Recent converts to residential solar in some regions might look over their fences at owners of older systems and envy the fact that their neighbours earn revenue for far higher levels of exports than they do. As rooftop PV became more and more popular in some states limits were placed on how much energy could be sent back into the grid so that voltage levels didn’t go haywire.

But system owners who can’t export their surplus solar energy back to the grid due to constrained networks will soon be able to enter the market thanks to a new project led by SA Power Networks.

A 12-month field trial will test a new flexible solar connection to up to 600 rooftop PV customers in South Australia and Victoria who live in areas where the network is constrained due to very high levels of rooftop solar. The aim is to provide trial customers with an alternative to the zero or near- zero export limits that apply in these areas.

To achieve this, the project will deploy new flexible connection technology that enables inverters to automatically adjust export limits every five minutes based on signals received from the distribution network.

SA Power Networks is partnering with AusNet Services who will lead the Victorian trials, along with inverter manufacturers Fronius, SMA and SolarEdge and energy management provider SwitchDin. The Australian Renewable Energy Agency will contribute $2.09 million in funding.

Power balance

To avoid exceeding the technical limits of the grid, some energy networks impose zero or near-zero energy export limits on new solar systems in congested areas. Late adopters of solar, who in 2019 and this year account for about 4GW of new generation, do not see the same returns from their investments as owners of older systems.

By enabling customers’ smart inverters to automatically adjust the electricity exported by a rooftop solar system to match the available capacity of the grid, the $4.84 million trial will give customers in constrained areas the opportunity to sell surplus solar energy. Systems will only reduce exports during peak demand days instead of being permanently limited.

If the trial is successful, this approach could create a new solar connection agreement which could be adopted by any compatible solar inverter product and any network across Australia. 

“The electricity distribution network has a limited capacity to accommodate reverse power flows when rooftop solar systems export surplus energy to the grid in the middle of the day,” ARENA chief executive Darren Miller said.

Less than 10% of rooftop solar systems operate with smart control systems, Miller said. “If the trial is successful, it should help more customers sell more of their energy into the market and benefit from cost savings on their energy bills.”

The project will refine and develop the technologies and customer connection service to the point where it could be offered as a standard service to all customers installing solar.

SA Power Networks general manager strategy and transformation Mark Vincent said the network hopes to double the amount of solar it can accommodate by 2025. “We are looking at smart solutions, rather than expensive network capacity investment, to help make it happen.”