The only electricity concepts you actually need
You don't need to know how electrons work. You need to know what costs money, what the numbers on your bill mean, and what changes when you add solar or an EV. That's what this page covers.
Everything at home runs on the same supply
Every socket in your house delivers the same thing: 230 volts of alternating current (AC). What makes your air conditioner cost more to run than your phone charger isn’t a different type of electricity — it’s how much power each appliance draws from that same supply.
Power is measured in watts (W) or kilowatts (kW). The bigger the number, the faster that appliance is using energy — and the faster your meter is ticking.
What actually costs money
Your bill doesn’t charge you for having appliances. It charges you for running them. Specifically, it charges for energy — power multiplied by time — measured in kilowatt-hours (kWh).
Same kWh, very different appliances
2 kW heater for 1 hour
Uses 2 kWh — costs about 60c
TV for 20 hours
Also uses 2 kWh — also costs about 60c
LED light for 200 hours
Also 2 kWh — also about 60c
At ~30c/kWh. The heater burns through the same energy in 1 hour that the LED takes 8+ days to use.
This is the single most useful thing on this page: high-power appliances running for a long time are what drive your bill. A 2.5 kW air conditioner running 8 hours a day costs more than everything else in your house combined.
The big hitters in a typical home
| Appliance | Power | Typical daily use | Daily cost |
|---|---|---|---|
| Air conditioner | 2.5 kW | 6–8 hours | $4.50–$6.00 |
| Electric hot water | 3.6 kW | 3–4 hours | $3.25–$4.30 |
| Pool pump | 1.5 kW | 6–8 hours | $2.70–$3.60 |
| Clothes dryer | 2.4 kW | 1–2 hours | $0.72–$1.44 |
| Fridge | 0.15 kW | 24 hours (cycles) | $1.08 |
| TV | 0.1 kW | 5 hours | $0.15 |
| LED light (10W) | 0.01 kW | 8 hours | $0.02 |
At ~30c/kWh. Heating, cooling, and hot water typically account for 50–70% of a household’s electricity bill.
Your switchboard: the traffic controller
Every wire in your house connects back to your switchboard (the grey box, usually in your garage or hallway). Inside it are rows of circuit breakers — each one protects a different group of circuits: lights, power points, oven, hot water, AC.
If too much power is drawn through one circuit (say, you plug a heater and a hairdryer into the same group), the circuit breaker trips and cuts the power to that circuit. This is a safety feature, not a fault — just switch off one of the appliances and reset the breaker.
Why this matters for solar and EVs
AC vs DC — the one thing worth knowing
Your wall sockets deliver AC (alternating current) — the standard for power grids worldwide. But solar panels and batteries produce DC(direct current). An inverter converts between them.
Your grid supply
230V AC from the grid → your switchboard → your sockets and hardwired appliances. This is what your meter measures and your bill charges for.
Solar + battery
Solar panels produce DC → inverter converts to AC → feeds into your switchboard. Batteries store DC → inverter converts when you need it. You lose a small amount of energy in each conversion.
Three numbers, three meanings
You’ll see these units on bills, solar quotes, and appliance labels. Here’s what each one actually tells you:
Volts — the pressure
Fixed at 230V in Australian homes. You never need to think about this — it’s the same everywhere in Australia.
Amps — how much flows
A kettle draws ~8 amps, a phone charger ~0.1 amps. Your circuit breakers are rated in amps (typically 16A or 20A per circuit) — that’s the maximum flow the wire can safely handle.
What to do with this knowledge
You don’t need to memorise any of this. The practical takeaways:
- Check the wattage of anything you run for hours — AC, heaters, pool pumps. That’s where the money goes.
- Heating and cooling dominate — if your bill spiked, it’s almost certainly seasonal.
- Turning off lights saves almost nothing — LED lights use so little power that switching them off barely moves the needle. Don’t feel guilty about lights; focus on the big stuff.
- The kW number matters — on your next bill or solar quote, look for it. The next page explains kW vs kWh in detail.