Who has the cheapest power of all?

The price of power in Tauranga is about to be shaken up, as power companies announce price hikes to coincide with the incoming Emissions Trading Scheme (ETS).
So how much can average Tauranga households expect to pay? 
The Bay of Plenty Times used an online Consumer price comparison calculator to find out which power provider was the cheapest. The variation between some companies was  several hundred dollars.
None of Tauranga's providers have the same tariff rate so the  calculator was used to estimate annual costs from all of Tauranga's power providers - Mercury Energy, Energy Online, Genesis Energy, Nova Energy, Contact Energy, Empower, TrustPower and Meridian Energy.
The search involved two hypothetical case studies - an elderly couple and a young family. Both households used electronic heating and cookware.
The young family was estimated to pay between $1765 and $2421 a year while the elderly couple faced costs of between $1304 and $1853. In both cases, Mercury Energy was the cheapest provider while TrustPower was the most expensive. Plans and discounts for electronic payment, or prompt payment, were included in the results.
Mercury Energy and Contact Energy announced this week they would raise prices 3.3 per cent and 3.2 per cent respectively from July 1, when the ETS sees the introduction of a price on greenhouse gas emissions.
Mercury Energy communications manager Marie Hosking said the decision to raise prices was independent, "just like any other retailer".
 She said the hike  reflected the wholesale market.
TrustPower communication relations manager Graeme Purches said the  calculator used was a guide, and did not reflect savings made by loyal "long term" customers. "It's an instrument, but a blunt instrument."
Mr Purches acknowledged TrustPower had comparatively high quotes but said it provided the best overall service and gave back to the community.
Tauranga TrustPower customers are beneficiaries of Tauranga Electricity Consumer Trust (TECT), a major shareholder in TrustPower. It distributes some of the dividends it receives from TrustPower back to beneficiaries as payments.
TrustPower's TECT cheque is not taken into account in the estimates as it is not guaranteed, said Consumer research and testing manager Hamish Wilson.
"This cheque is like a dividend, paid out if they have a good year," he said.
Mr Wilson said  people  should shop around, and research what plans were available and their hidden costs. The most common trap when choosing power companies was line charge, he said.
That is a daily charge added to the bill at the end of the month, that could add $30 to the monthly power bill. "Most companies quote cost per unit but this can be quite misleading if they don't include GST and the line charge," Mr Wilson said.
The  calculator is free to use through the Consumer website and is supported by the Ministry of Consumer Affairs. It is available at www.consumer.org.nz/powerswitch
CUT YOUR BILL
Smart ways to reduce your household power consumption:
Concentrate on water and space heating, as those account for between half and three-quarters of the total energy use in most households.
Draught-proof doors and windows.
Seal off open fireplaces when not in use.
Maximise the sunshine into your home during winter by keeping curtains open during the day and cut back trees that shade north-facing windows.
Use thermostats and timers on electric heaters.
If your hot water cylinder doesn't have a "Grade A" label, wrap it with a cylinder blanket.
Use a low-flow shower head to supply water at six to nine litres per minute.
Fill the kettle or jug from the cold tap and heat only the amount needed.
Turn lights off when leaving a room.
Use a microwave or pressure cooker where possible.
Buy energy-efficient appliances.
See Saturday's Bay of Plenty Times for table comparing prices.