“Zero electricity bills:” Ausgrid and Reposit trial compelling solar and battery offer

Households in New South Wales will have the opportunity to effectively quit the grid – or at least the electricity bill-paying part of it – for a period of at least five years, as part of a smart solar and battery storage demonstration project Ausgrid is running in partnership with Reposit Power.

Project Edith – named for electrical engineering pioneer Edith Clarke – aims to show how residential solar can continue to thrive on the electricity grid without being constrained by distribution network congestion.

The project will demonstrate a method of effectively managing a two-sided market, where services are bought from distributed resources such as rooftop solar and electric vehicles to deliver cheaper and more reliable energy for all.

To do this, the first step will be to expand on the virtual power plant (VPP) the two companies have already established on the Ausgrid network, from its current size of 400 households with solar and battery storage to a target of 1,000 participants.

To encourage new comers, Reposit will offer a guaranteed “no electricity bill product,” for an initial period of five years (potentially 10), in return for the customer stumping up $18,000 for a combination of solar (at least 6.6kW), battery storage (at least 11.8kWh) and a “Reposit box.”

Once that system is installed, the household is effectively “abstracted from the electricity system,” explains Reposit CEO Dean Spaccavento, in that it uses the power it needs, when it needs it, without giving a thought to cost or management – that responsibility is handed over to the boffins at Reposit and Ausgrid.

“The grand bargain is you buy solar and battery, you put our controller on it and you give us total control,” says Spaccavento.

“In return for that, we give you zero electricity bills, guaranteed, which means Reposit is taking the risk associated with the quality of the equipment, the quality of the installation, the quality of the trading behavior… [And] if we get it wrong, we wear it.”

But Spaccavento stresses that Project Edith is – crucially – a collaboration, in that it depends a great deal on Ausgrid fulfilling its part of the bargain.

“What’s happening here is that Ausgrid are going to be giving Reposit a safe operating band, through which we can export and import from the network, for a given resident.

“And [Ausgrid] is going to publish one of those for each resident that has a Reposit system on there, and they’ll also publish a price to say, well, this is what’s safe, and this is what it costs to use this much… this much… this much.”

The Reposit controller, meanwhile, makes decisions on when to import electricity from the grid, when to use or store rooftop generated solar power, or when to export solar power, while also making bids into the frequency control ancillary services market (FCAS) and keeping the battery ready for a blackout.

“So Reposit provides the control, and the decision making at that [residential] end, but that decision making is heavily influenced – in fact, almost dictated – by what Ausgrid says it’s safe to do and what Augrid signals is efficient to do,” Spaccavento said.

For Ausgrid, the project is a neat demonstration of the need for the controversial rule change – dismissed by detractors as a “solar tax” and recently given the all-clear by the Australian Energy Market Commission – that will give networks the ability to set prices for the export of solar electricity.

“So this [project] is absolutely dependent on pricing for all services,” said Ausgrid chief customer officer Rob Amphlett Lewis, in an interview with One Step Off The Grid.

“We’re sending a price signal of when it is really valuable for a customer to export their solar and when it’s of negative value for them to export.

“And while [solar owners] might struggle with pricing signals… when the signals get sent between boffins to operate assets, you get a really good outcome.

“What we’re trying to achieve by this this… change in tariffs is to get all this distributed energy to work together, so that it’s not just benefiting the household, but it’s actually working in almost an organic way to deliver a system that delivers for everyone,” he said.

“So that means, when you’re exporting, if it’s a really bad time to export you should be charged for that. If, when you export, it’s good time to export, you should be paid a lot for that. When you’re using your electric vehicle at a time when everyone’s using the system, it should be expensive. When no one is [using it] it should be cheap.

“Then you have electrons meeting demand and demand meeting electrons, not the one way supply meets demand. … Without those price signals, you just get very, very expensive electricity system.”

But what about those solar households that can’t afford to add a battery or, for that matter, an electric vehicle to the mix?

“Two things,” says Amphlett Lewis: “By making the system cheaper, you’re benefiting everyone, so it doesn’t matter whether you’re solar or not, this is effectively going to reduce the cost of decarbonisation and allow us to do things smarter so everyone benefits.

“Secondly, you know, this isn’t the only solution. There’s other solutions as well… We’re looking at community batteries, other people have other ideas about how to how to help customers with just solar.

“The answers to the complex problem of decarbonisation are myriad. This is one of them, and we’re really confident this is going to have a really big role to play, but it’s not going to be the only answer.”

Spaccavento agrees. “I think that getting the right incentives conveyed and accepted and acted upon by consumers with distributed energy resources is the only way that we end up with an efficient electricity system.

“At the moment, those incentives are mixed, and some of them are blocked; the consumer doesn’t see them,” he told One Step.

“Being able to demonstrate to the national electricity market that using technology that mainly already exists, dynamic operating envelope technology from ANU, existing Reposit technology, smart grid software and grid management software at Ausgrid, we’re able to stitch these things together in a way that allows incentives to have the intended effect on the electricity grid.

“And consumers at the same time can just get lower cost, simpler, more sustainable energy which is really what they want.”