Saturday, October 15, 2011

Adventures in Electricity.

Our power bill was getting huge. We were paying $350/month, and that was in the summer. Winter bills would be considerably larger. It was well past time to do something about it.

First up, change electricity providers. In New Zealand, Consumer NZ researched all of the electricity providers and put up a web site, Powerswitch. Now, according to Powerswitch, I was with the most expensive power company (Contact Energy). So, I switched to Powershop. They weren't the cheapest, Meridian Energy is the cheapest, but Powershop had amazing reviews. I also wanted a smart meter so that I could easily track our usage, and Powershop makes them available.

So, I switched to Powershop. According to PowerSwitch, I would save $675 on a bill of $4066, or >15%!

Side comment: Make sure to provide a final reading to your provider. They have a habit of over estimating your power usage to keep your as a customer as long as they can - you pay the estimated final reading, not an actual reading.

In New Zealand, there are different ways of saving money when buying electricity. The first and easiest is to sign up for ripple control. When you sign up for this, in times of peak power demand, the power company will turn off your water heater. If you give them this ability, they will discount your power by ~10%. Sounds like a good idea, except for one problem - it doesn't work. I repeatedly had the ripple controller turn off the water heater and then fail to turn it back on. Nothing is more unpleasant than getting into the shower and there not being any hot water, calling a plumber, who tells you the problem is electrical, and then calling an electrician who tells you the problem is the lines company. TWICE.

When that happened, I turned off ripple control, and I will never turn it back on.

Powershop gives you a different way of saving money. They offer time of day charging. This provides a discount on electricity between the hours of 11PM and 7AM. It has the same effect as ripple control, only it's under my control instead of the lines company's.

With the Powershop "All Inclusive" plan, they currently charge 23.93c/kwh. This is for the ripple controlled power. Then there is uncontrolled at 26.23c/kwh, that's ~10% more.

However, if by switching to Day/Night Uncontrolled, I'm paying 24.07c/kwh day and 15.17c/kwh night. That means that as long as I shift a certain amount of power to the night, I end up saving, and don't need to keep ripple control. The magic ratio is:

23.93 = 24.07 * x + 15.17 * (1-x)
23.93 = 24.07x + 15.17 - 15.17x
8.76  = 8.9x
0.98  = x

That means that as long as I move at least 2% to my night plan, I'm better off. Seems strange, the service rep indicated that the magic number was 10%.

I switched plans, and installed a smart meter, which cost $165. The savings from 26c/kwh to 24c/kwh (the minimum savings), with an average usage of 1600kwh/month, I have a payback of:

2c/kwh * 1600kwh = $32/month
$160 / ($32/month) = 5 months.

five months! That's pretty kick-ass in anyone's book.

To recap:

  1. Shop around. You can save a tonne of money with another provider. Switching is free and easy, just head over to
  2. Change plans. Investigate day/night plans, particularly if no one's home during the day,
  3. We're at a savings of >25% from where we started, with more to come.

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