Temperature in controller shed

[asdex]

Hi, I notice when my controller is running at high current (60A) and the fan is going the temperature in the shed can be up to 30 deg when it's about 26 deg outside. This is measured with the remote temperature sensor normally on the batteries. i put the sensor just below the Classic intake vents at the bottom of the case.
Would 30 deg (C) be a bit hot and decrease the life span of the controller? I could add a 24 volt extract fan if necessary that would come on with my aux relay.
Thanks,

[Vic]

Hi asdex,

IMO,  30 C is not hot.   Fans running on Classics is common.   Those fans are high quality ones,   and are primarily used to keep the temperatures inside the Classic roughly equal.

Having a relatively lower input voltage to the Classic will help to minimize its heating.

What is the nominal string Vmp to this Classic?

Vic

[dgd]

Asdex,

30oC ambient is warm, right now in West Auckland its 27 outside and at back of my garage, under house, its just on 26 where batteries, controllers etc are located. Later today, early evening that will get up to over 30 and stay that way until well after midnight.
You should look at the Classic's internal temps, FET and PCB.
FETs often run mid fifities here and pcb over fifty if output current exceeds 60Amps. Fans are usually going in Classic to bring temps down below 50.

This is all within normal operating range of Classic so I would not expect any problems or dramatic life shortening. I'd get some natural inflow in your shed, vents on roof and lower walls, additional fans inside will only push the hot air around

dgd

[tecnodave]

Just for comparison,


I have two systems side by side,

#1.    Classic 150,   1980 watt bank of 12 Sharp NE-165 wired 3S 4P   Combiner to Classic >260 feet! 8ga. Wire
#2     Classic 150.    2000 watt bank of 8 sharp NE-165 &4 Sharp NE-170 wired 2S 6P combiner  to Classic < 15 feet 10 ga wire

System 1 VMP 105 v.  System 2 VMP 70 v.

Classic one works much hotter, fans run twice as much.  It makes a Hugh difference!  Winter here so my temps are much cooler  batts at 9 deg. C.  FET's 45-48 deg C.  Systems in unenclosed shed , plenty of ventilation.    More than 12 SQ ft vent both ends of shed.

This is temporary as I am building new house here so panels are put out of the construction zone hence the loooong run on system one.......way over recommendation!  The Classic is paying the price for that!

td

[asdex]

Thanks, I have added a roof top vent which is a meter of 150mm flue and a top hat from a woodburner.
The string VMP is 73.82 volts calculated on the Midnite sizing tool.I have seen 84.3 volts on the screen though.
Thanks,

[lsunell]

I just replaced a couple of Xantrex solar controllers with a Midnite classic 150 so I' new to this equipment. I have 2500 watts of solar connected for an open circuit voltage of 116 volts and a 1760 AH battery bank at 24 volts. The FETs are running as hot as 70 C when I am generating 1800 watts and the input voltage falls as low as 72 volts @ 60 to 70 Amps. I read elsewhere on this forum that the FETs shut down at 80 C. Is there a way to help cool this unit down. Would it help to configure the battery bank to 36 or 48 volts? Are there any covers that can be removed to assist cooling

[mike90045]

>  I just replaced a couple of Xantrex solar controllers with a Midnite classic 150 so I' new to this equipment. I have 2500...

I thing the big problem is the panel voltage is WAY more than 2x the battery voltage.   The larger the differential from PV to battery voltage, the hotter things run. 
So, if you do not have mile long runs from the array to the controller, and can re-configure the array to maybe half the voltage it currently is (60V is more than enough to charge a 24V bank) that would reduce the heat.   Wire gauge from the array to the controller is also a factor.   Or maybe it's easier to get a 48V inverter and solve the heat issue that way!

[zoneblue]

You dont say what your ambeint is. Yes, high input voltages should be avoided unless your cable length is really nasty. Your also running that classic farily hard with 2500Wp.  While the classic is fully able to limit and self protect from all these conditions, well as you found out, it will get hot. You can try adding an external fan, which is what others do. Either on 24/7, or triggered using Aux1 when needed. Would recomend either going to strings of 2 panels for 24V, or strings of 3 for 48V. And yes 48, will halve your current and make things much better.

I just replaced a couple of Xantrex solar controllers with a Midnite classic 150 so I' new to this equipment. I have 2500 watts of solar connected for an open circuit voltage of 116 volts and a 1760 AH battery bank at 24 volts. The FETs are running as hot as 70 C when I am generating 1800 watts and the input voltage falls as low as 72 volts @ 60 to 70 Amps. I read elsewhere on this forum that the FETs shut down at 80 C. Is there a way to help cool this unit down. Would it help to configure the battery bank to 36 or 48 volts? Are there any covers that can be removed to assist cooling

[lsunell]

I am in Costa Rica so the ambient temperature is consistently 30 c. I have a Xantrex XW4204 inverter/charger so I'm stuck at a 24 volt battery bank. Looks like a re-wire of the solar panels is in order. 24 volt panels so would two in series for a open circuit voltage of 60 volts be a good match for the 24 volt battery bank? Thanks for the help with this.

[zoneblue]

So 30C ambeint, ...35C in the shed?  If so, might look at how you can improve ventilation in there.

Yes pairs of either 60 cell panels is about as good as it gets for 24V bank. Your gona lose some watts here or there, but situations like yours better in teh cable than in the controller.

Reconfiguring that will provide a decent drop. After that if you still have issues, you can try setting some current limiting.

[offgridQLD]

Forget cooling the room fix the issue  with the high input voltage and it will go away. Just drop the PV input voltage way down. It's cooking its self with at that input voltage with a 24v battery.

I don't know why this potentially negative effect isn't mentioned in the User manual for the classics.

Something like.....(just my way of saying it).

While the classic is capable of charging a battery as low as 12v from a input voltage as high as 150v. More heat will be generated inside your controller if this voltage differential is excessive.

(then the line that wouldn't get the tick from marketing department)
The controller will run hot, fans will run excessively and overall it will shorten the life of the product in comparison to lower voltage differentials. You need to strike a balance between efficiency loss (heat) in your input cables and efficiency loss (heat) in your controller.

I know I would rather loose (try and dissipate) 40w of heat in 50 foot of cable than 40w of heat in a tiny aluminum box full of heat sensitive electronic components.

Then perhaps some kind of graph showing the efficiency loss at several voltage points above the required charge voltage.

I sure wish i was informed befor I wired one of my classics as with strings of 3s and had to deal with a hot controller. Even in a refrigerated (air conditioned) power room that 4200w at 3s (about 125v on a 48v bank)  That Classic was working hot and fans always running. It was a BIG job rewiring that array back to 2s but worth the effort and the fans never run now.

Not having a dig just. I think this issue is something a lot of people could avoid if it was mentioned in the user manual. If for what ever reason people read it and look at the graph then still decide to charge there 12v battery with 150v input then at least they were informed of the negatives of doing so and only have them self to blame then if they need to reconfigure there entire array.

Kurt

[zoneblue]

Agreed. +1 for including that in the manual. Of course from a marketing perspective it kinda contradicts the "point" of high voltage controllers, and to a lessor extent mppt.  Id really like to see a full set of efficiency curves, to enable users to make good decisions about their array configuration.

Also watching electodacus's forthcoming 3kW PWM controller with interest. It seems to me that for a given array that the MPP remains in a fairly tight band, and with 72 cell panels being readily available, PWM might even make some kind of come back.

However, Morningstars curves, in terms of DC converter efficiency (which you have to admit are quite exceptional)  show clearly that the difference between 98V into 12V, and 98V into 48V is a whole 5 percent. 5% of say 2000W is 100W. Thats a LOT of heat for a small box.

[russ_drinkwater]

I used the sizing tool before I did any panel connecting and it was spot on! As the panels only have a 31.2 voc it was not enough after loses to do the equalize on the 24 volt battery bank.
On a good clear warm day voltages are always just under 60 volts.
But I have noticed that even during heavy cover (cloud and rain) we have usable amps inputs with only 1760 watts of panels up.
What is the factory amps outputs default for the 150's set at?

[offgridQLD]

Hi Russ,
            From memory it's 86A on my classics running 48v.

I run lithium batterys so don't need high voltages for EQ. 56v (28v if it was a 24v system)  is as high as I need to go on a daily basis with lithiums. Two series PV works perfect at around 65-80v depending on load and temp conditions it's more than enough to get the job done.

The thing is if you lower the input voltage you will have more loss in the cables but only at full output. If you increase the input voltage you will have heat in the controller at all output levels. In fact it's actually worse under light load.

Most offgrid systems spend most of the day at partial output (unless PV is on a tracker) even then in areas with good sun conditions and large arrays the systems spend a lot of the day  just covering loads in float. So  you wont see the efficiency loss in the cable as the amps are low.

I like MPPT controllers and I do see there is some advantages. Though I don't think they are a reason to ignore good practices when trying to match your PV voltage  to your batterys highest necessary charge voltage. Doing so has benefits that shouldn't be overlooked.

Kurt

[mike90045]

Another +1 for adding a PV voltage / Bat Volt Efficiency chart & note in the manual.