Michael Mobbs has been involved in sustainability for more than two decades, leading public discourse with his “sustainable house” blog, cutting his connections to mains water and sewer more than two decades ago, and finally cutting the electricity wires to his inner-Sydney terrace home in March, 2015.
His exploits and determination to lead a self-suficent lifestyle earned him the sobriquet of the “off-grid-guy”. But two years after cutting the link to the electricity grid, Mobbs is deeply frustrated – his off-grid system is not working anywhere near as well as he expected.
For the last few weeks, in cloudy, rainy Sydney, Mobbs has had to turn off the fridge during the day to ensure that the house, which he shares with two others, has enough power for a “civilised life” at night-time. Worse than that, his system has a bug in it that causes it to trip every two days. Flashing digital lights have become part of his life.
“I’m running short of power,” Mobbs complains. He reckons that the system that he has in place is delivering 1kWh a day less than he expected. “I thought this would be a walk in the park, but I appear to have tripped over.”
Mobbs in now looking to replace the system, and has even launched a public ‘invitation” for people to suggest solutions. (Submissions are due on April 13).
But he wants this to be a public discourse, because from his experience he sees a cautionary tale for anyone looking to install battery storage, and particularly those who are looking to go off grid.
“I don’t live off-grid just for myself,” he writes on his blog. “I live off-grid to trial and to show options, create and publish real-life data for others, to give hope through action and accountability. ”
But he admits that his particular journey for going off-grid for electricity is incomplete. “When complete, and the new replacement system is installed soon, the project will show what is feasible.”
Although battery storage has been used for decades, mostly in remote areas that don’t easily connect to the grid, the mass-market is new, and so are many of the products now available to those in the inner city, suburbs, and regional towns.
And battery storage is a complex business – it relies so much on the consumer’s usage pattern, available solar power, local weather, orientation and how it is configured and paired with other hardware and software such as inverters and solar panels. Going off grid requires a bespoke solution.
Some people have the money and can throw surplus dollars and capacity at the solution. Hobbs clearly wants to find a smarter way – and in the inner city, he is restricted by space.
Mobbs says that from his experience it is pretty clear that there is a consumer blind spot. He now emphasises the need to be clear about what is wanted from the system, and for good monitoring and analytics to indicate what is going wrong and when.
So what did go wrong with his system?
In 1996, Mobbs had solar panels installed, a 2.2kW system. In 2015, with a view to going off grid he upgraded his solar system to 3.5kW of solar panels, and installed 15kWh Alpha-ESS battery storage system with a 5kW Goodwe inverter. In all, it cost him $27,000.
At first glance, that looks about right. But it’s the detail that counts. Battery storage experts told One Step that Alpha and Goodwe are both good technologies, but they are best suited for “hybrid systems” which provides storage of excess solar capacity and back-up in case of a blackout. They are not the best option to be off-grid.
Mobbs also admits to not fully understanding the way that off-grid systems work. This graph (below) is an illustration. It shows the promised solar power (orange line), the actual panel output (green line).
It’s a huge difference, but it simply reflects the fact that when a battery unit is filled, any excess solar capacity is “spilled”, because there is no grid to send it back to. So the solar output needs to be carefully configured with usage and battery storage capacity. Some spillage is inevitable – unless you want to overspend on storage – because that is the nature of the beast.
“Remember: it’s the amount of power to be generated that is being installed and bought – not merely the things on the site,” Mobbs notes on his blog. “Merely having solar panels, inverter or batteries does not mean the anticipated amount of power is being generated (or stored).”
Mobbs reckons that with the extra 1kWh of available power he had expected he could “potter along”. He tells One Step: “So now I have not got enough. This month of rain in Sydney has given me over the horizon radar … it’s like Game of Thrones, winter is coming.
So Mobbs is looking to replace this set up and get a new inverter and battery storage. But he wants to make a few points clear about his experience, and the lessons to be drawn from it. The biggest lesson, he says, is the importance of data.
“What I am trying to do is tell the whole world, get good data and work out what you need. I am driven by data, I’m in the game of recommending products, but you have to be careful because you are not buying hardware, you are buying a promised amount of power. And if it doesn’t deliver, you need the data to prove that you haven’t got that promise.”
And data is important even for those who just have solar panels – some studies have shown that more than one third of all solar systems (there are 1.6 million rooftop solar systems in Australia) are working below par, often for some easily fixed fault, but the households simply don’t know.
“It’s not enough to say that we have got a lot of solar households in Australia. We have got to be able to say that they are delivering on their promise,” Mobbs says.
Other issues he has come across is the lack of a formal second hand market in solar panels. When he took down his original array, the installer didn’t know what to do with them. But soon enough, Mobbs found someone in the Blue Mountains who hopped in his ute to drive down and pick them up. He also wonders why there is not more recycled metals used in such systems.
Marlon Kobacker, of Sustainable Future Group, which has reviewed Mobbs’ problems, believes there must have been some communication break-down when the equipment was ordered. He says Mobbs has sized the system for around two or three days, when most people might size it for a week. And he doesn’t want a fossil fuel back up generator.
“In running the EOI process we doing now for either repairing or replacing system we are taking approach that we need be very clear with the brief up front.
“We want to get certainty round how system will perform, on the predicted output, and much better data interface … and to get smarter controls, load controls, and so at least there can be some sort of alarm when the system is heading towards a shut-down.