What AS/NZS 5033:2021 request for ISC is current on the inverter? Which brand of inverters can be used in Australia?

Latest Australia & New Zealand Solar Installation Standard AS5033.2021 has been officially implemented on 19 May 2022. There have been some updates regarding high panel short circuit currents (ISC). These updates are explained below in highlights: 

1.25×PV Panel ISC ＜＝PCE(Inverter) DC input ISC

i.e. 1.25 times the PV string short-circuit should not exceed the maximum DC input short-circuit current of the inverter.

After researching this, I have found out the most popular panel brand like JINKO P Type JKM 415, LONGI LR5-54HPH-415M, YINGLI 415, ISC between 13.71-14.0A, 1.25×PV Panel ISC is between 17.14-17.5A. This means that the DC input ISC on the Inverter is at least more than 17.14A. Considering increasing efficiency and output power of solar panels, DC input ISC on Inverter should be more than 17.5A.

Let us check the different brand inverter datasheets in Australia:

Model: 3-6kw Single Phase Inverters

1. Goodwe： ISC is 13.8A for D-NS 3 to 5kw, ISC is 16.3A for T-DS 3 to 5kw, those inverters fail to use for 390watt or 415watt panels.

2. Growatt： Min 2.5kw to 6kw, ISC is16.9A, these inverters fail to use for 415-watt panels.

3. Sofar： G3 3 to 6kw, ISC is15A， these inverters fail to use for 390watt or 415-watt panels.

4. Each Energy：3-6KW, ISC is 22A, these inverters are suitable to use 390-watt or 415-watt panels.

Model: 5-10kw Three Phase Inverters

1. Sungrow： SG-RT 5 to 10kw, ISC is16A， these inverters fail to use for 390watt or 415-watt panels.

2. Goodwe： GW 5 to 6KW, ISC is15.6A， these inverters fail to use for 390-watt or 415-watt panels.

3. Huawei: Sun 5-10kw, ISC is 15A， these inverters fail to use for 390-watt or 415-watt panels.

4. Growatt: Mod TL3-X 3-9kw, ISC is 16A， these inverters fail to use for 390-watt or 415-watt panels.

5. Each Energy： EET6Kpro-10KW, ISC is 22A, these inverters are suitable to use 390-watt or 415-watt panels.

After this investigation and enquiry into the inverter brands Goodwe, Growatt, Sofar and Huawei – they cannot be used within Australia for solar installations because of the low ISC. All the above-mentioned 4 manufacturers have stated and claimed that they have increased the ISC after testing has been taken out by them. 

I have sent an email to CEC to confirm the statement by the inverter manufacture/s stated above –

CEC has replied with the following statement “It is part of the CEC product listing terms and conditions that device ratings that are recorded on the CEC database match the values shown on the Certificate and Test Report. If the manufacturer wishes to change the inverter nameplate ratings then the inverter will need to be re-certified and an application submitted to the CEC to update the CEC listing.”

After this information from the CEC, I can confirm that the statement from the manufacturer cannot be accepted, the inverter manufacturer will have to do a new test report through a Lab like TUV if they want to increase ISC.

If the ISC on the inverter is less than the solar panel ISC *1.25, this means the solar system design and installation is not compliant with the standard of AS/NZS 5033:2021. A defect notice will be issued after inspection.

Another factor which is called Max DC input current (Imp) on the inverter will also affect the whole efficiency of the solar system.

As far as we know, the DC current from the solar panels to the inverter can change depending on irradiance. When the sun power becomes stronger, the DC current becomes stronger also and the solar power generation by the solar system also becomes stronger. 

For example, the Jinko 415-watt P type panel – DC current from the panels is 13.48A by the condition of sun power is 1000-watt per square meter. The DC current will be more than 13.48A when the sun power is more than 1000-watt per square meter. 

More than 80% of the area in Australia has sun power of 2000 watts per square meter, this means the Max DC input current on the inverter must be more than 13.48A.

After reviewing other brands of panels Imp, we have found out the Imp is between 13.4 to 13.5A with the panel models from 390 to 600-watt. This means that 13.5A is the Min Imp on an inverter.

The daily DC current graph from panels input to the inverter is as below. I have researched the datasheet of all inverter brands and found out SMA, Sungrow, Goodwe, Growatt and Huawei inverters have not designed the suitable Max DC input current (Imp) because those brand inverters’ Imp is less than 13.5A.

The shadow area below will outline the solar power waste in the period between 11 am to 2 pm if the SMA, Sungrow, Goodwe, Growatt and Huawei inverters are in use/installed at your home.

3-6 Single phase Max input current (Imp) comparison

Model: 5kw Single Phase

1. Sungrow: Imp 12.5A, fail

2. Goodwe: Imp 11A, fail

3. Huawei: Imp 12.5A, fail

4. Fronius:  Imp 12.0A, fail

5. Each Energy: Imp 18A, good

Model: Three Phase 5-10kw

1. Sungrow: Imp 12.5A, fail

2. Goodwe: Imp 12.5A, fail

3. Huawei: Imp 11A, fail

4. SMA: Imp 12A, fail

5. Growatt: Imp 13A, fail

6. Each Energy: Imp 18A, good

Graph as below:

For the Single-phase inverters between 3 to 6kw:

Goodwe, Growatt, Sofar and Solis 4G/5G models fail to match solar panels (more than 390-watt) under AS/NZS 5033:2021 because of low ISC.

Fronius, Sungrow, Huawei, Goodwe and Sofar fail to perform at best efficiency due to low Imp.

SMA and Each Energy are good on both ISC and Imp.

For the Three-phase inverters between 5 to 10kw:

Sungrow, Goodwe, Growatt, Huawei and Sofar fail to match solar panels (more than 390-watt) under AS/NZS 5033:2021 because of low ISC.

SMA, Sungrow, Goodwe, Growatt, Huawei and Sofar fail to perform at best efficiency because of low Imp.

Fronius and Each Energy are good on both ISC and Imp.

We suggest the inverter manufacturer to update the material to increase both ISC and Imp to match the increasing panel output power.