Revelations from RenewEconomy on Monday that Malcolm Turnbull had installed solar and battery storage on his waterfront Point Piper home in Sydney generated a huge amount of interest.
But some questions remained: Why does he have it? And is this array – of 14kW of rooftop solar and 14kWh of battery storage (LG Chem lithium ion) enough to take the average home off grid?
We don’t know the answer to the why’s and wherefore’s, because his office is staying Mum on the issue, although apparently the PM delights in showing his monitoring software of the solar output and battery storage operations in his Canberra office. At least he hasn’t totally lost his interest in new technology.
As for going off-grid: well, in the case of Turnbull’s house, that array almost certainly is not even close to being big enough to take his Point Piper mansion off grid. The 14kW solar array would probably generate an average of 50-56kWh of electricity a day, with around 90kWh on sunny days, depending on the set-up.
But we’re going to take a guess and assume that his harbourside mansion consumes more than the average home of 16-20kWh a day. It’s probably treble that amount if you think of all the electronic gadgetry, pool pumps, security gate etc that there could be.
That also means that Turnbull doesn’t have anyway near enough to go off grid. To do that he would likely need 100kWh. And what he has is a relatively small sized battery array for the amount of panels, experts say. But, depending on the set-up of his LG Chem battery storage system, and the inverters in use, it could give him power if the grid went down.
What about for the average home? Would this array be enough to go off-grid?
Experts say that it’s more than enough solar, but possibly not quite enough battery storage. One or two suggest an average home in a sunny area could get by, although three or four days or rainy weather would put it to the test, even with a solar array still producing at around 20 per cent of capacity in those conditions.
Matthew Wright, the head of Pure Electric Solutions, says the combination would not be far off what would be required for Sydney. Winter could be a challenge, but a low consumption, super efficient home could get by.
“If you had either gas for heating (average home) or super efficient air conditioner heat pumps such as the Daikin US7 with a tight building envelope it would do the trick.”
Steve Madson, from Country Solar in Queensland, also says that without bad weather, that array would be sufficient for many homes with low consumption. “I have 10kwh (battery storage) in Townsville and that gets through with air conditioning,” he says.
Shaun Beck, the manager of Solar City, in the Hunter Valley, says Turnbull’s array would be enough to keep some homes off the grid, even if it is heavy on solar and a bit light on storage.
“For an off grid system 14kw is a bit of over kill and the storage a bit low, but it all depends how much power they would need daily,” Beck says.
As for Turnbull’s array, the solar system would likely produce as little as 10-14kwh, or even less if really bad. “So 14kwh storage won’t mean a lot (for going off-grid). I’m sure that won’t worry the uber rich.”
Others are more conservative. For them, the general rule is for storage to be three times the average consumption, to keep the lights on in bad weather. Or use a generator.
But as one said, by having a very big solar array and relatively small battery storage, Turnbull is probably exporting a fair amount back to the grid on sunny days (assuming that the household is not a complete power guzzler).
In that respect, he is probably doing his bit to keep a lid on wholesale electricity prices. “It’s probably the best thing he has done for electricity costs since he became prime minister,” the storage expert said.