Episode 9 – Battery storage – adding a second Tesla PowerWall

2021 – Battery options modelling

In September 2020 we installed our first battery at Sturt Apartments, Christie Walk. You can read the story of our modelling, battery choices and lessons learned in Episode 7 – Battery storage – Tesla PowerWall 2

Everything had gone to plan with the installation of the battery; performance was as expected. The savings generated by our PV upgrade and the battery were flowing into our Green Fund, enabling us to begin planning for the installation of our second battery.

Our modelling indicated that our 21kW PVs were generating enough power to usefully support up to about 55kWh of battery storage, corresponding to 4 x Tesla PowerWall 2 batteries. In cost-benefit terms, a sweet-spot would be with 2 batteries. In the depths of winter in July – on many days – we’d still generate enough spare power to fully charge the batteries for use after sundown.

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Episode 4 – Major PV upgrade

Adventures with an environment-conscious inner-urban community

2019

For years we’d been tossing around options for increasing our solar performance without losing our high feed-in tariff (56c/kWh) for the 4.8kW PVs that were installed when the Christie Walk community built the Sturt Apartments in 2006.

But by 2019 it became clear that preserving the high feed-in tariff was a false economy. We’d be better off financially and environmentally if we replaced the PVs and inverters with a high performance 21kW system.

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Episode 3 – Evacuated tube solar hot water boosters

Adventures with an environment-conscious inner-urban community

May 2018

We started investigating the retrofit option for our hot water system: installing solar collectors as boosters to our existing heat pump hot water. One company stood out as a solid option: RunOnSun, based in the Northern Rivers region of NSW. Their website wouldn’t win a Webby Award for design, but the content is comprehensive and very educational. MD Andrew Butterworth has spent more than a decade applying Sydney University research on evacuated tube solar hot water and finessing it for efficiency and robust performance. The fixings supplied by RunOnSun are robust too; more than adequate to secure the system in cyclone conditions.

We decided to split the retrofit project into two stages. Stage 1 – 60 evacuated solar collector tubes – would be evaluated before moving onto Stage 2 – an additional 48 evacuated tubes.

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Episode 1 – In hot water again

Adventures with an environment-conscious inner-urban community

April 2016

Our apartment building (Sturt Apartments at Christie Walk) was nearly ten years old. It was time to start thinking about sustainability upgrades to reduce our carbon footprint.

Lighting was an easy place to start.

We worked with Adelaide lighting maintenance specialists Globebusters, who replaced unreliable CFL lights in our atrium stairwell and entranceway with long-life LED oyster lights and floodlights. In the courtyard, twin LED sensor floodlights replaced the old energy-hungry incandescent lights.

May 2016

Hot water; one of life’s great privileges. But our little luxury comes at a cost for us, and a carbon-cost for our warming planet. It’s a particular issue in our 4-level block of 13 apartments.

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Eco-city dreaming comes true

The facilitator asked us to do some dream-work.  That’s normally not so hard, but there we were, standing in an awkward-shaped T-allotment strewn with bits of broken glass and featuring some derelict out-buildings.  The site had previously been a city recycling depot and in a way one of our goals was to continue that recycling heritage.  We were asked to dream of what the features would be for our ideal sustainable-living community on the site. 

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