Your energy day: 24 hours of usage, solar, and prices
Electricity isn't used, generated, or priced evenly through the day. Understanding the daily cycle is the key to understanding why time-of-use tariffs, feed-in rates, and battery economics work the way they do.
'Why does when I use power matter?'
If you’re on a flat-rate tariff, it doesn’t — you pay the same per kWh at midnight and at 6pm. But if you’re on a time-of-use plan (and most households with smart meters are, or could be), the time of day you run heavy appliances directly affects your bill. Even on a flat rate, the underlying wholesale cost of electricity varies dramatically across the day — and retailers factor that into the flat rate they charge you.
A typical day, visualised
The chart below shows three things moving through a 24-hour day for a typical Australian household with rooftop solar: household electricity consumption (amber), solar panel generation (green), and the indicative wholesale electricity price (blue dashed line).
Morning & evening peaks
Household usage spikes when you wake up and again in the evening — exactly when prices are highest.
Midday solar surplus
Solar floods the grid around noon, pushing wholesale prices to their lowest — that’s why feed-in rates are low.
The price signal
Shifting heavy loads away from the evening peak and into the solar window saves money — this is the core of time-of-use pricing.
The four phases of the day
Overnight baseload (10pm - 6am)
Usage is at its lowest — just the fridge, standby loads, and maybe a hot water system cycling. Wholesale prices are low. This is the cheapest window on a time-of-use plan, and the ideal time to charge an EV or run a controlled load.
Morning peak (6am - 9am)
The household wakes up: showers (hot water), heaters, kettles, toasters, and hair dryers all fire at once. Usage spikes briefly and prices rise with it. This is a shoulder period on many TOU plans.
Midday solar dip (10am - 3pm)
Solar generation peaks while the house is often empty or using little. The surplus floods the grid, pushing wholesale prices down — sometimes to zero or negative. This is why feed-in tariff rates are low: there’s too much supply.
Evening peak (4pm - 9pm)
The sun sets, solar drops to zero, and households simultaneously switch on lights, cooking, heating/cooling, and screens. This is the most expensive window of the day — the peak rate on your TOU plan is designed to reflect this reality.
Why time-of-use tariffs exist
Time-of-use pricing isn’t arbitrary. It reflects the real cost of generating and delivering electricity at different times of day. When demand is high and solar is gone (the evening peak), retailers are buying expensive wholesale power. When demand is low or solar is flooding the grid (overnight and midday), wholesale power is cheap. TOU tariffs pass that price signal through to you — giving you an incentive to shift heavy loads away from the expensive window.
The savings opportunity
Why solar feed-in rates are low
Many solar owners are frustrated that their feed-in tariff is so much lower than what they pay to buy electricity. The chart above explains why: solar generation peaks at exactly the time wholesale prices are at their lowest. Your retailer is buying your exported solar at the midday wholesale price (roughly $20–40/MWh, or 2–4c/kWh) and selling you power in the evening at a much higher wholesale cost. The gap isn’t a rip-off — it’s a reflection of when supply and demand meet.
This is also why self-consumption (using your own solar instead of exporting it) is worth more than exporting. Every kWh you use from your own panels during the day is a kWh you don’t have to buy from the grid at 30c+ that evening.
Why it matters
The daily energy cycle is the foundation of almost every energy decision you can make: whether to switch to time-of-use pricing, when to run heavy appliances, whether solar or a battery makes financial sense, and how to get the most from them if you do. Once you see the shape of the day, every other decision becomes clearer.
Next step
Everything on this page depends on one piece of technology: the meter that records when you use power. Find out what a smart meter is and why it matters →