Sunnyboy 4000TL twin mppt

[wstevew]

A few days ago I had installed a sunny boy 4000tl inverter. 16 suntech stp240s-20wd panels 8 east and 8 west (2strings) 3.84kWp

The display alternates between strings. But string 2 shows 0v always.

The system has been generating between 1kWh and 3.4kWh per day.

They are going to come out after the mayhem on the 12th.

Would this be they have wired the strings in parallel to one mppt. Or is only one half of the array working. Either way I guess it won't be working efficiently.

Ps there is no shading 1kWh day was cloudy. 3.4kWh day sunny almost all of the day.

 

[screwdriver]

To quickly check if only half the array is working you can turn off one dc isolator at a time and watch what the dc amps does on the display, if it drops a bit then they 'should' be connected and outputting, I would hazard a guess that both cables have been connected into one input zone of the inverter, if you have an east west roof then you defo need both trackers, If you wanted to do the installer a favour and check the connections you can isolate all the switches, pull the dc breaker from the inverter and see if the dc cables are connected to one side only, a pair from each dc isolator should go to the leftmost plugs and then the rightmost plugs. if all 4 are next to each other then it has been plugged into one mppt only. I am not condoning a non technical person to do this ( in case it all goes wrong!) Hope that helps

 

[wstevew]

Thanks for the reply. I insisted I needed a dual tracker when ordering because of the two aspects.

I will try the isolators at the weekend as its barely started when I leave and dark when home.

Strangely on the day of the install they left the west side isolator off. I switched it on.

I think best to leave it to them as its working and want to stay alive. (if inverter wired wrong how do I know isolators wired right)

 

[JohnBoyZ]

If you look at the DC cables from the two array isolators they will enter underneath the inverter, If you can see a pair of cables either side of the solar switch then both inverter inputs are being used used and you should be seeing a voltage displayed for each array shown on the display. If all four cables are on one side of the solar switch then both strings are connected together on one input and voltage will only be displayed for one string. As you have an E/W split I would expect both inputs to be used as they have independent MPP tracking. If its currently wired for both inputs then it could be a bad connection somewhere, it should be an easy fix. I assume you have checked both DC isolators are switched ON!

 

[wstevew]

Thanks.

All on the left side. So 2 strings to 1 mppt.

Hopefully just a mistake.

 

[JohnBoyZ]

Easy fix then, just need to move the 2nd string to the other input, it does seem to be a bit of a basic error by the installer and as you said they didn't even make make certain both isolators were ON before leaving. Sounds like they were keen to get away.

 

[wstevew]

Yes was Friday afternoon!

They have also left on top of each isolator a jumper (short piece of cable with a crimp on each end) not sure why.

So they just need to move them over. Manual mentions sealing plugs.

 

[JohnBoyZ]

Yes was Friday afternoon!

They have also left on top of each isolator a jumper (short piece of cable with a crimp on each end) not sure why.

So they just need to move them over. Manual mentions sealing plugs.

Jumpers might have been used to do short circuit current measurements on the strings and they just left them behind. The inverter comes with a full set (8) of DC connectors that are used to connect the string inputs, in your case only 4 are used and the spare ones are fitted with a small plug that is used to seal the cable entry and then they are plugged into the unused inverter inputs. They will just get repositioned when the strings are connected correctly.

 

[wstevew]

Jumpers might have been used to do short circuit current measurements on the strings and they just left them behind. The inverter comes with a full set (8) of DC connectors that are used to connect the string inputs, in your case only 4 are used and the spare ones are fitted with a small plug that is used to seal the cable entry and then they are plugged into the unused inverter inputs. They will just get repositioned when the strings are connected correctly.

Thanks I can now see what they need to do from the manual.