Solar Saturation, AKA Over Voltage - Goliath Solar & Electrical

Solar Saturation, AKA Over Voltage

AKA My Inverter Keeps Tripping Off (102 ) or My inverter is only producing 50% – 80% (State 567)

In this blog I’m going to address a large issue which most solar companies deal with on a regular basis. They call it Over Voltage, I call it Solar Saturation!

I’ll start with a simple Q and A which should answer most of your questions, then give you the lowdown on why it’s to your (and SA’s) advantage in the long run to tolerate the current inconvenience.


Q: What is Solar Saturation? 
A: Some days during the year, typically in Spring and Autumn where there are sunny days with cool weather, it is not uncommon for solar generation to exceed the amount of electricity being used in a given area. The solar panels are working at high efficiency due to the amount of UV and the relatively cool air temperatures. The usage in peoples’ homes is low due to the fact no heating or cooling is needed. Where Solar generation exceeds the usage in a given area then what occurs is called Solar Saturation.

Q: Why does my inverter cut out on days of Solar Saturation?
A: Your inverter raises its own voltage above the supply voltage so it can try to push power back into the grid, at the same time that other inverters in your area are doing the same thing. As each inverter tries to put power back into a grid that doesn’t require the power, the inverters compete against each other raising the voltage in the grid until the inverter reaches it upper limit of 258 volts and then cuts out.


Q: Why does the voltage increase with the Solar Saturation?
A: This is an electrical equation that is as old as the light bulb, the technical equation is P=IV but the easier way to understand it is: 

The lower the current, the higher the voltage and vice versa. So when more appliances are switched on the current becomes higher, which lowers the voltage.

Q: Why does my inverter cut out at 258 volts or ramp down as the voltage in the area increases?
A: Newer inverters ramp down (reduce the amount of power going back into the grid) before they reach 258 volts and then cut out at 258 volts, older inverters should be set to cut out at 258 volts. Inverters are designed to cut out to protect the network and customers’ homes from excessive voltages which could damage electrical equipment and appliances. If an area has all new style inverters then they should all ramp down rather than reaching 258 volts. 


Q: Why does my inverter appear to be cutting out at voltages lower than 258 volts?
A: Have your inverter settings checked and confirmed in writing by your solar company to make sure they comply with South Australia requirements. There are specific settings for South Australia. If your settings are set to that of another State or Country your inverter may be cutting out much sooner than it should be. We do set up the correct settings form the get go to ensure you get the most you can from your solar system within the rules.


Q: Why am I seeing voltages above 258 volts, which is above the Australian Standard?
A: In South Australia the upper limit of the inverter is allowed to be set at 258volts, which on rare occasions during Solar Saturation, has the ability to raise the grid voltage outside of Australian standards. 


Q: Can SA Power Networks turn down the voltage so my inverter won’t cut out?
A: On days of Solar Saturation the network voltage is a direct result of the inverters trying to put power back into the grid; adjusting the voltage at the supply transformer will have no effect as the voltage in the area is dictated by the inverters competing against each other. All it will do is delay how long it takes for your inverter to shut off. Lowering the transformer voltage may also cause low voltage issues at night in summer and winter when your cooling and heating load is high.


Q: Why did my solar work fine last year but this year it is cutting out often?
A: As more solar systems are installed, the Solar Saturation increases. Solar installation in South Australia continues at an incredible rate and at this stage there is no overall limit to how many homes and businesses can install solar systems.

Q: Due to Solar Saturation did I do the wrong thing installing a solar system?
A: Solar Saturation only happens when more solar is generated in an area than power being used, this mainly happens on days of high UV and cooler weather. Over a 12 month period the percentage of cutting out should be quite low and have minimal effect on your entire year of generation. Installing a solar system is generally cost-effective and also good for the environment.


Q: What are the solutions to Solar Saturation?
A: Your short-term solution is electricity usage which increases as the temperature increases. Air conditioners, fridges and freezers, swimming pool pumps, etc. create a summer load which increases electricity usage and uses all the solar generation your system is producing.

Long term you will be looking at battery storage solutions. As more and more battery systems are installed the grid voltage should stabilise, the batteries will be depleted at night and recharge during the day from solar generation. As battery technology advances and batteries become more affordable, the installation of battery systems will increase. Also as older inverters are phased out, cutting out on over voltage will be less likely.


Q: Why wasn’t I advised about Solar Saturation before my system was installed?
A: The incredible uptake of solar in South Australia has seen changes to the electricity network which has taken a lot of people by surprise. The current electricity network wasn’t designed to work in reverse with power coming back into the grid on days of Solar Saturation. The effects of having so much solar on the network are still being investigated and discussed. Over time and with the correct understanding, hopefully there will be better education regarding the overall effect of solar in South Australia.

Having inverters cutting out on days of Solar Saturation is not a fault, rather it is normal operation of the solar generating system. 


Real-World Graph Examples of Solar Saturation

The above charts highlight a real-world example of solar saturation. Whilst this does show an impact to the total kWh generated (34 kWh vs 39 kWh) this is equivalent to only a few dollars loss in export to the grid. So you are still generating a huge amount of solar energy!

Solar Saturation (MULTI SHUT DOWN) 34 kWh

Non Solar Saturation (NORMAL) 39 kWh

Solar Saturation (ONE OFF SHUTDOWN) 37 kWH

Over Voltage – Trip Chart


The Long & The Short Of It 

Hopefully this helps explain Solar Saturation. I know it’s frustrating for this short period of the year, but please bear in mind that this will get sorted out and generally isn’t a problem in summer as people are using air conditioners, pool pumps etc. 

I’ve heard of people saying run a larger cable to the inverter, but all this is doing is delaying the inverter cutting off by a few minutes. Just ensure that the cable Volt Drop is under 1%.

I know most solar companies are suggesting calling SA Power Networks and getting them to tap down the transformers, but this will only delay the inverter cutting off, and it’s also probably going to annoy them and cause a knee jerk reaction from SAPN that won’t be to your benefit in the long run.

We are very lucky to be able to have export limiting and be able to feed in 5,000W per phase here in SA. This allows us to install lager size solar system to get our houses ready for batteries in a few years time when they become more affordable. I’d hate to see SAPN reduce that to a 3,000W per phase feed in or worse. In Western Australia there is no exporting limiting, meaning the largest size solar system you can put on a single phase supply is 6.6kW with a 5kW inverter…… and that will not be a big enough system to fill your battery when you get one.

So in closing, I know it’s frustrating but please grin and bear it for this small percentage of the year, it will sort itself out. In a few years time when you have a 20kW battery and an electric car charger you’ll be glad that you filled your roof with solar, and Solar Saturation will be a thing of the past!!

To learn details specific to your property, please contact us.

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