at about 10:00AM when the whole works goes to BOP
Edit:
Actually, that's not right - our roof slope is 4/12 not 5/12. So I think that's about 19 degree slope. The west facing array starts getting sun at about 9:00 and it "kicks in". By 10:00 the whole system is in Nuclear Meltdown for the next 5 hours.
Even if those panels don't work at all in the winter, I've already gotten what I consider my "money out of them" this summer so far.
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Chris -
Re: Midinite 150 first impressions
The Classic (and Lite) have both input and output current shunt measurement. The input is not zeroed (offset) quite right at the
moment (software). It used to be but I had to remove the offset adjust because it wasn't always right. That should be addressed
at some time I think. As far as measuring hardware efficiency.... Forget it (usually) Efficiency is very hard to measure even with the
expensive, accurate test equipment like Yokagawa's (which we do have). Efficiency also changes with temperature (it gets worse).
Most companies will specify efficiency while the unit is cold. Best case.
As far as solar tracking and lower hardware efficiency being better, that's exactly what we found in side by side comparisons with
identical (very close) arrays and then swapping them, etc. This was measured using a third party system (JJ's, APRS World logging system)
We found that the Classic outdid the FM80 and XW-MPPT as far as kW-Hour. It was only a small hair better than the Tristar MPPT 60
which I expected.
The XW-MPPT controller doesn't have a fan because it spreads out its heat with that massive heat sink same at the Tristar. I've looked
at its circuitry and they use a single cylinder buck and non-synchronous rectification which usually means low hardware efficiency.
It DOES have a large inductor and lots of input capacitors (necessary with single cylinder designs) though which is good.
When I checked out the XW-MPPT (years ago, now), I noticed that when I would shade a module and watch its input voltage
go down to find the new MPP V and then remove the shading, it took almost one minute before it started to bring its input
voltage back up again. That's the big reason I believe why it seriously dragged behind the Classic in that comparison.
The FM80 was similar but they may have made it somewhat better. Hey, we all have our moments when things go
wrong. Nobody's perfect.
As far as hot Chris's Classic goes, yes, running them up close to their limit is gonna be hot and with the real high input voltage it will be
worse than with a lower input voltage for the same output voltage and current. However, maybe Chris's Classic has developed
a problem ? I would only think that though if it used to run cooler under the same operating conditions. Ambient temperature
included, input voltage, output voltage and current, etc.
As far as fans go, I don't like them either BUT at least we (MN) checked these fans out to the extreme level before we decided
to use them. We do not know of one fan that has failed yet. The blades did hit the casting on the earlier ones from time to
time until we sorted out the fit. Yeah, they're noisy too. So are the fans in my other electrical equipment and power supplies.
I don't mind fan noise myself BUT when the plastic rattles, it does drive me a bit nuts. That's when the bubble gum comes
to the rescue ! (not really)
Even though our fans keep on turning, the newer Classics that will be coming out have a new trick casting
where you can actually remove and replace the internal fans without removing the circuit boards.
boB -
Re: Midinite 150 first impressionsAs far as hot Chris's Classic goes, yes, running them up close to their limit is gonna be hot and with the real high input voltage it will be
worse than with a lower input voltage for the same output voltage and current. However, maybe Chris's Classic has developed
a problem ? I would only think that though if it used to run cooler under the same operating conditions. Ambient temperature
included, input voltage, output voltage and current, etc.
Ummm.....no. I put in that "virtual tracking" setup this spring because I figured it would run our AC unit. My theory was that if I put in the right amount of panels facing in different directions that I could bring the Classic up to full rated power in mid-morning and hold it there all day. And it worked beautiful. But I found out you can't run the Classic at 80-84 amps continuous for 5 hours when it's over 90 degrees in the utility room. Not even with a fan blowing on it. It gets hot, man, and I do mean HOT.
Now that I've removed some load from it so it don't go much over 60 amps its way happier. The electrical efficiency has to be down in the high 80's pushing it that hard for that long. And all that was doing was turning my solar power into a lot of heat. Now that I reduced the load from it I'll bet the efficiency is back up in the low to mid-90's where they should run. I've been trying to figure out where that "sweet spot" is, and my gut feeling is right around 75% of it's maximum output rating.When I checked out the XW-MPPT (years ago, now), I noticed that when I would shade a module and watch its input voltage
go down to find the new MPP V and then remove the shading, it took almost one minute before it started to bring its input
voltage back up again. That's the big reason I believe why it seriously dragged behind the Classic in that comparison.
Schneider has changed that. The MPPT60 you played with had the old P&O tracking in it. The new ones with the Build 0006 firmware have their new fast tracking in it. I checked into that and it's the same technology they're using in their megawatt-class solar power plant inverters. In fact, I watched a video on it - I think it was on their YouTube channel. But I just went to look for it and couldn't find it right now.
--
Chris -
Re: Midinite 150 first impressionsChrisOlson wrote: »Ummm.....no. I put in that "virtual tracking" setup this spring because I figured it would run our AC unit. My theory was that if I put in the right amount of panels facing in different directions that I could bring the Classic up to full rated power in mid-morning and hold it there all day. And it worked beautiful. But I found out you can't run the Classic at 80-84 amps continuous for 5 hours when it's over 90 degrees in the utility room. Not even with a fan blowing on it. It gets hot, man, and I do mean HOT.
Now that I've removed some load from it so it don't go much over 60 amps its way happier. The electrical efficiency has to be down in the high 80's pushing it that hard for that long. And all that was doing was turning my solar power into a lot of heat. Now that I reduced the load from it I'll bet the efficiency is back up in the low to mid-90's where they should run. I've been trying to figure out where that "sweet spot" is, and my gut feeling is right around 75% of it's maximum output rating.
Schneider has changed that. The MPPT60 you played with had the old P&O tracking in it. The new ones with the Build 0006 firmware have their new fast tracking in it. I checked into that and it's the same technology they're using in their megawatt-class solar power plant inverters. In fact, I watched a video on it - I think it was on their YouTube channel. But I just went to look for it and couldn't find it right now.
--
Chris
I would really like to see that video !
PS... I think you mean what they call shade- tolerant Fast Sweep. I've seen their papers on that.
Nothing new I'm pretty sure. I am guessing that they probably won't say exactly how they do it though.
Solar and P&O Classic modes are also shade tolerant. Solar is the fast one.
The tracking they ~used to use~ was dynamic... I'm pretty sure it was what they call, incremental conductance. A pretty useless algorithm
if you have any shading unless it goes far off the MPP voltage. The FM60 and FM80 was the same thing, at least for a while. It wasn't much better.
Not inherently shade tolerant which is important.
The MX60 used P&O and went just enough over the MPP hump to be able to deal with partial shading pretty well.
You'll notice that the Classic has a "depth" adjustment in its Legacy P&O setting. That's how far it goes over the MPPT hump and can be
set to lower (or higher) amounts so you don't waste so much energy being off the MPP V. Seems that about 10% (default) is just about right.
I think the "solar" mode in the Classic is the same thing you just described, but if it's what I think it is, that is more for battery charging
and not so much for grid tie because it goes off for a moment and would cause light flickering.
Maybe they interleave inverter sections so that it isn't as noticeable. Maybe it's different yet.
So you were operating in a high ambient environment ? That'll certainly make it run hotter. But the Classic should adjust its current limit
downward when it gets too hot. If it does that, you should notice the bottom RED LED light up on the MNGP if it does go into
current limit. I don't suppose you saw that happen ?
boB -
Re: Midinite 150 first impressionsWhen I checked out the XW-MPPT (years ago, now), I noticed that when I would shade a module and watch its input voltage
go down to find the new MPP V and then remove the shading, it took almost one minute before it started to bring its input
voltage back up again. That's the big reason I believe why it seriously dragged behind the Classic in that comparison.
The FM80 was similar but they may have made it somewhat better. Hey, we all have our moments when things go
wrong. Nobody's perfect.
This is what I was referring to; these are the ones that can get (not absolutely will get) confused by multiple arrays.As far as hot Chris's Classic goes, yes, running them up close to their limit is gonna be hot and with the real high input voltage it will be
worse than with a lower input voltage for the same output voltage and current. However, maybe Chris's Classic has developed
a problem ? I would only think that though if it used to run cooler under the same operating conditions. Ambient temperature
included, input voltage, output voltage and current, etc.
That's something that was glossed over in the thread before: ambient temp on Chris's is really high; most people don't have their equipment operating in a room nearing 100F.
The Voltage issue is another matter. It is usually explained around here that moving the array Voltage too far from the system Voltage results in decreased controller efficiency. Not sure what array Voltage Chris is using, but obviously any controller is going to do worse with a 150 Vmp to a 48 Volt system than with a 72 Vmp.
Thanks for putting in the word of an expert, boB. And I do mean expert! You guys are responsible for the design of most of the equipment in use these days, and certainly of the best equipment. -
Re: Midinite 150 first impressionsCariboocoot wrote: »Not sure what array Voltage Chris is using, but obviously any controller is going to do worse with a 150 Vmp to a 48 Volt system than with a 72 Vmp.
I'm running theoretical 92.4 Vmp and it has to change that down to anything from 48 to 62, depending on system volts. It's not ideal but it does keep the amps down on the wire runs from the combiners. The cheapest panels to buy here (from Helios Solar Works) is the 30.8 Vmp ones. They are made for grid tie and not a true 24V panel because they won't charge a 24V battery when they get hot. But for 48V you can run them three in series and that's what I'm doing. Two in series doesn't have quite enough voltage to work unless it's really cold ambient temp.
I would like to hear from someone else who has tried to push a Classic to full power like I did for 5 hours a day to see how it fared. Like I said, the thing did do it except for one day on July 19 when it got so hot the amps from it dropped to the low 70's with not a single cloud in the sky and the sun just beating on the panels. It was so hot that day that I could not touch even the front of it. It did not seem to hurt it (the thing is obviously tougher than whale snot) but that's when I came to the conclusion that using two controllers will probably yield more energy to the battery because two will have less total loss in heat than one that's being pushed to its raw limits.
That's why I asked, and got curious about, efficiency. Despite what you say, boB, about not being able to measure it without sophisticated equipment - from where I stand on it it's a real simple thing. Power in minus power out equals losses in the controller. Power in and power out is real easy to measure with quite basic equipment. If I determine that I'm getting 5500 watts of PV into a single controller and getting 4,800 watts out, then I'm losing 700 watts someplace and my efficiency is 87%
OTOH, if I put 2 controllers on the same PV arrays and get the same 5500 watts in but now I get 5000 watts out - I am now losing 500 watts and my overall efficiency is 91%.
This is all I want to know - where is the dividing line where a person should consider going to more controllers? Ignore the nameplate rating of the controller. I want to know where you cross the line on efficiency because even though a single controller might handle it based on nameplate rating, its overall efficiency is so low at full nameplate that it's not practical. This is not a mysterious thing - it cannot be any different than motors, generators, inverters, what have you. It's just simple efficiency and duty cycle.
--
Chris -
Re: Midinite 150 first impressionsChrisOlson wrote: »I want to know where you cross the line on efficiency because even though a single controller might handle it based on nameplate rating, its overall efficiency is so low at full nameplate that it's not practical. This is not a mysterious thing - it cannot be any different than motors, generators, inverters, what have you. It's just simple efficiency and duty cycle.
I am quoting my own post because I always have to revert back to my knowledge of generators to compare electrical generating equipment.
Industrial generators have two ratings - a standby rating and a prime rating. The prime rating is always lower than the standby rating. The reason is duty cycle and Power Factor. Even though the generator can deliver standby power, it cannot do it continuously. So the generator is de-rated to its prime rating for continuous power. The prime and standby ratings are determined by efficiency of the winding and how much heat is generated in the winding vs output, and how long it can deliver standby power (duty cycle) before the output must be reduced to the prime rating.
What is the standby and prime ratings of the Classic 150 controller?
--
Chris -
Re: Midinite 150 first impressionsI noticed that when I would shade a module and watch its input voltage
go down to find the new MPP V and then remove the shading, it took almost one minute before it started to bring its input
voltage back up again.
May be that is because it's better to sit lower in case a new cloud comes in and loose very little while doing so. Otherwise, when a new cloud appears and it gets darker and darker, you're bound to chase the MPPT point from above and loose a lot. Favoring low side in a volatile environment looks like a good idea to me.As far as solar tracking and lower hardware efficiency being better, that's exactly what we found in side by side comparisons with
identical (very close) arrays and then swapping them, etc. This was measured using a third party system (JJ's, APRS World logging system)
mtdoc posted the final results of this test in post #94 in this thread earlier. It shows that on occasions XW SCC underperformed Classic by 30%. It is really impossible to achive such an underperformace by sitting below the MPPT point. Clearly, something's gone wrong with the test, such as batteries moved into absorption. Therefore, it is impossible to draw any conclusions from the data. -
Re: Midinite 150 first impressionsMay be that is because it's better to sit lower in case a new cloud comes in and loose very little while doing so. Otherwise, when a new cloud appears and it gets darker and darker, you're bound to chase the MPPT point from above and loose a lot. Favoring low side in a volatile environment looks like a good idea to me.
What firmware do you have in your XW-MPPT60's? It should be 1.05 Build 0006. I have seen no difference in how the MPPT60 tracks as compared to the Classic on identical arrays. I ran my MPPT60 on the larger south-facing array for the first few days. I swapped them and am now running the Classic on that array to compare. My south facing has problems with shading this time of year early in the morning and late afternoon due to the fact that the sun comes up in the NE and sets in the NW. So it's got ambient light but receives no direct sun until the sun gets high enough in the sky.
I have not seen a single difference in how the two controllers handle that. Nor have I seen a difference in what they do when a cloud goes over.
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Chris
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