The 3 tariff options are A11, T33, T31.
A11 (Peak tariff)
This is your normal power that is turned on 24 hours a day, or electricity on demand. The highest cents per kw charge at approximately 21c per kwh (depending on your energy retailer).
T33 (Off Peak tariff)
The electricity to your hot water system is turned on for 18 hours a day, and will be turned off for 6 hours per day during peak periods. This usually occurs around 4pm – 8pm but is dependent on your provider and subject to daily change. You need at least a 125 ltr hot water system to be connected to this tariff. Usually this tariff is approximately 17c per kwh (depending on your energy retailer). This is the recommended tariff for a solar hot water system or a heat pump.
T31 (Off Peak tariff)
The electricity to your hot water system is turned on for 10 hours per day during the night time only. It heats your system without raising the peak demand. You will need at least a 250 ltr hot water system to be connected to this tariff. This is the cheapest of all tariffs at around 11c per kwh (depending on your energy retailer). This is the recommended tariff for an electric hot water system.