Going solar – David, ten years on

I recently received an unexpected email from David, who was good enough to write about his rooftop solar power installation for Green Path ten years ago:

As I was cleaning out our filing cabinet (yes, still have one of those!) I found all of our power bills back from when we first had solar installed. I crunched the numbers out of curiosity and found that in solar credits, we saved $7594 over the last 10+ years. This doesn’t include the offsetting of power (e.g. using the power off the roof during the day); that’s about $3000 worth. Given our 1.5 kW solar panels were only $3300 at the time, that’s not a bad return.

Continue reading “Going solar – David, ten years on”

Put Solar On It! (2)

Solar power has been going gangbusters since my previous post under this title (2014) and an update of it is well overdue. This isn’t it, however. What I want to do here is talk about domestic solar power, and specifically its advantages here in North Queensland, via four small projects which came out of our own move from one suburban Townsville house to another two years ago.

I will go from smallest to largest.

Hall Lighting

The new house is a low-set, 1950-ish cement block home pleasantly surrounded by trees. That makes it much darker than our old high-set home, and its double-fronted layout means that the central hallway gets no direct natural light at all.

We had to choose between running lights all day, every day, and putting in a small skylight. Initial quotes for a skylight (Solatube, basic model) were around $750 with, of course zero running costs for about 10 hrs/day of adequate light, 365 days/yr. Could we do better?

Continue reading “Put Solar On It! (2)”

Greening our homes

In a Reef HQ Aquarium internal newsletter in November 2012, Sascha Thyer (Technical Operations Manager) detailed the greening programme which cut the aquarium’s energy costs by 50% and, just as importantly, reduced CO2 emissions by nearly 2500 tonnes over five years.

I wondered if we could apply similar strategies to our own homes. True, we haven’t got the expertise or resources of Reef HQ; then again, our homes are much simpler and plenty of information is widely available. True, a home doesn’t use 2400 MWH per year, as Reef HQ did; but our homes (using an average of 25 KWH per day, Ergon’s figure) use about 9 MWH apiece per year and that does add up – 250 homes will use as much as the Aquarium did before the programme.

Worth tackling? Definitely. I went through her article, ‘translating’ it point by point into domestic terms, and this is the result. Quotes from Sascha’s article are in italics.

Before 2006, ReefHQ had no formal strategies for the sustainable use of its business resources. Motivated by concerns about Climate Change and rising energy costs, a small working group … convened to conduct an internal audit of infrastructure and processes.

Staff behaviour, procedures and maintenance were addressed first. ReefHQ staff were trained to avoid wasting energy by closing doors and turning off unused equipment.

Can we do that? Yes, of course. We might need to look quite carefully to notice some of our less-than-ideal habits – lights left on, TVs left on standby, etc – but it’s a cheap and simple process.

The building air-conditioning setpoint was raised from 23C to 24.5C.

Every degree higher that our aircon is set at saves about 10% of its running costs (see note 1). It’s much cheaper to run it at 24 – 25C than at 20C, and you will be more comfortable outdoors in what you wear indoors as well. Can we do that? Yes, of course.

Some minor building works were also undertaken, including the installation of window tinting and removal of dilapidated skylights.

Reducing leakage of cooled air to the great outdoors (door strips, windows seals, etc) will save on running costs. Reducing the flow of the sun’s heat into our house by shading or tinting windows will help too. Can we do that? Yes, of course.

These simple measures resulted in a 13% reduction in power consumption.

Can we do that well at home? Probably.

Although ReefHQ has very good in-house expertise, formal audits were required to secure the necessary funding …

We probably don’t need to go that far but the service is available if we want to.

Deciding where to start is not simple even if the big offenders are clear, as the decision is also governed by the ability to implement the change (e.g. there may be little budget to make changes).

That sounds familiar!

Following the initial operational changes, ReefHQ moved on to lighting … after three years, the results for implementation of energy-efficient general lighting have been excellent. Overall energy consumption was reduced by 3.1% and ReefHQ is over $10,000 ahead.

We may not do so well at home, depending on how far we have already gone with changing from incandescents to CFLs or LEDS, but anyone still using the once-fashionable low-voltage downlights should be able to save heaps (see note 2).

ReefHQ completely rationalised the pumping systems including pump and piping design, and pump choice. … A cost benefit analysis of the smaller pumps revealed that the ‘cheap’ pump was costing $20,000/yr more than the most expensive pump on the market.

The pumps which maintain healthy water flows through ReefHQ’s tanks use much more power than our pool pump, so we won’t gain nearly so much here. However, a new pool pump is worth looking at. Ergon is offering cash-back bonuses for new pumps and for changing to the off-peak tariff.

With the capital funds injection in 2010, ReefHQ undertook a major upgrade to the main building air-conditioning system. … The new water-cooled system is 1.7 times more efficient than the old air cooled system, and it … is expected to reduce ReefHQ’s overall energy demand by more than 23%.

Our air-con probably represents 50% of our power bill so any improvement is going to make quite a big difference to our bottom line. If any of my readers is leaving an air-con running all day in an empty house so that it’s cool to come home to, please, please invest in a time-switch! No matter how expensive it is to install, you will get your money back in a few months, if not weeks. Other than that, follow previous recommendations: set it at 25C instead of a lower temperature and plug gaps around windows and doors.

Solar panels on Reef HQ street frontage
Where to put solar panels when you run out of roof space: this awning on the North side of ReefHQ aquarium is roofed entirely with PV panels.

The world’s largest living coral reef aquarium is now registered as a solar power station … [with] a 160kw peak output.

Can we do the same? Of course. Payback times for solar power systems have increased as the feed-in tariff has been reduced from 44c/KWH to a miserly 8, but solar is still worth looking into, especially if your daytime power use is a significant part of your bill. See Going Solar here on Green Path for more information.

There are some things Sascha’s article for ReefHQ did not look at:

  • Insulation will save cooling costs two ways – you will need the air-con less often and it will be cheaper to run when you do need it. Painting the roof with a reflective coating (which has an insulating effect as the coating is a very poor conductor of heat as well as reflecting the heat) is endorsed as one of the most cost effective measures by the Townsville City Council. It also has the added benefit of extending the life of your roof. Instead, or as well, it is possible to insulate the ceiling with batts and/or line the roof with silver tar-paper.
  • Hot water is a large energy-user in most homes. Solar hot water systems are excellent value in our climate (I only turn on the booster about ten days per year!) and if you haven’t got the roof space, the new heat-pump systems use only 30% as much power as the old kind (note 3). Washing your clothes in cold water saves a lot of power and money, and of course you will switch the HWS to off-peak, won’t you?
  • Clothes dryers are very expensive to run and most of us can use the low-tech solar solution (yes, a clothes-line) instead, most or all of the time.
  • LED televisions are very energy efficient and use half the power of equivalent-sized plasma sets.
  • Transport (yes, your car) is a big part of most households’ energy consumption. Buy the smallest, most economical vehicle you can get away with; ride your bike more; etc.

For all initiatives until from 2007 till June 2012, ReefHQ spent just under $300,000, saved 2.7 Gigawatt hours of electricity, reduced peak electricity demand by 110kw and avoided putting 2472 tonnes of CO2 into the atmosphere; and the return on investment was $460,000.

What we can achieve at home depends a lot on individual circumstances but a 20% benefit should be within easy reach of most of us and some of us will manage 50%.

Why should we bother? Two good reasons, one selfish and one not:

  • $500 – $2500 per year in our pockets.
  • If we can’t do something about climate change, the reef is doomed and we might as well close Reef HQ.
tank and panels on colourbond roof
Typical rooftop solar hot water system


(1) This article was written for a Townsville audience. Readers in cooler climates may need to think “heating” where I say “air-conditioning” but the same principle applies in reverse: lowering your heating system thermostat by a degree saves 10% of running costs.

(2) During preparation of this article, Sascha emailed me to add:

I recently replaced the last remaining 50watt dichroic lamps in our kitchen (I know… I should have done it ages ago). It was a bit hard to part with the cash as I bought high quality 10w LED lamps, which cost $350 for 10 lamps (ouch!). This change is saving me $260/year in energy costs, so the payback time is about 1.5yrs. The new 10w lamps are a bit bright so I probably could have got away with a lower wattage which would saved more and there are cheaper brands (however beware the really cheap brands), so you could easily achieve a payback time of one year. So you really are crazy not to change out your dichroic lamps, especially in high use areas (our kitchen lights are on about 7 hours per day).

(3) A good reference site for how much your appliances cost you is http://www.energyrating.gov.au/

This article appeared in a slightly different form in Waves, newsletter of Reef HQ Volunteers’ Association, February 2013.