What is Grid Over-Voltage and Why Does it Occur?
When powerline voltage connected to the house go over Australian standards, grid over-voltage occurs. The grid voltage Australian standard AS 60038 is 230V +10% -6%, which is a range of 216V to 253V. The Australian standard for your inverter instructs that it must disconnect from the grid if voltage exceeds 255V for 10 minutes or exceeds 260V for any amount of time. If any of these limits have been breached, the inverter trips and an ‘over-voltage’ error displays.
A possible reason this may occur could be that the grid in your area is functioning outside of the above standards. The local grid could also be set slightly below 253V within the standard, but the inverter is adding more power to it and causing the voltage in the grid to rise over the limit and shut off the system. The maximum voltage rise for a system must be 4.6V (2%). For example, the local grid may be functioning at 252V, and your inverter is exporting 4V back into the grid pushing it over the grid standard.
Energy Distributors Running High Voltage to Homes
In 2016, significant changes to AS 4777.2 occurred and a 255V output was set on inverters. Before this change, inverters were able to increase voltage if the grid voltage was too high. After this change, inverters were unable to overcome high grid voltage and just shut off instead. This raises considerable issues as energy distributors were already supplying electricity at voltages close to the high end of the Australian standard, some even slightly above 253V!
Implications of these issues mean that your energy consumption rises, and power bills may increase. This depends on factors such as the type of appliances in the household or modernity/type of the inverter. Rooftop inverters are set up so they operate at a slightly higher voltage than the grid so they can send energy back into the network. If energy providers are setting the grid to operate at already high levels, then the system will continue to have issues with tripping.
How Can These Issues be Overcome?
Your DNSP (electricity provider) has a legal obligation to fix the voltage in your area if it has exceeded the Australian standard. We recommend contacting your DNSP to take this matter further, you can request them to lower the voltage to avoid future grid over-voltage errors occurring. The contact numbers of the DNSP for each state is provided below.
Use this tool to find out who your DNSP is (VIC ONLY): https://www.energy.vic.gov.au/electricity/electricity-distributors
Who Do I Contact?
VIC:
Citipower – 131 280
Jemena – 1300 131 871
Powercor Australia – 132 412
AusNet Services – 131 799
United Energy Distribution – 132 099
Essential Energy – 132 080
NSW:
Endeavour Energy – 131 003
Essential Energy – 132 080
Ausgrid – 13 13 88
QLD:
Energex 136 262
Ergon Energy – 132 296
TAS:
TasNetworks – 132 004
ACT:
Evoenergy – 131 093
Essential Energy – 132 080
WA:
Western Power – 13 10 87
One Response
I have a 5KW PV system with a 5KW Inverter that’s about six years old, that seems to be working OK. I had a health check done on it, by Solargain, following the events mentioned below and no issues were found.
Now, attached to my domestic power, I have a 2kVA Schneider Electric UPS system set up to protect some computer equipment in my home office. For more than a year now I have been getting an increasing number of overvoltage events emailed to me from the UPS management card, during particularly sunny parts of the day only. I have verified the overvoltage events are only triggered when the UPS detects input voltage over 253V. So, they are definitely valid overvoltage events. I often check the logs (2 week retention) and can see extended periods of between 253.4V and some as high as 254.8V. I let this slide until, February, last summer, when my Inverter reported it was going offline, during an overvoltage event. Following that event I booked a health check, as mentioned above, and raised the issue with Jemena. They said they could move my property onto a lower voltage phase, which they did. This seemed to have made the issue go away for only a short while. Now we’re coming back into summer and the events are happening again. So, I followed up with Jemena to let them know the issues was still happening. At this point they provided me with the following, in an email, with a graphic attached, showing two blips, in the last year when my output has apparently exceeded ‘5kva”. As I only have a 5K solar system, how can I produce more than “5kva”? Anyohow, this is what they said…
“As discussed, please see below load profiles you can see two times exceeding 5kva( approximately 20A) and I suspect this could be an inverter setting. If you can please check with your installer the setting of the inverter.”
Not entirely sure what the relevance of two events, reported on the meter over a nine month period, is to the persistent and ongoing overvoltages I have been getting almost every sunny day on my domestic supply?
Are they just throwing me a furphy with this or do I need to get a solar maintainer in again?