Home-owners have flocked to solar, with more than two million PV systems installed on rooftops across the country. But the many hundreds of thousands of blocks of flats around Australia are largely naked of purple panels. When a roof has more than one owner, selling solar becomes a harder prospect. Things are made more difficult when property owners struggle with the idea of paying for a PV system where lower power bills will benefit someone else – their tenant.

Melbourne-based company Allume Energy is circling this residential PV quandary with its SolShare technology, what it says is the world’s first behind-the-meter solar distribution system – or power division control system, to use the technical term.

“We take the power from a single PV system and that goes into the SolShare, which is wired in behind-the-meter to multiple separately-metered units,” says Allume Energy head of business development and technical sales Jack Taylor. “We connect it between the meter and the person’s apartment, on the main switchboard of the apartment building.”

The technology is being used in about 40 multi-tenanted blocks where all the owners have agreed to share the cost of a solar system.

Share the sun

Sounds good so far, but if the owners have shared the cost of rooftop solar equally what’s the guarantee that they will each get to use their fair share of its output? That comes down to the delivery model they have signed up for, says Taylor, first describing a scenario where the body corporate buys the PV system and monitors the residents’ demands.

“Depending on who’s using what amount of energy at any time, we’ll direct solar to where it’s needed to maximise the consumption of solar electricity,” he says. “We change delivery of the solar every 200 milliseconds.”

The automated system is sensitive to any electrical transaction, such as a kettle being flicked on or kids fiddling with the air-conditioning settings, but it also will pick up changes in behaviour, such as a long dip in load at an address where the occupant is on holiday.

“SolShare won’t send them very much solar energy because it will identify they’ve only got, maybe, a fridge load, so it will occasionally send them a little bit of solar for that. The rest will be sent to the other apartments.”

The system is also smart enough to avoid freeloaders, he says, where a resident who may be at home all day running the air-con on full while everyone’s at work will not benefit at everyone else’s expense.

“The SolShare logs how much solar has been delivered to each of the apartments and over the course of a month will ramp up or ramp down the solar delivery if an apartment has received less or more than another,” he says. “That works especially well for people who have been on holiday. When they return they end up catching up with their neighbours.”

Someone who is away longer than a month will see their allocation of solar exported to the grid in return for the feed-in tariff.

Salvation solar

In July Allume was awarded $220,000 in ARENA funding to trial a different style of delivery model, where a single buyer on-sells solar to other occupants in its commercial property.

Under the pilot program, financier Green Peak Energy will sell the output from 487kW of solar installed on 10 multi-unit commercial properties owned or tenanted by The Salvation Army and other non-government organisations.

Any energy not used by The Salvation Army will be on-sold to other tenants of the properties, where The Salvation Army becomes the retailer under its power purchase agreement with Green Peak Energy. So, the Salvos buy cheap energy from Green Peak and sell what they don’t need for a small profit to their tenants, who will still get a better deal than the retail rate.

“It’s nice for us to create an environment where the Salvation Army is saving money and reducing their carbon footprint and also able to make a little bit of money by selling any additional energy to their tenants,” Taylor says.

The first site to be installed will be on The Salvation Army’s Glenorchy City Corps in Glenorchy, Tasmania. If the $1.04 million pilot project is successful, Allume Energy intends to roll out the project across the not-for-profit sector.

SolShare’s job, he says, is to take PV generation and divide it among consumers, whether that be in a residential building, a commercial building, a mixed commercial and residential property – it doesn’t matter. “Whether it’s three-phase, single-phase – we don’t mind. We just connect it to whatever’s there and then the client gets to choose what delivery model they would like.”

Taylor admits corralling owners of units in a block of flats into an investment decision about clean energy is not straight-forward. “We get a large number of inbound leads from people who live in apartment buildings and we provide them with proposals,” he says. “To improve the likeliness of having a system installed, it’s key to speak to the other owners about a SolShare solution and get a good amount of buy-in from the start.”

The company is about to complete an install in Victoria where 11 of the 63 apartment owners are buying into the system along with it being connected to the common light and power, he says. In NSW, a project in Sydney has seen eight owners among a block of 32 apartments sign up for a system that will see half the energy sent to common light and power. In that example, the body corporate will pay for half the system.

Rooftop retailer

Another model available to owners is where they all agree to be supplied by an energy retailer that will install a PV system that includes SolShare. Residents who opt in will then benefit from reduced electricity bills. So far Allume has delivered such projects with retailer Locality Planning Energy, or LPE, in Queensland and it is working on a pilot with Origin in Victoria. “They get their grid energy and solar from the same retailer,” he says. “That’s where we are really finding traction in the apartment market. It has the nuance of an embedded network but it doesn’t have any of the negatives.”

Exiting the deal for another retailer is simple, he says, but it means disconnection from the solar system.

Allume is making inroads in South Australia, Taylor says, and is selling units steadily to LPE in Queensland. “That’s going to be our biggest region,” he says.

Community housing is another obvious sector where the technology makes a lot of sense. “New technology is often for the rich and they get to enjoy it before it trickles down, but it’s nice for us to be able to help the people in society that really need that discount on their electricity.”

The SolShare kit was developed in 2015 and manufactured inhouse by Allume until a rise in demand necessitated outsourcing to fellow-Victorian business Planet Innovation.