Thoughts on Midnite Classic 250

OffGridForGood said:

East and West array point the equipment box end North to avoid some of the direct sun to minimize heat gain on the equipment.

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They're pointed North for that reason, but a flat array still outperfoms E/W since it's not overpaneled. There may be some situations where two trailers go to one controller, and in that case will definitely E/W both trailers.

I purchased a CL250 from a DC Solar trailer and ended up purchasing a new one. Its been the heart beat of my system.
Quote from Midnite:
We sold very few full-featured classics to DC Solar and that was about 4 years ago so it's doubtful you have the full-featured model. A quick way to know is to look for a colored dot sticker or the -Carpoff sticker on the box. But that aside if you get me a serial # I can look it up

There are a few threads @ Midnite on these trailers & the Classic-250's (not the normal ones you buy retail) and it would be prudent to look on THEIR Forums for more info... there is a wealth of it there.

I have a Classic 200 & 150. They are great and do exactly as they are supposed to BUT these are Retail Models and not even the SL edition. Their fans ARE loud & annoying but as others have said they have a kit for that. The replacements are not any quieter - damned shame they didn't use fans with ball bearings as opposed to the cheapo's with sleeve bearing that make noise.

FYI: The US Army is about to start dumping similar trailers so keep an eye out. Additionally, the US Forces have to replace all of their LFP Battery Packs (They are made by CATL) - DUKE Energy is already swapping them out, they started in December. There will be some damned good deals there folks.

sunshine_eggo said:

They're pointed North for that reason, but a flat array still outperfoms E/W since it's not overpaneled. There may be some situations where two trailers go to one controller, and in that case will definitely E/W both trailers.

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I wonder in this situation if it would be best to strip all the parts from those 8 trailers, build new ground mounted PV to get the most from the panels, add more panels where this makes sense, sell the trailers to pay for the ground mounts and parts needed, and build a few solar sheds. Just an idea to explore.
One thing about trailer mounted anything, they can disappear on ya.

Steve_S said:

There are a few threads @ Midnite on these trailers & the Classic-250's (not the normal ones you buy retail) and it would be prudent to look on THEIR Forums for more info... there is a wealth of it there.

DC Solar Trailers MPPT-250

DC Solar Trailers MPPT-250

midniteftp.com

I have a Classic 200 & 150. They are great and do exactly as they are supposed to BUT these are Retail Models and not even the SL edition. Their fans ARE loud & annoying but as others have said they have a kit for that. The replacements are not any quieter - damned shame they didn't use fans with ball bearings as opposed to the cheapo's with sleeve bearing that make noise.

FYI: The US Army is about to start dumping similar trailers so keep an eye out. Additionally, the US Forces have to replace all of their LFP Battery Packs (They are made by CATL) - DUKE Energy is already swapping them out, they started in December. There will be some damned good deals there folks.

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Thanks for that!

OffGridForGood said:

I wonder in this situation if it would be best to strip all the parts from those 8 trailers, build new ground mounted PV to get the most from the panels, add more panels where this makes sense, sell the trailers to pay for the ground mounts and parts needed, and build a few solar sheds. Just an idea to explore.
One thing about trailer mounted anything, they can disappear on ya.

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That *might* be an option. They are on 25 acres with secure/locked fence all around and freshly installed security cams everywhere. They live only about 10 minutes from the site, so they can get there fast, and they are your typical Arizonan with regards to 2nd amendment enthusiasm. They are working through a zoning issue that's preventing them from launching a business. I suspect once this resolves, and they have a path forward, they'll be more willing to budget for infrastructure.

Right now, it's just about getting minimum workable systems to four different locations across the property. The trailers make sense for now.

The Midnite Classics are, honestly, pretty well bulletproof! We literally have hundreds of them out and I could probably count on my 2 hands how many failures we have had! Now I will say that we did not use many of the 250s. Mostly the 200s and some 150s.

The 250s are limited too much on charge amps (?~65A?), while the 200 does 79A and you can string 60 cell panels 4S and 72 cell panels 3S comfortably. The 150s will do 90A+, but 150V limit makes it not very nice to string newer 72 cell (or split cell/144 cell) panels. Something to keep in mi9nd is that while the Classics have HyperVOC, they actually stop producing when in that HyperVOC voltage range (nameplate voltage plus battery voltage, e.g. 200v nameplate + 53V batt = 253VDC with no damage to unit). In northern (colder) climates you will hit HyperVOC sometimes during the winter if you string 4S with 60 cell panels or 3S with 72 cell panels, on a Classic 150.

Long story short, over the years we have found the CL250s to be the sweet spot on Voltage vs. Amps.

The SLXXX versions have the exact same hardware (except for the ethernet jack being missing on the PCB) as the full featured ones..... just software differences. No hydro or wind options. Solar only. The idea was to make a unit that is cheaper, but just with less features. IIRC the SL units also don't support using the Whizbang Jr shunt for battery SOC monitoring.

When the Classic fans give out, the unit derates it's PV production to keep the temp down. Fans are very easily replaced!

We had one unit fail (this was a CL200) when we accidentally didn't have the battery side negative connected to a negative busbar correctly and it got against a grounded switchgear frame. I'm assuming it toasted the ground fault circuitry, but haven't gotten around to calling Midnite yet to get it fixed.

Moral of the story is that I would pretty well trust the Midnite Classic CCs with my life! (Not quite... just very close.... LOL)

CL250s are limited to 55A on 48V systems.

Using the second user's numbers, the failure rate is 7 out of 18 total (2 of 8 trailers and the other user has two trailers + 8 other CLXXX controllers).

1. Were all the trailers built at the same time? Bad run of chips?
2. They are just working outside their intended specifications.

sunshine_eggo said:

CL250s are limited to 55A on 48V systems.

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You are right, I couldn't remember exact numbers. Here is their curve sheet:



And here are the ones for the 150 and 200:

sunshine_eggo said:

Using the second user's numbers, the failure rate is 7 out of 18 total (2 of 8 trailers and the other user has two trailers + 8 other CLXXX controllers).

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That is some pretty terrible numbers! I would lean heavily toward there being some kind of installer error, going off of my own background with them! Although my experience is much more with the CL150 and CL200! So it could be that the CL250 is not as reliable, although we do have some of those out there as well, and I believe we had one whole one fail. But I'm pretty sure that was when it got toasted by lightning!

Is there any chance of lightning strikes playing into these failures? Any way that being on a trailer is attracting stray voltage or lightning and causing issues? What about grounding, is there any grounding? (I assume not really, if it's trailer...?)

Our installs are virtually all in permanent/ stationary installs. E.g. not on trailers....

I know Midnite has told me before that it is always cheaper to fix the Classics, rather than to replace them. But I know you are thinking replace with a CC that you have more trust in lol. I don't remember seeing the specs of the panels that are on these units. Would it be possible to swap out to a CL200? Maybe too high PV voltage string for that... (But then again, I know you are comfortable with Victron, so swapping to a Victron probably makes more sense to you.)

I see @Steve_S posted a nice graph with a Classic comparison.

Cmiller said:

That is some pretty terrible numbers! I would lean heavily toward there being some kind of installer error, going off of my own background with them! Although my experience is much more with the CL150 and CL200! So it could be that the CL250 is not as reliable, although we do have some of those out there as well, and I believe we had one whole one fail. But I'm pretty sure that was when it got toasted by lightning!

Is there any chance of lightning strikes playing into these failures? Any way that being on a trailer is attracting stray voltage or lightning and causing issues? What about grounding, is there any grounding? (I assume not really, if it's trailer...?)

Our installs are virtually all in permanent/ stationary installs. E.g. not on trailers....

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10 in trailers, 8 stationary. I can't comment on the non-trailer installations.

Cmiller said:

I know Midnite has told me before that it is always cheaper to fix the Classics, rather than to replace them. But I know you are thinking replace with a CC that you have more trust in lol. I don't remember seeing the specs of the panels that are on these units. Would it be possible to swap out to a CL200? Maybe too high PV voltage string for that... (But then again, I know you are comfortable with Victron, so swapping to a Victron probably makes more sense to you.)

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5S 60 cell panels, 189Voc, so a 200 is pretty marginal. This is the Phoenix area, but we can get below freezing.

The only way I'd consider retaining the CL250s is if the repair cost is minimal, but it's ultimately up to the user.

Classics have HyperVOC unlike other SCC's. A Classic 250 CAN take up to a MAX of 298V, while a CL-200 can take 248V. Of course that is for a 48V Battery System.

I do hit VOC with my C-200 and never a blink cause I am just a "tad" under (2 volts actually, talk about close).
C-200 has 4S2P config with Canadian Solar 260W Poly panels.
C-150 has 2S3P config using Q-Cell 395W HJIT Panels (MAN they are great with Shade & Cloud)

Steve_S said:

Classics have HyperVOC unlike other SCC's. A Classic 250 CAN take up to a MAX of 298V, while a CL-200 can take 248V. Of course that is for a 48V Battery System.

I do hit VOC with my C-200 and never a blink cause I am just a "tad" under (2 volts actually, talk about close).
C-200 has 4S2P config with Canadian Solar 260W Poly panels.
C-150 has 2S3P config using Q-Cell 395W HJIT Panels (MAN they are great with Shade & Cloud)

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Yeah. HyperVOC is a cool feature.

sunshine_eggo said:

5S 60 cell panels, 189Voc, so a 200 is pretty marginal. This is the Phoenix area, but we can get below freezing.

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Yea, I wouldn't use that on a CL200. Too close to that voltage rating!

Steve_S said:

Classics have HyperVOC unlike other SCC's. A Classic 250 CAN take up to a MAX of 298V, while a CL-200 can take 248V. Of course that is for a 48V Battery System.

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The issue with HyperVOC (that most people don't realize) is that while the voltage is in that HyperVOC range, the Classic stops producing power! It's pretty cool that it gives it more "headroom", but then when you have had 2 weeks of no sun in the winter and you get a cold bright day, and the Classic sits in HyperVOC and isn't producing, you wish for a higher voltage controller, or to have the panels stringed differently!

Back in the day we did a few installs with CL150s and 4S2P with 235W panels. Then the customers started calling us on cold, clear winter days, asking why the CC says HyperVOC and isn't charging.... That's when we switched to the CL200s for those setups!

There are some number of folks on this and other forums who have or want to get a bunch of solar gear into a trailer-mounted scenario, myself included.

Anytime anything gets onto a trailer, and if used for any terrain scenario other than highway and perfect asphalt (no potholes), I'd expect a shortened lifespan. My guess is these DC Solar trailers took, and are probably still taking, a beating anytime they move. It's a hard life on open terrain. I'm still pondering how to get a number of typical pieces of equipment to survive the terrain around my measly 40 acres.

If you have a chance, @sunshine_eggo, a few pics of what DC Solar did to perhaps make this equipment survive trailer-mounting would be appreciated. If there's no special cushioning arrangement, and they just relied on the trailer suspension, I'd think that to be a smoking gun.

Take the normal lifespan of anything, and derate by 50% or more for trailer-mounting. Add in the "jarred-loose" wires, connectors, and the all-important "ground connection wire" (not having a lock washer), and it's another downtime % for the diagnostics.

Of course, anytime we buy anything used, we are just buying other folk's problems, and we'll never know fully what they were (leading to the sale) ... perhaps the best use for such items is to either part it out, or plan on pulling everything off and rebuilding it (bionic man fashion).

sunshine_eggo said:

I have always regarded Midnite as Tier-1, and they have a good reputation. I now have concerns.

I have encountered an outfit that purchased 8X DC-Solar trailers, and I am helping them figure stuff out - what works, what they need, etc. On at least 2 of them, the Classic 250s have failed. One turns on, boots up, shows the display, but it shorts the PV circuit. The other simply makes a buzzing sound with nothing on the display when battery power is applied. I have confirmed with Midnite Support that these are failure conditions.

MNPV6 boxes are used to provide both the PV and battery breakers.

Of the inverters I have looked at on these trailers, the longest on-time unit is about 20,000 hour. This is the equivalent of 2.5 years of continuous use. I think it's reasonable to assume the MPPT operated for the same period of time.

This is a 25% failure rate in 2.5 years of operation on units that are likely about 8 years old. That's not encouraging.

This user has also been in contact with another user that has several trailers. According to them, they had to replace three failed units (not sure of the percentage).

I am concerned that the Classic 250 is not as reliable as one would infer from their reputation.

Considerations:

1. These installations are pretty brutal, i.e., metal boxes that live outside with questionable ventilation next to two big SMA 6kW inverters.
2. They are actively cooled with fans. If the fans fail, I suspect the units would eventually fail. Not necessarily a quality issue, but a potential vulnerability.

Midnite indicated a $200-275 typical repair cost (can be much lower and much higher) with a 6 month warranty on repairs. Unfortunately, the 250 is limited to 55A output on a 48V system, which puts even the repair cost at a premium. I am much more inclined to install a Victron 250/100 MPPT for $625 or so rather than pay the typical repair cost.

$625 for 100A MPPT with a 5 year warranty and passive cooling.
$475 for 110A MPPT with a 6 month warrant and active cooling.

I'm sure there are a lot of people out there who can say "I've had mine for 15 years, and it works great." I'm just wondering if these aren't the best choice for this installation type.

Thoughts?

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In my case, (a cheap secondhand as-is Classic 150) the PV voltage being dragged down to 0v was a result of a few shorted FETs. $2.50 each from Digikey. I considered replacing them with FETs with 200V breakdown, but stuck with the originals.


Check Midnite forums if considering the repair. There are a few other things to check such as gate drivers.

The FETs are a PITA to remove, but other than that, a simple process.

Exceeding VOC+hyperVOC on the PV input is a way to blow the FETs. I understand this can happen to wind and hydro users if they don't have a clipper to regulate voltage, or if it fails.

Assuming the Classic starts up, there is a way to dump the internal registers which may give some hints on what was happening immediately before failure (excessive input voltage?)

Like many others, my primary CC is a Classic 150. For almost 10 years and it has been a workhorse. However it lives a charmed life compared to the trailer units... it is mounted on a wall in a cool, relatively dust-free location protected from the elements.

Mof said:

Exceeding VOC+hyperVOC on the PV input is a way to blow the FETs. I understand this can happen to wind and hydro users if they don't have a clipper to regulate voltage, or if it fails.

Assuming the Classic starts up, there is a way to dump the internal registers which may give some hints on what was happening immediately before failure (excessive input voltage?)

Like many others, my primary CC is a Classic 150. For almost 10 years and it has been a workhorse. However it lives a charmed life compared to the trailer units... it is mounted on a wall in a cool, relatively dust-free location protected from the elements.

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Unfortunately, there are a few members here who tell people it is OK to exceed the Max Limits and they say because they'll clip the power, which they will until all of a sudden POOF and they stop working. Midnite's HyperVOC is a saver but again only when within Midnites specs & limits (just like others). Some enjoy being Brave with other people Money & Lives.

Steve_S said:

Unfortunately, there are a few members here who tell people it is OK to exceed the Max Limits and they say because they'll clip the power, which they will until all of a sudden POOF and they stop working. Midnite's HyperVOC is a saver but again only when within Midnites specs & limits (just like others). Some enjoy being Brave with other people Money & Lives.

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They will clip the "power", but volts and power are not equal. They can't clip the voltage. Too much overvoltage will pop components every time. And the other thing is, when the Classics are in "HyperVoc" state, they are NOT PRODUCING POWER! HyperVoc is actually a "protection state". (My own description.)

Personally, I feel that little bit of power clipping under good solar conditions shouldn't be any issue. The Classics have cooling fans, and they self limit to the point that if the cooling fan is not working they will self limit charge amps to drop their internal temp! I have seen this! But I would never recommend that someone installs a string of panels that will from time to time run into the "HyperVoc zone". That causes power loss due to shutdown, and runs a risk of overvolting and popping components!

Steve_S said:

Unfortunately, there are a few members here who tell people it is OK to exceed the Max Limits and they say because they'll clip the power, which they will until all of a sudden POOF and they stop working. Midnite's HyperVOC is a saver but again only when within Midnites specs & limits (just like others). Some enjoy being Brave with other people Money & Lives.

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I haven't seen the schematic and Midnight hasn't described in detail.
But my pondering on the function came up with the patently obvious answer that if FET switches, inductive kick applies Voc across the FET.
If FET doesn't switch, FET only experiences Voc - Vbat. That is actual Vbat at that instant, not 48V nominal or the like.

Therefore, if battery is disconnected and output of Midnight Classic is looking into inverter input capacitors with zero volts, FET sees Voc "Vbat" = 0V for HyperVoc purposes.

Lithium BMS or battery disconnects switches/breakers could trip it up.

sunshine_eggo said:

I have always regarded Midnite as Tier-1, and they have a good reputation. I now have concerns.

I have encountered an outfit that purchased 8X DC-Solar trailers, and I am helping them figure stuff out - what works, what they need, etc. On at least 2 of them, the Classic 250s have failed. One turns on, boots up, shows the display, but it shorts the PV circuit. The other simply makes a buzzing sound with nothing on the display when battery power is applied. I have confirmed with Midnite Support that these are failure conditions.

MNPV6 boxes are used to provide both the PV and battery breakers.

Of the inverters I have looked at on these trailers, the longest on-time unit is about 20,000 hour. This is the equivalent of 2.5 years of continuous use. I think it's reasonable to assume the MPPT operated for the same period of time.

This is a 25% failure rate in 2.5 years of operation on units that are likely about 8 years old. That's not encouraging.

This user has also been in contact with another user that has several trailers. According to them, they had to replace three failed units (not sure of the percentage).

I am concerned that the Classic 250 is not as reliable as one would infer from their reputation.

Considerations:

1. These installations are pretty brutal, i.e., metal boxes that live outside with questionable ventilation next to two big SMA 6kW inverters.
2. They are actively cooled with fans. If the fans fail, I suspect the units would eventually fail. Not necessarily a quality issue, but a potential vulnerability.

Midnite indicated a $200-275 typical repair cost (can be much lower and much higher) with a 6 month warranty on repairs. Unfortunately, the 250 is limited to 55A output on a 48V system, which puts even the repair cost at a premium. I am much more inclined to install a Victron 250/100 MPPT for $625 or so rather than pay the typical repair cost.

$625 for 100A MPPT with a 5 year warranty and passive cooling.
$475 for 110A MPPT with a 6 month warrant and active cooling.

I'm sure there are a lot of people out there who can say "I've had mine for 15 years, and it works great." I'm just wondering if these aren't the best choice for this installation type.

Thoughts?

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We just purchased a DC Solar Trailer (full options) and I will need to replace the panels and I am considering an EG4 CC 500VDC/100Amp ... not definite just yet but what are the differences between Victron and EG4?

Hedges - for those of us who are nowhere near being experts at these trailers - instead of laughing how about some insight. Some of us are asking for direction - not ridicule.

Snort! (wipes away tears)

We read many complaints about EG4 products here on the forum.
Although in fairness, they sell a large volume, so we're mostly hearing from the squeaky wheels.

Victron is generally considered to be high quality.
But some people have reported problems.

If you would be connecting to the grid or otherwise will have permits/inspections, UL Listing matters. Victron has a couple listed products, but mostly is for mobile applications, and European applications.

EG4 has several listed products. (And people report successfully using their PowerPro with Sunny Island.)

Midnight is regarded as very good. Besides the Classics used on these trailers, they have a couple new ones, Hawkes Bay and Barcelona. What you want will depend in part how big a PV array you will connect.

The trailers had fairly small PV arrays, not enough to properly charge lead-acid batteries. If you're replacing with Lithium, then low charge rate is acceptable. Make sure the SCC you select has either Lithium settings (adjustable) or VRLA settings that will meet the needs.

I'm a fan of SMA. I would be inclined to connect a Sunny Boy GT PV inverter, probably an older model especially if not backfeeding the grid. Be sure to get one on SMA's compatibility list. I try to pay $0.10/W for old stock Sunny Boys.


With AC coupled GT PV, the Sunny Island on the trailer serve as charge controllers, about 11kW for the two. Can either use VRLA settings or select models of battery/BMS for closed-loop. The PV and Sunny Boy wattage add to loads you can power during the day.

Hedges said:

Snort! (wipes away tears)

We read many complaints about EG4 products here on the forum.
Although in fairness, they sell a large volume, so we're mostly hearing from the squeaky wheels.

Victron is generally considered to be high quality.
But some people have reported problems.

If you would be connecting to the grid or otherwise will have permits/inspections, UL Listing matters. Victron has a couple listed products, but mostly is for mobile applications, and European applications.

EG4 has several listed products. (And people report successfully using their PowerPro with Sunny Island.)

Midnight is regarded as very good. Besides the Classics used on these trailers, they have a couple new ones, Hawkes Bay and Barcelona. What you want will depend in part how big a PV array you will connect.

The trailers had fairly small PV arrays, not enough to properly charge lead-acid batteries. If you're replacing with Lithium, then low charge rate is acceptable. Make sure the SCC you select has either Lithium settings (adjustable) or VRLA settings that will meet the needs.

I'm a fan of SMA. I would be inclined to connect a Sunny Boy GT PV inverter, probably an older model especially if not backfeeding the grid. Be sure to get one on SMA's compatibility list. I try to pay $0.10/W for old stock Sunny Boys.

https://files.sma.de/downloads/SB-OffGrid-TI-US-en-23.pdf

With AC coupled GT PV, the Sunny Island on the trailer serve as charge controllers, about 11kW for the two. Can either use VRLA settings or select models of battery/BMS for closed-loop. The PV and Sunny Boy wattage add to loads you can power during the day.

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Hedges - oh - no argument from me scratching my head on the panels!! LOL! I wanted the platform because we are building atop a mountain in Northern Nevada (no grid tie available unless we pay 60k!) I appreciate your input! I have heard that Midnite just released a new Charge Controller today. I would upgrade to one of their higher quality units if it matches up to the SMA inverters. I will also accommodate whatever amount of solar array is necessary to keep the FLA's completely charged. This trailer has seen some action and probably been abused from use and then neglect - so I expect it will be a challenge. I would like to get the trailer dialed in so we can move into our RV and power it - even if it is limited power. We are fortunate and have a 220hr (11k) Kubota that is part of the trailer package - so getting a charging system for a battery bank will be able to happen until a new array can be built. I didn't mean to be "snotty"! Sorry if I came off that way. Some of you guys are at the peak of your game in comprehending how to put these systems together on a limited budget - there is always something for us newbies to learn if you don't mind sharing your knowledge. Thanks and look forward to seeing posts from you!