Cable Sizing Assessment

Question 1.1

The distance between the array junction box and inverter is {50} m. The array ISC current is {10} A and the MPP voltage is {520} V.

Choose the minimum cross-sectional area cable you can use, if the resistivity of the cable is 0.0219 Ω/m/mm2 and voltage drop must be kept below 1%.

4.21 mm2
4 mm2
4.25 mm2
5 mm2

Question 1.2

The distance between the array junction box and inverter is 50 m. The array ISC current is 10 A and the MPP voltage is 520 V.

Of the following standard cable sizes, choose the smallest cable you can use while keeping below 1% voltage drop.

4 mm2
5 mm2
6 mm2
7 mm2

Question 2

An array has an ISC current of {11} A and a MPP voltage of {560} V. The distance between the array junction box and the inverter is {62} m.

What is the voltage drop (V) in the array cable if you used 2.5 mm2 copper XLPE-90 cable (resistivity = 0.0219 Ω/m/mm2)?

10.95 V
11.95 V
12.95 V
9.95 V

Question 3.1

An array has an ISC current of {11} A and a MPP voltage of {560} V. The distance between the array junction box and the inverter is {62} m.

What is the voltage drop (V) in the array cable if you used 2.5 mm2 copper XLPE-90 cable (resistivity = 0.0219 Ω/m/mm2)?

11.95 V
12.95 V
9.95 V
10.95 V

Question 3.2

An array has an ISC current of {11} A and a MPP voltage of {560} V. The distance between the array junction box and the inverter is {62} m.

What is this voltage drop in percentage of the array MPP voltage?

2%
2.5%
2.13%
3%

Question 3.3

An array has an ISC current of {11} A and a MPP voltage of {560} V. The distance between the array junction box and the inverter is {62} m.

Assuming you have already calculated a 1% voltage drop in the string cables, can you use 2.5mm2 copper cable for the array cable? Note the maximum recommended DC voltage drop according to AS/NZS 5033:2021 is 3%.

Yes
No

Question 4

An array has an ISC current of {20} A and a MPP voltage of {255} V. The copper cable between the array and the inverter is a 6 mm2 copper cable with PVC-75 insulation. The distance between the array and the inverter is {30} m.

Choose one.

Resistivity for different cables at maximum temperature (Ω/m/mm2)

1.54
1.64
1.55
1.7

Question 5

The image shows a module array with different cabling arrangements. Choose the most appropriate options for a rooftop installation to minimise inductive loops.

Choose 2 answers:

Option 1
Option 2
Option 3
Option 4

Question 6

Identify the minimum required current carrying capacity of a string cable if it contains string overcurrent protection.

Select one:

Imp of the array
Equal to or greater than the current rating of the protection device that is installed
At least 32A, no matter what size array
Isc of the array
It is always equal to the maximum series fuse rating of the modules

Question 7.1

The short circuit current of your modules is {9.5}A and they have a maximum series fuse rating of 25A.
Note that the inverter used does not produce any back-feed current.

KI = 1

Using the value of the short circuit current given and a total number of {3} parallel strings, what is the minimum required CCC for string cables?

22.75
21.75
23.75
23

Question 7.2

The short circuit current of your modules is {9.5}A and they have a maximum series fuse rating of 25A.
Note that the inverter used does not produce any back-feed current.

KI = 1

You are installing an array with 4 parallel strings. Do you need string protection?

Yes
No

Question 8

You are installing an array with {4} parallel strings, with {8} modules in each string. The short circuit current of each module is {8.7}A.
Calculate the minimum required CCC of your array cable.

Select one:

34.8A
10.9A
69.6A
43.5A
87.0A

Question 9

If an array has 6 modules in series and the module Voc is {45.5}V, calculate the minimum voltage rating required for the DC cables.

The lowest expected cell temperature at the installation site is -2°C.

Select one:

327.6V
273.0V
341.2V
546.0V
305.8V

Question 10

What is the maximum allowable d.c. voltage drop for systems greater than 120 V?

Select one:

The maximum permissible d.c. voltage drop is 3%
The maximum permissible d.c. voltage drop is 5%, but is still recommended to maintain a below 3% voltage drop
The maximum permissible d.c. voltage drop is 10%, but it is recommended to maintain below 5% voltage drop
There is no limit to maximum permissible d.c. voltage drop, but it is recommended to maintain below 3% voltage drop

Question 11

What standard must above-ground PV DC cables conform to?

Choose one:

PV1-F
IEC 62930
AS/NZS 5033
AS/NZS 4777.3
Any relevant standard
There is no requirement

Question 12

According to Table 4.6 of AS/NZS 5033:2021, what would be the Earth conductor sizing for an array without d.c. overcurrent protection and a non-separated inverter with powered neutral, if the d.c. active conductor is 6mm2 and a.c. active conductor is 35 mm2? (Hint: Refer to Table 5.1 of AS/NZS 3000)

35 mm2
10 mm2
6 mm2
4 mm2

Question 13

What is the minimum conductor cross-sectional area for both PV d.c. cables and earth conductors according to clause 4.4.2.3 and 4.6.5 from AS/NZS 5033:2021?

Choose one:

4mm2
2mm2
6mm2
There is no minimum conductor cross-sectional area requirement
8mm2

Question 14.1

Consider the following diagram. The VOC of each module is {48}V and the ISC of each module is {11.1}A. The maximum series fuse rating for these modules is {20}A.
The lowest expected cell temperature at the installation site is 0°C.