Case study: Barry, Sunshine Coast

How Barry turned his Sunshine Beach home into an evening power station

The results 

• Most recent bill: a $179.52 net credit (after all electricity, supply and other charges) 

• Price Efficiency Adjustment has improved every billing cycle from −8.4c to as much as −13.9 c/kWh, effectively lowering the rate Barry pays for electricity by that much. 

• Runs a 40kWh battery as an active arbitrage asset, charging at the midday wholesale low and exporting into the Happy Hour evening peak. 

At a glance 

• Location: Sunshine Beach, QLD 

• System: 17kW solar + Sigenergy SigenStor (40kWh storage, 20kW three-phase inverter), installed by Celtic Solar 

• Plan: Flow Power Happy Hour 

Barry and his partner live in a three-storey home at Sunshine Beach, with their adult children coming and going. It’s a busy household, electric hot water, air conditioning, an elevator, and a pool with both a filtration pump and a heat pump. Overnight the house draws around 10kWh, and daytime demand climbs whenever the pool heating is running. 

In May 2026, Barry added a 40kWh Sigenergy battery alongside his 17kW solar array. He’d done the sums: a standard flat-rate plan with a token feed-in tariff would waste most of what a battery that size can do. “Flow’s wholesale-linked pricing was the drawcard,” he says, particularly the Happy Hour peak export window and the Price Efficiency Adjustment (PEA). Together, they let him run the battery as an active arbitrage asset rather than a simple backup. The 20kW three-phase inverter is central to that: it lets the battery push out at full power into the evening peak, rather than trickling its charge away. 

Charging with a plan 

Barry’s day runs on a simple rhythm. Solar covers the house and fills the battery through the day. On low-solar days, he tops up from the grid at midday, when wholesale prices are typically at their lowest. Then, during Happy Hour’s export window, the battery discharges at full power into the evening peak, when export rates are highest. 

He keeps a 40% discharge floor so there’s always enough charge to carry the house overnight until the next morning’s solar takes over. “I watch the price chart in the Flow app and top up the battery from the grid only when spot prices are at their floor,” he says. 

The approach keeps evolving. Barry has already shifted the household’s grid consumption into the midday wholesale trough and set the battery to carry them through the night, so they rarely draw from the grid in the early hours. Next on his list: automating the pool heat pump so it only runs once the battery is full. 

A bill in credit 

Barry’s latest bill recorded a $179.52 net credit after electricity and supply charges, price efficiency adjustments and export credits. In other words, over that billing period what the household earned from well-timed exports outweighed everything it drew from the grid. 

Barry tracks his progress through his PEA, which reflects how well-timed his energy use and exports are against wholesale prices. Since switching, it has improved with every billing cycle as he’s refined his approach from around −8.4c to −11.8c/kWh on his earlier bills and to−13.9c on his latest invoice. 

“It’s the only retail model I found that rewards you for being smart about when you use and sell power, rather than just how much. Since switching, my PEA has improved every billing cycle as I’ve refined my strategy,” Barry says.