Does my solar battery need anti-islanding testing?
Yes, if it is connected to the grid. Evoenergy requires grid-connected inverters on its network to be tested at least once every five years, and its testing procedure covers battery inverters, hybrid inverters and battery-only inverters. Evoenergy sends a reminder when the test is due.
Evoenergy's Solar safety page explains that a battery may be able to supply part or all of a home during a power outage, and that to do this safely it must first disconnect from the Evoenergy network. The anti-islanding test checks that it does.
Tests 1a and 1b apply to every installation. Tests 2a and 2b apply only to battery systems that contain both an inverter main switch and a backup main switch.
The requirement is for grid-connected systems: Evoenergy's technical requirements for small systems exclude systems that are off-grid. What to do when the reminder arrives is explained on our Evoenergy inverter test page.
What are tests 2a and 2b?
They are the two tests Evoenergy's procedure adds for a backup system. They take the same measurements as tests 1a and 1b, at the backup main switch instead of the inverter main switch, and the procedure sets the same limits:
| Test | Switch | Requirement | Applies to |
|---|---|---|---|
| 1a | Inverter main switch | Ceases supply within two seconds | Every installation |
| 1b | Inverter main switch | Holds off for more than 60 seconds | Every installation |
| 2a | Backup main switch | Backup system ceases supply within two seconds | Battery systems with a backup main switch |
| 2b | Backup main switch | Backup system holds off for more than 60 seconds | Battery systems with a backup main switch |
At the backup main switch, the two tests run in order:
- Test 2a. We turn the backup main switch off and time how long the backup system takes to stop attempting to export power, using a voltage probe on the installation side of the switch. Evoenergy's procedure requires the backup system to cease supplying power within two seconds of a loss of mains.
- Test 2b. Mains are restored and we time how long the backup system takes to start exporting again, using a current probe on the installation side of the switch. The procedure requires that it does not resume supplying power until mains have been present for more than 60 seconds.
Tests 1a and 1b work the same way at the inverter main switch, and are explained in what an anti-islanding test is.
What is a backup main switch?
The backup main switch is the AC isolation point immediately upstream of a backup device, such as a Tesla Backup Gateway. The inverter main switch is the AC isolation point immediately upstream of the inverter.
The procedure explains that battery systems sometimes have a backup device that prevents the system from islanding while allowing some circuits to remain energised. Only systems with such a device have a backup main switch, so tests 2a and 2b are done only where there is one. The declaration asks the same question on its first page: whether there is a backup system with a separate main switch at the address.
If you are not sure what your system has, tell us when you book. A photograph of your switchboard and battery equipment helps us confirm it before the visit.
Will my battery backup turn off during the test?
Usually not, but it can during tests 2a and 2b.
Turning off the backup main switch can de-energise backup loads, depending on the battery's charge level and on whether there is a fault in the battery system. Evoenergy's procedure requires us to explain that risk before we start and to proceed only with your consent. In most cases backup circuits stay energised throughout.
So we ask about your backup circuits when you book. If something on them must not lose power, tell us beforehand, so you can plan for it before you give consent.
How is a hybrid or battery-only inverter tested?
With the same tests, set up to suit the arrangement. The tests time how long the inverter takes to stop exporting, and Evoenergy's procedure sets out how each arrangement is connected for them:
- Battery-only inverters, including hybrids with no panels connected. The DC supply from the battery stays connected to the inverter for all the tests.
- Hybrid inverters with panels connected. The DC supply from the solar array stays connected, and the test must run while the system is producing more than 20 per cent of the rated output of the PV array or the inverter, whichever is less. To measure an export, the DC battery supply may need to be disconnected, following appropriate shutdown procedures.
- A battery inverter alongside separate solar inverters. The other PV inverters may need to be switched off during the tests so an export can be measured.
We work out which of these applies from what you tell us when you book, and check it on site before the first switch goes off.
What extra paperwork does a battery system need?
One extra page, and only when tests 2a and 2b are done. Evoenergy's Inverter anti-islanding test declaration has three pages:
- Page 1 covers the installation, including whether there is a backup system with a separate main switch.
- Page 2 is completed for each inverter, though micro inverters that share a main switch can share one. It records the inverter, the capacity of any batteries connected to it, and tests 1a and 1b.
- Page 3, the Inverter backup system anti-islanding test declaration, records the backup device, the number of inverters connected downstream of it, their total kVA, and tests 2a and 2b.
We complete the declaration, keep the original, give the owner a copy and email a copy to Evoenergy, pass or fail. Evoenergy encourages you to keep your copy while the inverter remains in service and connected to the network.
What should I tell you before booking?
Choose your system type in the booking form, and tell us:
- how many inverters there are, including any separate solar inverters, and the make and model of each
- the make and model of your battery, and whether it can supply part or all of your home during a power outage
- anything on your backup circuits that must not lose power
- your suburb, and a photograph of your Evoenergy notice if you have one
Use the booking form, call 0400 331 705, or see the contact page. We quote before we test, and what changes the price for a battery system is set out under inverter testing cost.
What else do people ask about battery testing?
Is the anti-islanding test the same as a solar system health check?
No. For a battery system, Evoenergy's test consists of the timing tests at the inverter main switch and, where there is one, the backup main switch, recorded on the declaration. A health check or panel inspection is a separate service and not part of Evoenergy's requirement.
I have more than one inverter. Does each one need testing?
Yes. Evoenergy's procedure requires a separate form for each inverter, except micro inverters of 1 kVA or less on the same inverter main switch, which can share one. Where a battery inverter sits alongside solar inverters, the other PV inverters may need to be switched off during its tests so an export can be measured.
Why does the weather affect my booking?
If panels are connected to the inverter, Evoenergy's procedure only allows a valid test while the system is producing more than 20 per cent of the rated output of the PV array or the inverter, whichever is less. If it is not, the test has to wait until it is, so we book around the forecast.
Can I test my inverter myself?
No. Evoenergy's procedure warns that the tests involve working with live DC and AC voltages, and that they must only be carried out by an ACT licensed electrician.