Adventures with an environment-conscious inner-urban community
2020
This was the crisis year for so many people – bushfires, COVID, job losses – and it also happened to be the year of our most adventurous emissions-reduction planning, carrying out 2 major projects a few months apart.
Stage 2 solar hot water boosters
The evacuated tube solar hot water boosters we had installed in 2018 were performing well, so it was time to build the second stage. We’d completed the design work in 2019 and had commenced the Development Application (DA) process with the City of Adelaide in September 2019. DA is required by Council if solar collectors are not mounted flat on the roof. After 9 weeks of back and forth, providing additional drawings and details, we finally received Planning Consent in mid-November.
We designed this Stage 2 set of 48 evacuated tubes to be installed at 45 degrees, optimised for winter. The 60 tubes in Stage 1 are at 30 degrees, for all-year-round performance.
By March we had checked final details and pricing with RunOnSun. When it seemed likely that State border closures due to COVID might impact delivery, we rushed through an order for the equipment. Then it was time to negotiate pricing and details with our installer, Jacks Plumbing & Gas. They’d done an excellent job installing Stage 1, so it was a no-brainer to have them back to do Stage 2.
Adding in the two additional banks of evacuated tubes went very smoothly and the system was operational on 21st May 2020.
Evacuated Tubes Stage 2 – installed cost
- Gross cost = $8,196
- less City of Adelaide subsidy $1,639
- Nett cost = $6,557
- emissions annual saving = 2.8tCO2-e
Lessons learnt along the way:
- The efficient low-wattage pump installed in Stage 1 – that circulates the hot water out of the evacuated tube manifolds into the hot water storage tanks – is easily able to handle pumping for the additional 48 tubes. We now have a total of 108 tubes installed.
- When available roof space is so limited, it is still possible to add solar collectors on some unlikely positions.
- Starting the process for Development Approval well in advance of the planned installation schedule greatly reduced stress in managing the project.
- It is possible to take significant load from an existing heat-pump hot water system by installing retrofit solar boosters, thereby extending the life of the heat-pumps and reducing demand on the electricity grid.
You can continue reading of our adventure with Episode 7 – Battery storage – Tesla Powerwall 2.
It’s part of our special series:
Aiming beyond NetZero at Christie Walk – Adventures with an environment-conscious inner-urban community.
Anthony
hi, would it be possible do know how you have your tubes plumbed ?
are they in series or parallel ?
what size pipe do you have running from your solar pump to the tubes
what sort of storeage tank do you have – does it have exchange coils in it
thanks
Tony
Urban Ecology
Hi Tony, Our 4 sets of tubes are plumbed in series. A single small Grundfos pump is enough to move the water through the manifolds. Flow and return loop is plumbed in 15mm lagged copper pipe, which is adequate because the water only needs to move slowly through the manifolds to achieve the heat energy transfer. We recently upgraded storage because 3 of our 4 Quantum heat pumps had reached end-of-life after 17 years of service. So we currently have – servicing 13 apartments plus a shared laundry – effectively 4 storage tanks. 2 are new Reclaim Energy heat pumps which preheat the cold water supply, an Apricus solar tank which receives the evacuated tube loop and Reclaim Energy hot water, and then does any needed top-up heating with its resistance coil, plus our one remaining Quantum tank that both heats and stores. So 4 storage tanks in all. Cheers, Brian