The Duck Curve Explained: How Home Batteries Can Support Australia’s Energy Market

The term duck curve (sometimes referred to as the solar duck curve) was first used in California to illustrate how increasing rooftop solar changes net electricity demand across the day. Essentially, the curve shows a dip in grid demand during the middle of the day when solar production is at its peak, followed by a rapid rise in demand in the late afternoon and evening as people return home and the sun sets.

Electricity prices are directly influenced by supply and demand. During periods of high solar generation, such as around midday, the abundance of electricity can push wholesale prices down, sometimes even into negative territory. Conversely, in the evening, as solar production fades and demand rises sharply, wholesale prices can spike.

This creates a daily pattern of price volatility that can be confusing for households and challenging for grid operators. Homeowners might see that their solar exports are generating minimal revenue during the day, yet they still pay high prices for electricity once the sun goes down. For retailers and generators, the duck curve represents both an operational and economic challenge: they must balance supply and demand across the day while managing financial risks created by the steep swings in wholesale prices.

Feed-in tariffs were originally created to reward early solar adopters. Back then, solar was rare, and the grid genuinely benefited from extra daytime energy so retailers paid very generous rates.

Today, the situation has completely flipped.

With millions of homes exporting solar at the same time, feed-in tariffs are falling fast because:

• There’s now too much solar in the middle of the day

• Wholesale electricity prices often drop to near zero or even negative at midday

• Retailers can’t pay more for solar than what the market is actually worth

• More supply = lower value for every exported kilowatt-hour

This downward trend is expected to continue long-term. The duck curve makes it inevitable. The deeper the midday “solar belly,” the lower the export value.

A home battery turns this challenge into an opportunity by capturing excess solar at zero cost and shifting it to the high-value evening peak. It means you use more of your own energy, rely less on the grid, and get far better savings than relying on feed-in tariffs alone.

Home batteries are emerging as one of the most effective solutions to the duck curve. By storing excess solar energy during the day and releasing it in the evening, batteries help reduce the extremes of the duck curve while providing multiple benefits to households and the electricity system.

During the day, batteries charge using surplus solar energy, absorbing electricity that would otherwise be exported to the grid at low or negative prices. This process lifts the “belly” of the duck, reducing curtailment of solar and increasing the utilisation of renewable energy. In the evening, batteries discharge stored energy to meet household demand, reducing reliance on the grid and softening the sharp rise in demand or the “neck” of the duck.

When aggregated across thousands of households, this behaviour can significantly reshape the net-load profile seen by the grid, reducing the need for fast-start peaker plants, lowering wholesale price spikes, and contributing to a more stable and reliable electricity system.

Beyond reducing price volatility and evening peaks, home batteries offer several other benefits:

Despite the clear benefits, there are some challenges and risks associated with widespread battery adoption:

To maximise benefits, policymakers can introduce measures such as dynamic pricing, time-of-use tariffs, virtual power plant frameworks, improved visibility of distributed energy resources, and equitable incentive programs.

Looking ahead, Australia’s electricity system is likely to become increasingly decentralised, with millions of small, customer-owned batteries working together to support grid operations. In this vision:

• Virtual power plants (VPPs) coordinate thousands of batteries to provide grid services, invisible to the homeowner but valuable to the system.

• Networks act as platforms that procure flexibility services rather than relying solely on centralised energy generation.

• Households gain control over energy costs while simultaneously contributing to a more stable, low-carbon grid.

Over time, this distributed approach could significantly reduce reliance on fossil fuel generators, lower emissions, and enable a higher share of renewable energy in the mix, fundamentally reshaping how Australia produces and consumes electricity.

The duck curve reflects a structural shift in how Australia generates and uses electricity. As rooftop solar continues to grow, the gap between midday oversupply and evening demand becomes more pronounced, placing pressure on pricing, grid stability, and long-term system planning. Home batteries offer a practical, scalable solution by storing excess solar when it has low market value and shifting it to the periods when households and the grid need it most.

At 1KOMMA5°, our focus is on helping Australians make the most of this transition. We offer solar and battery systems that deliver strong long-term performance, greater energy independence, and meaningful bill savings. More importantly, they position households to play an active role in the shift toward a smarter, decentralised, and renewables-driven energy system.

For homeowners looking to future-proof their energy use, storage is quickly becoming an essential part of the modern solar system and a straightforward way to support a cleaner and more resilient electricity grid.