"PV Cold" reading in MX 60 screen

Discussion about the MX60 Charge Controller

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Morningstarre
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"PV Cold" reading in MX 60 screen

Post by Morningstarre » Tue Jul 07, 2020 9:27 am

Anyone see this before? I just replaced some older solar panels for new 325w panels and wired them up in 2 strings through a breaker box. When I connected them to the MX60 the readout shows "PV cold". I cannot find any reference to this anywhere. Anyone got any ideas please?
I do have voltage on the cables coming in.
Thanks.

raysun
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Re: "PV Cold" reading in MX 60 screen

Post by raysun » Tue Jul 07, 2020 9:45 am

From the MX60 manual:
"PV COLD This indicates that the PV array's open circuit voltage is too high for the controller to safely operate. This should only occur with systems using 72v DC nominal PV arrays in very cold temperatures (below 5°
F / -15°C). The controller will automatically restart operation once the PV array's open circuit voltage falls to a safe level (135v). The amount of time
required for it to reset is dependant on the module type, ambient temperature, and the amount of sunlight directly on the PV array. Normally, the controller will start-up in the morning within a few minutes of the PV array being in direct sunlight. Reconfiguring the PV array for a 48v DC nominal will eliminate this from occurring."

The new panels likely have higher voltage than those that were replaced. The series strings need to include fewer panels.

What is V(oc) of the panels? How are they wired in the array?

Morningstarre
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Re: "PV Cold" reading in MX 60 screen

Post by Morningstarre » Tue Jul 07, 2020 10:50 am

Thanks for your reply.
The VOC is 43.5V. I only have 4 panels in a string, and 2 strings.
I have another pole mount with 6 of these same panels wired together into an MX80 and had no problems with these whatsoever.
I thought these charge controllers were to optimize the voltage coming in?
Last night the voltage would have obviously gone down to the 24V of the system, and then I would have thought would reset when the sun came up.
Not sure what to do now. Backwoodssolar said that this configuration would work fine.
?
Thanks again

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Re: "PV Cold" reading in MX 60 screen

Post by EA6LE-ONE » Tue Jul 07, 2020 11:00 am

the MX60 can handle up to 150VDC from PV. You need to have the strings of 3 panels or 2. but if your system is on 24V then you need another MX60 to hadle 8 of 325W panels. So best is: 2 strings with 2 panels each per MX60.

raysun
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My RE system: Flexpower Two: (2) FXR3048A, (2) FM80, MATE3s, FlexNetDC
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Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: "PV Cold" reading in MX 60 screen

Post by raysun » Tue Jul 07, 2020 11:29 am

Morningstarre wrote:
Tue Jul 07, 2020 10:50 am
Thanks for your reply.
The VOC is 43.5V. I only have 4 panels in a string, and 2 strings.
I have another pole mount with 6 of these same panels wired together into an MX80 and had no problems with these whatsoever.
I thought these charge controllers were to optimize the voltage coming in?
Last night the voltage would have obviously gone down to the 24V of the system, and then I would have thought would reset when the sun came up.
Not sure what to do now. Backwoodssolar said that this configuration would work fine.
?
Thanks again
The absolute maximum voltage is 150V, the MX60 displays the PV COLD warning above 135V.

43.5V(oc) per panel? 4 x 43.5 = 174V. Much too high for the rated limit of 150V and the operational limit of 135V.

Morningstarre
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Re: "PV Cold" reading in MX 60 screen

Post by Morningstarre » Tue Jul 07, 2020 2:54 pm

THANK YOU very much. I will change this and report back.

Morningstarre
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Re: "PV Cold" reading in MX 60 screen

Post by Morningstarre » Wed Jul 08, 2020 6:11 am

Hi again.
I split 4 panels into 2x2 and wired them in parallel and series and they are now in use. Ordered another MX80 for the remaining panels.
Thanks again :grin:

raysun
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Posts: 2951
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: "PV Cold" reading in MX 60 screen

Post by raysun » Wed Jul 08, 2020 7:11 am

Good to hear!

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