Hi Guys.

 

I need assistance please, I have just bought a DEYE 8kw inverter, 12 x  JA 450 W panels, 4 x 100 ah lithium batteries, i also have a 6 string combiner box with 1 string out. I can convert this to dual if needed.

I am planning to use 4 strings of 3 panels connected in series, with obviously a single string to the inverter, is this the right way to go?

2nd question I have is, will a single input from the combiner box connected  into the inverter be acceptable and still within the inverter tolerances for a single MPPT?

 

Please excuse my ignorance. Advice would be appreciated 

Hi JohanO

As far as I can deduce from what you have given. This what I can suggest.

As you have 12 X JA 450 W panels.

Each panel has an output of  Voc 49,7v and 10.44A max.

I would have 2 strings X (6 x panels in series) on the input of the Deye inverter. (2 X inputs)

It is better to use only 2 strings as the start up voltage is 150V (the voltage the unit is able to utilize the power input from the panels).

If you use only 2 strings it allows you to utilize the power at a lower level on cloudy days. With 3 panels in series you output at the best sunlight is less than 150V (41.42V x3= 123,6V for each string).

In short this means you would not be able to utilize the pv panels to get the best power input to the 8KW Deye if you use 4strings x (3 panels in series).

You can put up to 425Voc (Volts open circuit) max and 9Amps max on each input. As you can produce slightly more amps it really does not matter and if you do the unit will only utilize 9amps. I think some updated units allow slightly more amps to accommodate bigger panels.

This would be 298.2 Voc (volts open circuit) and 10,44A max for each series string which is well within the specification. 

You should not connect any panels in parallel as each panel is already at the input current limit.

You will not need any combiner boxes if you connect panels in series.

I hope this explanation helps. 

Edited January 1, 20223 yr by Peter Topp

1 hour ago, JohanO said:

Hi Guys.

 

I need assistance please, I have just bought a DEYE 8kw inverter, 12 x  JA 450 W panels, 4 x 100 ah lithium batteries, i also have a 6 string combiner box with 1 string out. I can convert this to dual if needed.

I am planning to use 4 strings of 3 panels connected in series, with obviously a single string to the inverter, is this the right way to go?

2nd question I have is, will a single input from the combiner box connected  into the inverter be acceptable and still within the inverter tolerances for a single MPPT?

 

Please excuse my ignorance. Advice would be appreciated 

Here is the inverter specs.

Thank you for the reply, I have tried connecting 6 panels in series in a single string, however it gives me an F23 fault every time, when I reduce it to 3 panels in series, the warning disappears, 

 

F23: THE AC leakage current is trancient over current.

What could that be?

Hi JohanO

I have quoted you the specs of the  Deye Kw inverter needed for the pv panels . Here it is in detail.

PV String Input Data

• Max. DC Input Power (W): 10400W.
• PV input Voltage (V): 370V (100V-500V).
• MPPT Range (V): 125-425V.
• Start-up Voltage (V): 150V.
• PV Input Current (A): 22A + 22A.
• No. of MPPT Trackers: 2
• No. of Strings Per MPPT Tracker: 2+2.

.

That is correct, it has the same label on the side of the inverter.

Hi JohanO

Fault 23 means you have a current leak before the unit either a short circuit or arching. You would have to check your cabling from the pv's to the unit for cracks. If you have surge arrestors connected they will also have to checked.

The cable can also be checked with a megger when the cable is disconnected from the panels and Deye unit.

It might be easier just to replace the cable.

Does this happen to both series strings or just one? You can test one at a time. 

Edited January 1, 20223 yr by Peter Topp

Thank you, I will check it, I tried to double check and  used the same cable that runs from PV to inverter on the 3 panels in series, no problem, however connecting 3 extra panels on the same wire immediately  results in error F23 is given. The same error on bank of 6 other panels.

I have no surge arrestor connected currently, when I check the cable on the inverter side with 2 strings x  6 panels connected in series the voltages on both strings run almost identical outputs

Hi JohanO

If there is a crack in the insulation the higher voltage when the 3 extra panels can show up as a problem.

This how I would check the problem.

1) Check the second string of 6 panels in series separately on another input if no problem continue.

2) Check the second string of 6 panels in series separately on the input where fault shows up if no problem continue.

3) Check cables of fault stings  and repair or replace cable.

If in step 1  or step 2 you have a problem you need to check  and repair or replace all cables if this does not solve the problem you will need to have the Deye unit checked.

Hi JohanO

Just a word of caution when checking. With the high voltage produced during sunlight arching can occur and you can be burnt or get a shock. I hope you have some sort of isolation when you swap inputs or work on the unit.

Thinking about the problem a single faulty pv unit can also cause the problem if shorted to earth.

Edited January 1, 20223 yr by Peter Topp

Thank you, I will definitely be very careful,  none of the PVs are not currently earthed, something I stiill have to do...

 

I will run new cable tomorrow, leaving them in sets of 3, if that works as it should I will start connecting 6 together