Many Australians are keen to cut ties with electricity companies by installing solar panels and batteries with view to taking their homes entirely off the grid. And who could blame them?
The idea of energy independence is very attractive, but there are some very good reasons for keeping a mains grid connection.
This segment is from SolarQuotes TV Episode 9, which is all about off-grid living in Australia.
— Transcript begins
Finn: Now, here’s a question we get asked all the time.
“I’m fed up with paying a daily charge to access the grid. How do I tell my retailer to get stuffed and take my suburban house totally off the grid?”
Well, it’s certainly possible to go off grid in the city, and it has been done with varying degrees of success in recent years.
The example I’m going to take is in the Perth suburbs. It was built by a bloke called Martin Chape and he started the project way back in 2011. The system has evolved over the years, and now he’s settled on:
- 10kW of solar
- a 20kWh BYD battery
- a diesel generator
- a Selectronic SP Pro inverter to control the battery and genset1.
- and a Selectronic-compatible Fronius Primo solar inverter
If you’d like a similar set-up on your home, professionally designed and installed, don’t expect much change from $50,000 – and you’ll still need to pay for diesel.
Forget Off-Grid In The Suburbs – Go Hybrid
So, now Martin has a system working nicely after many years of experimenting, what is his advice to others who want to go off-grid in the city?
Simple: Don’t – go hybrid instead.
Hybrid is simply solar, batteries and the grid connection. Martin has realised that if you have a grid connection available, you should absolutely use it as a cheap, silent backup generation source. It means you don’t need a dirty gen set, and you can get away with less expensive battery storage. And, there’s no need for a specialist off-grid design and install.
It will save you a fortune.
So, to answer the question that we get all the time:
“Can you go off-grid in the city?”
Yes, absolutely you can. The technology is available. It works brilliantly. But I wouldn’t.
I’d keep that connection to the grid. You’ll still get no bills, but you’ll have that grid connection and you can share your solar with your neighbours2.
— Transcript ends
For more examples of Australians living comfortably off-grid, view SolarQuotes TV Episode 9. For other SQTV episodes and great videos on solar power and battery storage, visit our Youtube channel – and don’t forget to subscribe!
By the way, if you’re still keen an off-grid system for your suburban (or rural) home, it’s incredibly important to choose an installer with the right skills and experience. SQ can arrange for quotes from trusted solar professionals.
Footnotes
- View a video segment on Selectronic battery inverters here, taken from SQTV Episode 9. ↩
- Finn is referring to surplus solar energy being exported to the mains grid where it can be utilised by others and offset fossil fuel based electricity generation. ↩
About Michael Bloch
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We installed a fully off grid set up and brought on line in July 2018 to a property close to the Murray River. In this case, it was outrageously expensive to get the power from the grid to the house.
The system consists of 10kW of Tindo solar panels, 31kW hrs of LYP Winston cell battery storage and 10kW continuous inverter capacity. It does have a petrol generator but it has never cycled on in anger since the system was commissioned.
It did not cost $50,000, so maybe the product prices need to be examined or the actual cost of design and installation needs to be looked at with a view to sharpening the pencil.
These people are heavy power users, over the holiday period, 5 families live in this house, so it’s not like they baby the system. These are city people who don’t have a clue about energy conservation or desire to limit the power they use.
T1 Terry
I’m sort of wondering how EV cars will change the landscape for home Solar design. The off grid system you discuss works well for the current world but what about upsizing the panel count and battery capacity and control to optimise for EV use. If your working during the day you need an overnight charge possibly from a larger battery to include your daily mileage. The other possibility is using the car capacity in case of emergency with power outages and removing the generator requirement. Smarter chargers to allow for the backup capability to be turned on and off would be cool.
So the question is what’s currently available in this area and what do you see on the near horizon?
There area already EV’s on the market that can move energy in and out of the EV on board battery. Considering these new EV’s have between 32 kWh and 40 kWh, that is a lot of energy storage available. Changing mum’s taxi to an EV will have the EV charging from the rooftop solar during the day …. and with the many charging points springing up at workplaces to get them green points, the work EV could actually be bringing electrical energy home ready for the peak demand period ….. The work EV only needs enough battery storage to get back to work the next day, so that provides a lot of energy storage.
There is quite a big move to recycling used EV battery that have passed their use-by date as an EV battery, but still work fine for the slower charging and discharging rates a house battery requires. This means the old battery out of the EV could store a full recharge for the work EV during the day, then take all night to recharge the work EV …..
The problem with hoping to recover the grid connect cost from reselling to the grid, really depends on the concentration of solar in that area, More solar than the area network can cope with, the higher the mains voltage climbs until the solar inverter turns off, then there is no revenue offset generated ……. only requires the question to be asked on the many forums and social media sites about people not getting the amount of revenue from the feed in tariff that the seller/installer suggested you would get …..
There are plans in South Australia being promised, where very cheap power can be bought from the grid during peak solar periods, this could be used to recharge the batteries for the house and the EV … even the used set to charge during the day so the work EV can be recharged over night without buying the energy at a higher price from the grid. This all requires a meter change and a plan change …. a two edged sword, the peak power prices come into effect during the peak periods, and the grid wants access to that power you stored in the batteries you paid for and have to maintain ….. and you still have to pay grid connection charges ……
If the networks want to stop people going off grid, drop the grid connection fees completely, then there would no longer be a huge advantage in going off the grid ……
T1 Terry
I’ve got 6.6 kWh solar system and want to install a 12 kWh battery for use during 4pm-9pm peak demand time when it is most expensive. Also for blackout protection. I’m told that during blackout I can only have one light circuit and one power point circuit working in the house. So basically I can have the equivalent of a couple of iPhone torch lights and a camp stove during blackout. Yet during 4-9 pm I can run the whole house of the battery when not in blackout!!?? Can someone please explain this huge discrepancy in plain English.
The best explanation the potential installation guy has so far is that if I run the whole house during blackout I will flatten the battery off n 8-12 hours. My response is if I am dumb enough to run everything and flatten the battery then it’s my problem. Am I missing some simple explanations that haven’t been explained to me?? Thanks in advance.
Hi Peter,
Sounds like you have a reasonable grasp in terms of kilowatthour battery capacity. I have a link here that touches on it and some text from an upcoming blog that will I trust help explain kilowattspeak. Please let us know if that clarifies it for you.
https://support.solarquotes.com.au/hc/en-us/articles/6617174897551-Can-I-use-my-generator-to-fool-the-grid-connected-solar-into-working-during-a-blackout-
Raw Grunt; It’s The Other Capacity
If you have a particular load that needs to be backed up, such as a pump to deliver tank water to your taps or a firefighting pump then this needs to be documented for the installer. Electric motors are well known as being difficult to start, the instantaneous demand they place on the supply can be as much six or eight times the running current.
So your 400watt rainwater pump needs 2.4 or 3.2kilowatts to kick it in, over and above whatever you might be using normally.
This is referred to as surge current and many inverters will have a specification for 5kW nominal throughput and a separate number for peak capacity with a time limit of perhaps 10 seconds.
Often this means a modern lightweight hybrid inverter will surge to 120% ie 5kW continuous output and 6kW peak output for 10 seconds. For average houses with modest loads these systems will cope well enough. However the fine print is still important.
Eg Qcells Hybrid units have 6.51 / 13.03 / 19.55 increments in storage capacity but if you don’t have at least 13kWh of battery, the surge capacity is also lower because the inverter relies on having a decent amount of battery capacity to draw on.
However the best inverters have better ratings, so if you want heavy duty capacity, a proper grid forming 5kW machine will surge to 12kW. That’s 240% for 30 seconds, and with proper thermal management they specify more increments, 8.7kW for a minute, 7kW for 30 minutes and so on.
This capacity is expensive but it is available for critical applications… like a 3kW fire pump.
Thanks for the reply. Yes I understand surge requirements. Are you saying that from 4-9pm when I am running off my battery, it can handle surge requirements but during a blackout when I’m running off my battery it can’t handle surge requirements??? I’m not being difficult, just wanting a reasonable explanation. Maybe installer is lying to me and I won’t actually run on the battery from 4-9pm. Maybe it will be half battery and half grid?? Who knows eh.