Rooftop solar smashes demand and supply records in world’s biggest isolated grid

Rooftop solar has smashed the ceiling yet again in Western Australia – the world’s biggest isolated grid – reaching nearly three quarters of electricity needs at one point and pushing “operational” demand to record lows.

New benchmarks were set on both Saturday and Sunday, according to the Australian Energy Market Operator, highlighting the rapid change in the electricity grid as solar perched on the rooftops of homes and businesses undermine the business case of fossil fuel “baseload” power.

AEMO reported last week that “operational” demand on WA’s main grid had fallen 35MW to a new low of 707MW in the middle of the day after rooftop solar provided an estimated 71 per cent of underlying demand.

On Monday, AEMO noted that the record had been broken again, on consecutive days over the last weekend, first to 683MW on Saturday and then to 626MW on Sunday, a full 11.5 per cent below the record set just a week earlier.

Rooftop solar share reaches 74 per cent

At the time of the new benchmark, rooftop solar provided an estimated 74 per cent of underlying demand, another new record.

This share is not a world record for a grid, but it is for an isolated grid of this scale. South Australia has a higher share of rooftop solar, occasionally meeting the equivalent of all its domestic demand, but that state has two links to Victoria and another being built to connect to NSW.

See also: Solar eliminates nearly all grid demand as its powers South Australia grid during day

The WA main grid, known as the South West Interconnected System (SWIS) is expected to phase out the last of its state-owned coal generators by 2028, mainly because they are dirty and polluting, and because they struggle to deal with the big bite of the energy pie taken by rooftop solar in the middle of the day.

That will pave the path for more “flexible” capacity, be it battery storage, peaking gas plants or even pumped hydro storage.

In Australia’s main grid, the impact of rooftop solar is also causing problems for the remaining coal fired power generators, which face increased costs from the stress of ramping up and down in response to the vast and still growing solar resources on the roofs of energy consumers.