As rooftop solar continues to boom around Australia, an increasing number of households are coming up against strict limits to the amount of energy they are allowed to export to the grid, with many finding that they cannot export their solar at all.
The practice, called solar export limiting, is not a new one. Australian network service providers have been progressively introducing solar export limits for years on their grids, and say it is needed as a way of heading off voltage stability problems in areas of high rooftop PV penetration.
A rooftop solar system’s grid export limit is determined by the local electricity network operator – sometimes on a case-by-case basis, sometimes according to an across-the-board standard, and typically at around 5kW.
But as more and more solar is installed on ageing grids designed and built to carry electricity one way only, networks are tightening their limits on solar exports and consumers are rapidly losing one of the key incentives for investing in the first place – feed-in tariff payments.
According to Andy McCarthy, whose hugely successful Gippsland Solar business was acquired by RACV Solar in late 2019, on certain solar-heavy parts of Victoria’s Powercor grid, as many as one in three installation jobs are being either heavily restricted or limited to zero.
And while for the networks, this is a ready and ratchet-able solution to a problem that has manifested itself far quicker than they had anticipated, for consumers who are relying on a feed-in tariff for a good rate of return on their investment, export limiting is a problem – particularly with new inverter standards looming that could act as another layer of curtailment (but that is another story).
So what can consumers do if their exports are set to zero? Are increasingly low feed-in tariff payments even worth fighting for? And what can networks do at their end to better accommodate rooftop solar and make the most of all this cheap energy being generated on their grids?
For some consumers – particularly those motivated less by economics and more by the thrill of energy independence and ‘sticking it to the man’ – the obvious solution is to add a battery to the mix, to store excess solar generation for use when the sun goes down.
In Victoria, where there is a generous residential battery subsidy on offer, RACV Solar’s McCarthy says he has seen a direct correlation between the increase in solar export limiting and the uptake of home batteries.
“We’ve seen a tripling of the amount of solar installations with batteries over the last six months,” he told One Step Off The Grid in an interview this week.
But for households without access to generous battery discounts, or for Victorian households that have already tapped the Solar Homes Rebate for cheaper rooftop PV, batteries are still largely out of reach. Some battery prices are even going up!
Batteries aside, there are other ways to maximise solar self consumption and minimise waste, including installing smaller systems to start with, using smart technology to shift loads to when the sun is shining.
Another option – although this one is a work in progress – is dynamic or flexible exporting. As RenewEconomy has reported, “dynamic” or “flexible” exporting holds promise as the new standard for managing the huge growth in rooftop solar systems across Australia, and is being currently tested in a trial backed by the Australian Renewable Energy Agency.
The ARENA-funded trial, which is being conducted in South Australia and Victoria, will look at how smart controls and communications can allow network companies to “manage” the export of rooftop solar back in to the grid, subject to local conditions and what is happening elsewhere in the grid.
The idea, which has also been tested in Queensland and in being considered in Western Australia, is that it will free up all households to export solar power – so no zero limits – but the amount they are allowed to export will vary from time to time, according to the needs of the grid.
“The next stage is one that brings the network operators along for the ride and uses technology to make renewable energy dispatchable, which is still far cheaper than adding infrastructure,” McCarthy said. “It’s about empowering consumers, and decentralising the market.”
In the meantime, he adds, it is vital that solar retailers and installers are honest and up front with customers about export limits and what they mean in terms of their return on investment, if they can’t access feed-in tariffs.
“That’s the way we present it to our clients: ‘This is the system we’ll provide if you can’t export to the grid’.
“We need to stop talking about feed-in tariffs being the panacea for solar,” he said. “The glory days of feed-in tariffs are gone.”
In South Australia, where a world-leading uptake of rooftop solar has required a more structured approach to regulation, all households are now limited to 5kW of solar export per phase, making the situation much clearer for installers and consumers.
(South Australia has also become the first state in Australia to introduce strict new inverter standards that allow for rooftop solar systems to be switched off remotely at the request of the Australian Energy Market Operator.)
But difficulties are starting to arise in the commercial sector in that state. According to Mark Yates, the founder and managing director of vertically integrated solar business Yates Electrical Services, based in Renmark, his team have had some recent jobs where they have applied for 100kW and been given a 40kW export limit.
“What we are seeing now is that the networks are … really sort of tightening the screws.
“They look at voltage rise impacts, they look at voltage step change, they look at fault level contribution and they look at system strength studies… All of these things are looked at by the network on a case-by-case basis because, obviously, the bigger the generator, the greater the impact it has on the network.”
But Yates also notes that SA Power, South Australia’s network operator, has been “quite proactive” in addressing these issues, including through its part in the aforementioned ARENA trial of flexible exports.
“They want to see more and more people connect. But they also need to manage it in a fashion that doesn’t impact the security of the network,” he said.
“Ultimately, networks dictate what customers can and can’t do. It’s really up to the network to allow customers access… and I guess where the networks invest their money will determine what limitations are imposed.
“In my opinion, networks should be investing in upgrading their low voltage infrastructure, especially in South Australia where some of our infrastructure is 30 or 40 years old, even older,” Yates said.
“And I think networks should be considering investment network batteries or network storage, because things like that will allow customers to have better access and availability to the grid for exports.”
For Yates, whose solar broad-ranging solar business has energy retail and generation licences as well, communication between all arms of the electricity sector is also key.
“It’s such a disjointed business, no one seems to communicate with anyone and everyone seems to be doing their own thing.
“So I think there needs to be better alignment between all of the participants in the network for this to be able to work effectively… because at the moment it’s definitely not happening.”