A plain-English look at wholesale electricity prices across NSW, QLD, SA and VIC over the past year, what the patterns mean for your bill, and a calculator that estimates the right-sized solar and battery system for your home based on real market data.What Electricity Really Costs — And What Solar + Battery Could Save You
What is the "wholesale market", really?
Every bit of electricity used on Australia's east coast grid is bought and sold on a market run by the Australian Energy Market Operator (AEMO) — think of it like a stock exchange for power. Generators (coal, gas, wind, solar, batteries) offer to sell electricity, and the price is set every few minutes based on how much power is available versus how much everyone wants right now.
When there's plenty of cheap power around — like the middle of a sunny day, with millions of home solar panels flooding the grid — the price drops, often below zero. When the sun goes down and everyone gets home, turns on the aircon, cooks dinner and charges the car, demand spikes and supply gets tighter, so the price can jump dramatically.
Most households never see any of this — your retailer charges a flat rate and absorbs the difference. Every state below shows the same basic shape, but the size of the swings is very different depending on how much rooftop solar and wind is on that state's grid.
How the Four States Compare
All four states' daily price curves, overlaid — this is the fastest way to see who swings hardest and who pays the most at peak.
And the headline numbers side by side, 1 Jul 2025 – 11 Jul 2026:
See What This Looks Like for Your Home
The numbers on this page are real market data — but every home's roof, usage and appliances are different. Our team will size an exact system for your address, on your actual usage, and walk you through the real numbers before you commit to anything.
Get Your Free QuoteTwelve Months of Prices, Day by Day
The "Solar Dip and Evening Squeeze"
Average price for every half-hour of the day, averaged across the whole year.
Prices by Month
How Often Each Price Range Occurs
The Impact on Your Power Bill
Fixed retail rates exist because retailers need to cover themselves for the rare but painful price spikes. That protection is built into your rate every single day — including the 70–90% of the time prices are actually low or negative.
Because wholesale prices are frequently at or below zero around midday in every state on this page, feed-in tariffs during those hours are typically minimal — this is why exporting solar in the middle of the day is worth so much less than using it yourself or storing it.
If your household load — or your EV charging, or your battery discharge — lines up with the late-afternoon and evening price spike, that's the highest-value window of the day, for better or worse.
SA sees negative prices nearly a third of the time and the sharpest spikes of any state here — that's exactly the kind of volatility a well-designed solar and battery system is built to profit from rather than be exposed to.
How We Design Systems Around the Wholesale Market
We don't design solar and battery systems just to "cover your usage" — we design them to actively work the daily price pattern shown above. In practice, that means building automation into the system from day one rather than relying on you to watch prices manually.
Your battery and inverter are configured to receive real-time and forecast price signals through a smart controller, so charge and discharge decisions are made on actual market conditions, not a fixed clock.
Your battery is set to charge when prices are low or negative (typically the midday solar trough) and discharge when prices climb toward the evening peak — capturing the spread between the cheapest and most expensive parts of the day automatically.
Battery capacity and export limits are sized with the evening price window in mind, since that's consistently where the value is concentrated — rather than sizing purely around your average daily consumption.
Because midday export can be worth little or nothing under wholesale pricing, we configure systems to prioritise self-use or storage during those hours rather than exporting into a near-zero or negative price.
Threshold alerts flag genuine spike days, and sensible sizing limits downside exposure — so the system captures upside from price swings without leaving you exposed to a runaway bill on an extreme day.
The calculator below uses this exact approach — the real half-hourly price pattern for your state — to estimate the system size and savings that make sense for your household.
Solar + Battery Savings Calculator
Enter your rough usage and we'll size a system and estimate what it could save — based on the actual wholesale price pattern for your state over the past year.
How we calculated this
Our goal is always a $0 grid bill first. We size solar and battery to cover your daytime usage directly and store enough to cover your evening/night usage too, using your state's typical solar generation hours. Your new bill shown above is what's realistically left over (mostly the fixed daily supply charge, which no solar system removes) — it won't be exactly $0 every single day, but it's designed to get as close as possible.
On a wholesale-exposed plan, we then size the battery bigger again — to roughly 4/3 of your total daily usage — so that after fully covering your own overnight usage there's genuine surplus left to sell back to the grid between 6-9pm, crediting your energy account. The "how big a battery" comparison line above shows what a battery sized only to zero your bill would cost, versus the bigger trading-optimised system we recommend, so you can see the extra investment and what it buys you.
We apply an 82% real-world capture factor to account for cloudy days, winter generation and seasonal variation — this isn't a "perfect sunny day" number. Remaining grid imports during the evening peak are priced at your state's actual average 6-9pm wholesale price, midday exports at your state's actual (often near-zero) midday wholesale price, and the trading credit at your state's real 6-9pm peak price less a 10% retailer allowance — all pulled directly from the AEMO data on this page, not a flat assumption.
The "smart timing" bonus shows the extra value captured specifically by discharging your battery into the evening peak rather than at a random time. We've kept system pricing out of this page deliberately — the exact cost and payback depend on your site, roof and equipment choice, so those numbers come from a conversation with our team.
Beyond the numbers: a bigger battery also means more blackout backup and less exposure to price spikes, which isn't reflected in the dollar figures above.
This is an indicative estimate for planning purposes, not a formal quote. It doesn't include government rebates, EV charging, seasonal load changes or your specific roof/shading conditions. Get in touch for a proper site assessment and accurate numbers for your home.