Off-peak and controlled load electricity explained

Australian households have been paying two electricity prices for decades without anyone calling it fancy. The lights and the fridge sit on the general circuit. The old storage hot-water tank, and sometimes a concrete slab or a pool pump, sit on a controlled load: a separate circuit the distributor turns on when the network would rather you used power.

People still call that "off-peak". The word now also means the cheap window on a time-of-use tariff. Mixing the two is how you "save money" by running a tank at 2am while your solar inverter stares at a dark roof.

What a controlled-load circuit actually is

Controlled load is not a discount the retailer sprinkles on the whole bill. It is hardware.

• A dedicated pair of wires from the meter to the load, commonly an electric storage water heater.
• A separate register on the meter, so those kilowatt hours are billed at a different rate.
• Switching by the distributor — historically by ripple control or a time clock, increasingly by a smart meter program — so the element is energised only in approved windows.

If you walk to the switchboard and see a circuit labelled "hot water", "off-peak" or "CL", that is the thing. If the kettle and the tank share one tariff line on the bill, you probably do not have controlled load, even if the salesperson said "off-peak".

The retailer sets the cents per kilowatt hour for that register. The distributor sets when the circuit is live. Switching retailers does not let you pick 11am to 3pm for a legacy ripple system. It might, on a reprogrammed smart meter, change how the window is delivered. Ask, in writing, before you assume.

Controlled load 1 versus controlled load 2

Names vary by network — Ausgrid, Endeavour, Essential Energy, Energex, SAPN and the rest each publish their own tariff dictionary — but the household pattern is stable enough to be useful.

Controlled load 1 is the classic overnight tank. Fewer hours, often in a single night block, at the lowest usage rate the network and retailer pair will offer. If the tank is sized for the household, it reheats while you sleep and coasts through the day.

Controlled load 2 (sometimes marketed as extended off-peak) is more hours, which may include daytime or afternoon boosts, at a higher controlled-load rate than CL1. It suits bigger hot-water demand, or households that kept running out on CL1.

Neither is "unlimited cheap power". If you plug a car charger into a controlled-load circuit without the distributor and electrician agreeing, you have invented a problem. These circuits are for nominated loads, with nominated current, on nominated hours.

Some sites still have an old off-peak 1 / off-peak 2 label on the bill. Treat that as controlled load until the fact sheet says otherwise. When you compare electricity plans, enter those kilowatt hours in the controlled-load box, not in general usage. Energy Made Easy and Victorian Energy Compare will otherwise price your tank as if it were an air-conditioner at 6pm.

How this differs from time-of-use off-peak

Time-of-use off-peak is a price that applies to general household usage during defined hours. The oven, the TV and the EV charger can all take it. The circuit stays live. You are trusted, or at least billed, to choose when to consume.

Controlled load is a switch. Outside the window the tank may have no supply. That is why a failed element is sometimes discovered on a cold Monday, and why solar households get cross: the tank cannot legally or physically sip midday solar if the contact is open.

A home can have both. Plenty of Victorian and New South Wales smart-meter sites sit on time-of-use for the house and controlled load for hot water. The bill then has four or five usage lines. That is not a printing error.

Demand tariffs add a third idea: a charge for your highest interval. A controlled-load boost that coincides with cooking can still sting on the general-circuit demand, depending how the site is wired. Interval data will show it. A pamphlet will not.

Solar households should treat overnight heat as a choice

Rooftop solar flipped the old logic. Overnight power used to be leftover coal. Now the cheap, clean kilowatt hour at a solar house is often lunchtime, when exports would otherwise earn a modest feed-in tariff.

If a storage tank still reheats at 1am on controlled load:

• You import grid energy at the controlled-load rate.
• You export surplus solar at noon for a few cents.
• You pay the daily supply charge either way.

Sometimes the controlled-load rate is so low that the arithmetic still works, especially with a large tank, a poor feed-in rate, and no way to time the element. Often it does not, particularly if you are on a solar-friendly retail plan that already cheapens daytime imports, or if you are looking at a home battery.

Options an electrician actually installs:

• A timer or solar diverter on a tank moved to the general circuit, heating while the inverter is producing.
• A heat-pump water heater on the general circuit, using less energy, timed to daylight.
• Keeping controlled load as a boost only, if the network product allows a rare top-up.

Do not cut a circuit because a podcast told you to. Look at a year of bills: controlled-load kilowatt hours times that rate, versus estimated daytime imports times the general rate, plus lost feed-in if you would have exported instead of heating. If you heat with gas, the comparison is different again — see electricity versus gas heating costs — and the controlled-load register may only be a leftover slab or a second tank.

Should you keep controlled load?

Keep it when all of the following are true:

• The tank or slab still works on that circuit.
• The controlled-load rate on your best available plan is clearly cheaper than moving the same kilowatt hours onto general usage, even after solar.
• You cannot usefully shift the load into solar hours without a messy rewire.
• The new retailer you want actually prices controlled load. Some cheap-looking offers pretend the second register does not exist.

Drop it, or rewire, when:

• You have enough solar and a diverter or heat pump to cover hot water on sunny days.
• The "cheap" controlled-load rate came with a punishing general-usage rate, and you would save more by optimising the rest of the house.
• The meter swap notice says the old off-peak product is being retired and the replacement looks like a demand or TOU structure you have not modelled.

Ask the retailer to show both scenarios on a fact sheet. Then check the same numbers on Energy Made Easy or Victorian Energy Compare. A call-centre promise that "off-peak comes with us" is not a rate.

Switching, meters and the unglamorous paperwork

Take a photo of the meter registers and the switchboard labels before you switch retailers. The NMI identifies the site; the extra register identifies the tank. If a welcome pack lists a single-rate-only product, stop.

When a smart meter replaces an old two-element meter, confirm in writing:

• Controlled load will still be switched, and in which hours.
• You will still be billed on a separate register.
• Any change to the retail tariff structure is something you consented to.

If the tank goes cold after a meter appointment, that is a wiring or programming fault, not a lesson about energy markets. Call the retailer, then the metering provider they name. If the site is left without hot water and nobody owns the job, that is a complaint, and if needed an ombudsman matter — EWON, EWOV, EWOQ, EWOSA, Energy Ombudsman Tasmania, or ACAT in the ACT.

Controlled load was a good 1990s answer to a night-time surplus. It is still a good answer for some tanks in some streets. It is a habit for everyone else. Read the second usage line on the bill as if you had never heard the word off-peak. That is usually when the right decision appears.