Wednesday September 20 2017
Update
It’s been a while since the last post on the blog. I’ve been busy – among other thing, finishing the house! Photos, final budget and more blog posts coming soon! I also wanted to wait until I had an electricity bill for a full quarter since the installation of rooftop solar to crunch the numbers before writing about it.
I had always planned to install solar panels on the roof of 60k House, although that plan didn’t extend to running conduit from the roof through the ceiling cavity to the switchboard (unlike the provision for future solar hot water). The building is orientated to maximise solar gain, including the sun hitting the roof. Solar panels produce most power when the sun is perpendicular, meaning the supposed ideal roof pitch is the same as your latitude – that would be 42 degrees for Flowerpot.
The government giveth…
Solar panels were always a ‘nice to have’ not a ‘must have’ – the budget didn’t originally extend that far. Then came along a government initiative called TEELS – the Tasmanian Energy Efficiency Loan Scheme. TEELS is a joint plan by the Tasmanian government, Aurora Energy and Westpac to provide interest-free finance (up to $10,000) for the purchase of energy efficient products for Tasmanian households.
… and taketh away
I received a quote in May from the guys at CGA Tas for the supply and installation of the system. This included a government rebate. Frustratingly Westpac didn’t approve me for the full amount – I know banks don’t like self-employed people or small houses. Four months later the price of the Sustainable Trading Credits had dropped from $37.00 each to $30.50 – a $300 difference.
Confined spaces
Unfortunately I wasn’t able to coordinate running the conduit for the solar panels while the cement sheet cladding was off and the wall opened up for the heat pump installation. That meant Tye, the installer from Harvest Energy, had the unenviable task of crawling through the restrictive trusses to feed the cable (I did offer to do it). It couldn’t have been that bad for Tye – I’m now designing a beach house for him on Bruny Island! I also got Greg the builder back for a couple of hours to fix the framing and cladding.
Pull my finger: Sheldon pulls the conduit from the ceiling cavity through the wall to the meter box
What a mess: getting the power cable from the meter box to the inverter
Open air
While Tye was having the time of his life crawling around in the ceiling cavity, Sheldon installed the rails that the panels would sit on. An isolator switch for the array was also installed on the roof.
No big bang: Sheldon installing the isolator switch
Made in Norway
The panels come from Norway and are apparently the ducks nuts (good). There are 10 panels in total, each generating up to 280 watts, making it a 2.8kW system. Once all of the preliminary work was complete the panel installation was straightforward: lift them up onto the roof; plug them in; screw them in place.
Easy does it: lifting the panels onto the roof
Screw fix: connecting the panels to the rails
Place mat: Tye maneuvering a panel into place
Neat as a pin: the inverter installed with the cables concealed behind the wall
Daily read
Each morning I receive an email showing how much power the system generated the previous day. The Sunny Portal website is user-friendly and clear, displaying in real time the current power being produced, the CO2 avoided for the day and the current weather, among other things. You can also view graphs showing daily, monthly or annual production levels.
Daily mail: every morning I receive an email displaying how much power was produced the previous day
TIP: Use power hungry devices (washing machine, etc) when the sun is shining – use the power you’re generating for free (or would otherwise be selling back to the retailer for pittance) instead of buying from the grid.
April: going alright halfway through autumn
Year to date: monthly power production, still with a week of April to go
Savings
The first Aurora Energy (electricity retailer) bill I received after the installation included a network charge of $188 to modify the meter box. The most recent power bill covered 95 days of power supply and solar panel operation. During that time (from December 19 – March 23) the solar panels produced 1,170 kWh – about twice as much power as I used. I sold this clean, green power, free from the sun, back to the retailer at a rate of 9 cents per kWh. I buy power from the retailer for 26 cents per kWh – plus there’s the daily supply charge. Still, after the books are balanced my power bill for the quarter is only $120. Of course it helps that the house is sustainable and it was summer, but the bill is nearly half the price for the same period from the year before. It’s a shame the graph at the bottom counts the power produced from the solar panels as power used…
Money talks: my actual power bill for the past quarter
Clean power
Even at the height of summer I wasn’t able to quite hit 2.8kW power production. This prompted me to give the ‘self-cleaning’ solar panels a helping hand. I can’t tell if it helped much, but the view was nice.
Clean, green power: cleaning the solar panels
Comedic relief
Watch Tom Gleeson ridicule the ridiculous business model of non-renewable power production:
https://www.youtube.com/watch?v=rEqIKAH2KjQ
* Language warning *
Costs: solar panels & roof interface kit – $5,137; installation – $1,250; sustainable trading credits + $1,403
[total out of pocket expense for supply and installation – $4,984]
Disclaimer: Any advice contained within this blog is of a general nature only and cannot be relied upon. Details provided are in good faith and relate specifically to this project. Any author will not be held responsible for advice or information presented.
Hi Andrew, Just found your site and looking at the building progress. Planning on a small build myself. We have solar in Qld and it pays to keep the solar panels clean. We got a 5 kW system 5 years ago and I graphed the kWhrs for each bill and after 24 months I was not generating the power. There was a noticeable drop off in the graph. Once I washed the panels the generation was up. Each year in spring I go up with the hose and pool brush (long handled brush) and scrub the surface in the late afternoon (just before sunset) just to keep the generation. I can watch the film of dust and grim and bird dropping come off.
Hi Jim, thanks for your comment. That’s encouraging to hear that cleaning the solar panels does make a difference. Mine were only recently installed so couldn’t tell if cleaning would help production. They are supposedly self-cleaning but a bit of water and a scrub with the brush certainly helps. Cheers!