Guest Post – My route to a lower power bill – Part 1


I purchased a 3KW Micro Inverter Solar system from the sponsor of Map of the Day, What Power Crisis, back in March and now it’s been running for a while I thought I’d share my experiences over a few articles. Although What Power Crisis did me a decent deal on the system, I’m not being paid to write this.

I bought the system with 3 aims:

1) Cut my power bill which was heading towards $2800pa

2) Get payback on my investment within 10 years

3) Not make life miserable by compromising on comfort and convenience.

I’m not a believer in the great man-made global warming/climate change conspiracy so changes in CO2 emissions didn’t factor into my decisions. Even if this was a concern, much more than half of New Zealand’s generation already comes from renewable sources, so replacing one renewable source with another, especially as it has to be manufactured in the first place, no doubt using fossil fuels, won’t make that much of a difference in my book.

Having run the system since 25th March with an extra couple of panels added recently I’m on track to achieve my targets.

I never measured the power use before I embarked upon renovations so the $2800 is the before-solar cost of a renovated 60’s house, with a DIY solar-heated pool setup and a new well insulated small spa. I can’t quantify how much cheaper the house is to run per month due to the renovations, but it is much more comfortable than before with no mould or damp. We usually wear T-shirts all year round, and the lowest recorded temperature without heating in the living area is 16 degrees.

Cutting power use is the cheapest way to shrink a bill! ??

Most people pay their power bill every month without having any idea where their power goes. If you are going to get that power bill under control with or without solar you need to work out:

  • What’s using the power?
  • When is it being used and can I change this to during the day?
  • Am I getting any benefit from what is using it?

Rather obviously there’s no point in having a massive solar system, generating heaps of power in the day when you sell it to the grid in summer at a pitiful 7 cents per Kilowatt Hour in the day to then buy it back later in the day when sun has set for around 34 cents per Kilowatt Hour (Low User Tariff.)

The biggest power hog that you can do something about is usually the Hot Water Cylinder. Newer models are better than old ones in terms of heat loss, but they all lose heat and often thermostats are set too high. According to the building code the water should be heated to 65 degrees C to keep legionnaires disease at bay, but in reality most thermostats are set much higher than this. As a rule the hotter the tank is compared to the surrounding air the greater the heat loss, and the more money you have to pay to keep the water warm before you even use any.

The first thing I did was turn the thermostat down to 65, the second thing I did was get a timer to restrict the heating time to 3 hours a day in the early hours of the morning so the water was hot for a morning shower, but not kept warm all day when nobody was using it. The water was still warm later in the day, although not as warm as first thing.

Later after much research I swapped the elderly 180 litre tank for a new 300 litre Coopers Stainless Steel one with the latest insulation. Despite this it was still warm to the touch so I got a cylinder jacket from Bunnings and put that around it. I also insulated the cupboard it was in and stood it on 50mm plywood to again limit heat loss.

At this point the timer was turned down to 2 hours a day and looking at Meridians My Energy it didn’t always need the full 2 hours. Granted this is an extreme way to sort this, but we intend living here for a very long time, the plumbing was pretty shot, and we were renovating.

We already had heat pumps for heating so apart from a few tweaks to a pretty average install done by the previous owner the heating was sorted.

The next item on the energy hog hit list was the pool pump, this came with the house and announced its presence by dimming the lights and making an awful noise, clearly it didn’t have long to go before it failed. As the rest of the equipment was ancient and worn out the whole lot had to be binned. I replaced the oversized 1.5hp pump with a correctly sized 0.75hp model, and at the same time minimised the restrictions in the pipe work by removing as many sharp bends as possible. This dropped the power used by around 40%/$200pa, whilst the water remained crystal clear.

The trans-Tasman ticket clippers ensure the latest energy saving pumps aren’t cost effective so that was as far as I could sensibly go for now.

The next thing to do was replace the leaky, steamed-up-in-winter, aluminium windows with UPVC double glazing. I also added better insulation to the roof space and under the floorboards. After pulling furniture out and discovering big draughts from the basement below, I pulled off all the skirting boards and filled in the gaps beneath them where the floorboards ended and the Gib began. This made the house much warmer and nudged the power bill further down.

The final thing, apart from minimising draughts, was replacing the 8 down lights with normal fittings. According to BRANZ the air leakage from just 4 down lights doubles the heat needed to keep the same temperature in a room so they had to go.

Up until now I’d dismissed solar as a waste of money, however with recent price reductions I decided to give it another look.

More in part 2