The State Government plans to transform the South West’s rooftop solar panels from an uncontrolled danger to the power grid to the key to cleaner and cheaper energy.

Every month about 2000 new rooftop solar systems are connected to South West Interconnected System. Within two years on some sunny days demand for power from the traditional large power stations could drop low enough to threaten the stability of the system that serves 1.15 million customers on the SWIS.

Energy Minister Bill Johnston said there were three options to keep the system stable: restrict rooftop solar installations; fund a massive investment in Western Power’s network that would drive power prices up; or better integrate so-called distributed energy resources into the system.

“The DER roadmap sets up our pathway to that third objective," Johnston told the industry on Thursday.

DER includes what households and businesses do for themselves behind the meter, such as solar panels, batteries, electric cars and demand management technology for pool pumps and hot water systems. Front of meter DER includes small solar and wind farms, and grid-scale batteries.

Stephen Edwell, the independent chair of the Energy Transformation Taskforce that developed the DER roadmap, said WA had “stellar” renewable energy resources and should lead the way in integrating DER.

Edwell said the longer-term “big play” was “how do we bring all of these resources at the household level together to the market in an efficient way to replace thermal carbon-generated power?”

“But first and foremost, we've got to take the risk to the power system off the table.”

Perth has more cloud-free days than any other Australian capital city, and the cost of a similar-sized rooftop solar installation has halved since 2012, according to the roadmap. Already one-third of households in WA’s South-West have a rooftop solar system and penetration could reach 50% within 10 years.

While Queensland and South Australia have a higher penetration of rooftop solar than WA, they can better handle the fluctuation in solar power as their grids are connected to other states.

To avoid a system meltdown in 2022, the Taskforce has focussed on inverters: the wall-mounted part of a solar system that converts direct current power from the solar panels to the alternating current used on the power grid and in homes. Modern inverters also monitor and control the performance of the system and communicate with other devices.

This year inverter standards will be changed so new systems can react to problems in the system like traditional generators. By 2022 it is planned that new inverters will be able to manage the output of rooftop solar systems remotely.

Some more recent already installed inverters may be able to be updated remotely to meet the new requirements.

An end to the unrestricted sale of rooftop solar power in the middle of the day is likely.

The ability for systems to be controlled will allow companies to become aggregators, or virtual power plants, and coordinate a large number of systems to provide power and stability to the grid.

Energy Policy WA DER director Jai Thomas said aggregators would be “front and centre of the provision of services across the value chain.”

The 40c a kilowatt-hour net feed-in tariff, a perk of rooftop solar ownership restricted to early adopters, will end over the 12 months from August 2020.

One aggregator looking to replace these aging systems is Plico Energy, backed by Perth-based Starling Energy Group and Swiss infrastructure fund manager SUSI Partners.

Plico provides and installs solar panels and batteries for a weekly fee instead of an upfront cost.

Starling Energy managing director Brian Innes said he was happy that the roadmap would be technology-neutral and chase the lowest cost solutions.

"There are 78,000 houses about to come off a 40c feed-in tariff over the next year,” Innes said.
“If we help them make the right decision and invest their upgrades into technologies that are dispatchable and controllable and have batteries on them ... then we'll have a grid that is far more resilient,

"We're already set up to do it,

“What we've been looking for as a business is just a clear path for us to be able to negotiate on behalf of the members of Plico Energy.”

The taskforce recommended grid owner Western Power identify where battery storage could help the grid work better and expected “a variety of third-party models will emerge to provide required services to Western Power.”

Innes said he thought the private sector would deliver the services most cost-effectively.

Energy Policy WA, Synergy and Western Power will conduct an “orchestration trial” this year to test how well behind the meter DER can be centrally controlled.

The taskforce concluded that the current flat electricity tariff was increasingly unsuitable as more DER was installed, but the pandemic has delayed a planned trial of new tariffs.

New tariffs needed to encourage energy use to be moved to the middle of the day, reward investments like household batteries that benefit the entire system and ensure others are not subsidising richer consumers who can afford to install DER.

The Energy Transformation Taskforce will deliver to the Government a whole of system plan mid-year that models long term scenarios to identify the best investments in the power system.


Main Picture: Graphic. Source: Energy Transformation Taskforce