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Inverter shutdown due to overvoltage from panels in cold temperatures

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  • Inverter shutdown due to overvoltage from panels in cold temperatures

    I have had a problem on bright sunny cold days the inverter shuts down due to the panels voltage exceeding the 580V maximum. Inverter is a Power One Aurora PVI-3600-UK panels are Sunrise Solartech 16x 250 W in 2 strings. I have heard of a unit that can switch off a panel in each array to reduce the voltage when the temperature falls below a preset level. does anybody have any information on this & can I obtain one in UK?

  • #2
    If you switch a panel "off" in a string, you'll pretty much kill the whole output of that string, so even if you can find one, you don't want to use it in your configuration.

    What you DO need to do is simply rewire the strings into 4 strings of 4, assuming that number still meets the minimum voltage to fire up the inverter, or you may need to drop out a panel, and wire 3 strings of five, or you might be able to add 2 panels and go with 3 strings of 6 ( but that may be too much for the inverter, wattage wise, hard to say without specs on panels and inverter ).

    Sounds like somebody failed to take temperature into account when designing your system.


    Edit: Actually, you may just flat have too many panels (4000w) for that inverter if it's a 3600w indicated by the number in it......and that shows up on good cold, clear days when the panels approach max output.

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    • #3
      Yes it is called a single pole double throw thermostat.
      finding one in the DC voltage range is the issue.
      NABCEP certified Technical Sales Professional

      [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

      [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

      [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

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      • #4
        Wired like this
        Attached Files
        NABCEP certified Technical Sales Professional

        [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

        [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

        [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

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        • #5
          Ah, yes....that would just cut out the one panel.

          Good one, Rich !

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          • #6
            Thanks for the information I will see if I can source a suitable unit for the strings, it will need to be weatherproof & with a low temperature range. I found a device from a US company called Apollo Solar but it seems to have been dicontinued not sure why.

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            • #7
              You could just short out a panel; you are losing its output anyway, and
              in cold weather it shouldn't overheat. Then the switch won't need to take
              so much DC voltage switching. Alternately, the switch would be considerably
              stress relieved with make-before-break contacts. Even a big transistor could
              do the job automatically. Bruce Roe

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              • #8
                This must be a common problem where you are maximising the input to the inverter but live in a climate with cold but sunny weather I'm surprised that a temperature sensitive DC switch - thermostat or similar electronic switching device is not more readily available, or inverters with the facility built in or available as a plug in add on.

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                • #9
                  in this case its really a problem of the inverter being undersized for the panels. Its not a good idea to be running 4000w of panels into a 3600w inverter.
                  Thermal switches are not redily available as there is no need for them in a well designed system

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                  • #10
                    Hi John
                    The spec for the inverter clearly states that the maximum input is 4200W which is 200W more than my panels maximum output. It is rare that panels actually produce their specified output 85% is considered the norm, conditions have to be exactly as the test spec to come anywhere near the 100% figure. That said it would be interesting to see what the actual output is in bright sun with an ambient temperature of 5 deg Celsius or less the voltage is high, current? maximum wattage? can it exceed the rated output in these conditions. The Inverter spec shows that the output to grid falls to zero at 580V DC input.

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                    • #11
                      Originally posted by KeithOT View Post
                      Hi John
                      The spec for the inverter clearly states that the maximum input is 4200W which is 200W more than my panels maximum output. It is rare that panels actually produce their specified output 85% is considered the norm, conditions have to be exactly as the test spec to come anywhere near the 100% figure. That said it would be interesting to see what the actual output is in bright sun with an ambient temperature of 5 deg Celsius or less the voltage is high, current? maximum wattage? can it exceed the rated output in these conditions. The Inverter spec shows that the output to grid falls to zero at 580V DC input.
                      Actually I'm surprised you haven't fried your inverter from over voltage. As far as design goes how are the modules configured string wise. what modules and inverter do you have maybe we can come up with a solution. or simply add a Tigo system which will do the same thing and allow for individual monitoring of modules.
                      NABCEP certified Technical Sales Professional

                      [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

                      [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

                      [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

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                      • #12
                        Originally posted by Naptown View Post
                        Actually I'm surprised you haven't fried your inverter from over voltage. As far as design goes how are the modules configured string wise. what modules and inverter do you have maybe we can come up with a solution. or simply add a Tigo system which will do the same thing and allow for individual monitoring of modules.
                        Well............
                        The installation company have just visited & modified the arrangement they seem a bit coy over what they have done they have split the strings & now I have 2 additional cables & a second DC isolator but the were unable to reconfigure the Inverter as the display has blanked so now I get a new inverter tomorrow.... At the moment I am just running on 1 string until the changeover not a problem as the weather is dull & cloudy.
                        The original arrangement was 2 strings of 8 x 250W Sunrise SolarTech (Chinese) monocrystalline panels mounted on a south facing 45 deg roof, inverter is a power one Aurora PVI-3600-UK loft mounted. I have a remote monitor that works from a pulse sensor mounted on my generation meter it is a Solo PV Display manufactured by GEO (Green Energy Options Ltd) it displays the power generating in real time & the total for the day it stores the info on an SD memory card which you can download to their program installed on my PC. A neat unit supplied by my installer as part of the package. This problem is costing them some cash as they had to erect scaffolding to access the roof.

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                        • #13
                          Originally posted by KeithOT View Post
                          Well............
                          The installation company have just visited & modified the arrangement they seem a bit coy over what they have done they have split the strings & now I have 2 additional cables & a second DC isolator but the were unable to reconfigure the Inverter as the display has blanked so now I get a new inverter tomorrow.... At the moment I am just running on 1 string until the changeover not a problem as the weather is dull & cloudy.
                          The original arrangement was 2 strings of 8 x 250W Sunrise SolarTech (Chinese) monocrystalline panels mounted on a south facing 45 deg roof, inverter is a power one Aurora PVI-3600-UK loft mounted. I have a remote monitor that works from a pulse sensor mounted on my generation meter it is a Solo PV Display manufactured by GEO (Green Energy Options Ltd) it displays the power generating in real time & the total for the day it stores the info on an SD memory card which you can download to their program installed on my PC. A neat unit supplied by my installer as part of the package. This problem is costing them some cash as they had to erect scaffolding to access the roof.
                          I just looked up your modules and the only way to get that kind of voltage is to have one string of 16
                          NABCEP certified Technical Sales Professional

                          [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

                          [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

                          [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

                          Comment


                          • #14
                            Originally posted by Naptown View Post
                            I just looked up your modules and the only way to get that kind of voltage is to have one string of 16
                            Very strange they were definitely wired in 2 strings of 8 I do wonder if the inverter had a fault the display has never worked properly. by the same token the installers have had a similar problem with one or two other installations. So I remain puzzled but as the installation is only 2 months old it is up to my installers to fix it.

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                            • #15
                              You need the software disk and a laptop to configure the Aurora at startup to accept the 2 strings and configure the display.
                              I had a PVI 3000 us installed alongside an SMA SB3800 and the daily output was significantly lower than the SMA, so I had my installer swap it out as it was not the inverter that they had specified in my contract. Both strings produced the same out put per day following the swapout.

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