SolarReserve may add 70MW solar farm to Port Augusta solar tower | RenewEconomy

SolarReserve may add 70MW solar farm to Port Augusta solar tower

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SolarReserve may add up to 70MW of solar PV to world-leading solar tower and storage project to boost output at peak times and reduce purchases from grid.

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US solar company SolarReserve has sought approval to add a 70MW solar PV farm to the world leading solar tower and molten salt storage facility proposed for Port Augusta in South Australia.

The plans for the additional solar PV are revealed in a development application to the South Australia Planning Commission, submitted in late April, and are designed to lower the costs for the project.

Aurora proposes a 150MW solar tower with eight hours of storage, the largest such facility in the world. The $750 million project is to get funding of $110 million from the federal government.

SolarReserve has also signed a contract with the South Australia government to provide electricity at no more than $78/MWh, after beating out competing tenders from gas plants. The new solar PV installation will help meet that target at lowest cost.

Analysts assumed that the solar tower’s storage facilities would allow it to sell electricity at peak times, helping to meet the low-priced contract with the government.

It would then buy electricity from the grid at other times when the price was low.

The addition of a solar PV facility reduces that arbitrage risk, as it locks in electricity supply – presumably at a lower price than $70/MWh, and can provide more electricity for the solar tower to store. And more that it can sell at peak times.

“Solar PV will supply the solar thermal power station’s electricity demand, which will enable the facility to supply more fully dispatchable elecrricity to the grid,” the submission says.

And it will “reduce the need to draw elecrricity from the grid for station power when the facility is not operating, and enhance the generation capacity of the project.”

A spokesman said a final decision on the solar PV installation had not yet been made, but the company wants to keep its options open.

The combination of solar towers with lower cost solar PV is not unsual. SolarReserve is using the same combination at its proposed facility in South Africa where the Lesedi and Jasper solar PV projects will combine with the Redstone 100MW solar tower.

The combination also features in solar thermal project proposals in Chile.

Solar PV has sidelined many solar thermal projects in the past 5 years because of its plunge in cost – up to 90 per cent by some estimates.

But it is now seen as a means to lower the cost of solar thermal, which is now more valued by grid operators because of its ability to store energy cheaply for long periods.

SolarReserve says the solar tower facility will need electricity to power heliostat trackers, pumps, lighting and associated equipment, including when the soalr thermal power station is not supply electricity to the grid.

SolarReserve expects to lock in financing by the middle of the year and began construction of the project in 2018, for completion in late 2020.

It will have been relieved to see the federal government has retained the $110 million funding promised – on several occasions now – which will likely be used as an equity investment in the project.

SolarReserve recently unveiled plans to jointly fund a transmission line with Oz Minerals, in a move that could open up new mining projects in the state’s north, with renewables and solar in particular as the likely major energy supply.


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  1. Jon 2 years ago

    Smart, export and self use as much PV generated power as possible and store the Solar Tower generated power for higher price windows.

    • david_fta 2 years ago

      While the sun shines, maximise heat accumulation in the thermal store by exporting from the PV farm, and draw down on accumulated heat in the evening and night.

  2. Jo 2 years ago

    A good plan!
    Using solar PV when the sun shines and putting as much energy as possible into the thermal storage for the hours when the sun is not shining is a saving on cost and extending the capacity of the power plant.

    • Rod 2 years ago

      I’ve decided to do something similar with my solar thermal hot water. Assuming I can source some used PV it should greatly reduce the grid boosting for not a great outlay.

      • Scottman 2 years ago

        I use a (home made) PV diverter on my solar thermal HWS, I know – many parts, reliant on the grid, BUT my setup up works so well I have had the controlled load disconnected also I don’t have the space for PV just for the HWS. There are pros & cons to any system.

        • Rod 2 years ago

          Good to hear it works that well. Yes the commercial diverters are very pricey.
          I’m on the high feed in tariff scheme and can’t change that system so this will be a stand alone array just for the HWS. I’m thinking I need 1.5kWp PV which should get 4 to 6 extra kWh into the tank on sunny days during Winter.
          I’m also out of roof space so these will go on an angled (for Winter) rack on a nearby shed.

          • solarguy 2 years ago

            I seem to remember hearing some where that you can get 1kw DC elements to replace the AC 3.6kw element. If you do the research then we will both know.

          • Rod 2 years ago

            I’ll look into it but TBH I am nervous about removing the old element from an oldish copper tank.
            Is there a benefit from going DC other than the purchase of the MPPT booster?

          • solarguy 2 years ago

            Another alternative would be to put in another collector (Evacuated Tube) 14 tubes should do it. If you don’t have any North space you can reverse pitch it on South roof with an angled frame, if not ground mount it or fix it to a North wall. The latter I did for a customer years ago. Cost about $1k.

            If you could get DC element you would go direct from PV array to element if the voltage matches element voltage window, so cheaper. I have no knowledge of these DC elements otherwise yet.

          • Rod 2 years ago

            Thanks. I should have said, it is a thermosyphon system so a second collector would have to go on the roof, I think.
            I’ll need a sparky anyway so I’ll run the two element options past them.

          • solarguy 2 years ago

            I’ll be amazed if the sparky knows. Thermosyphon, yes it will have to go on roof for sure, but as I said, reverse pitched on south if no room north. Just make sure it’s below tank inlet level and after the flat plate collectors in series i.e. last in direction of flow before going into tank.

          • Rod 2 years ago

            OK, thanks.

          • Alexander Hromas 2 years ago

            Be very careful with DC it can result in electrolysis and corrode your tank much safer to use an inverter and power the elements with AC. As long as you do not overload the inverter the rating of the heating elements is not that important. The electric energy gets converted to heat anyway. The best option is to use a heat pump running off the PV to heat the tank

  3. BushAxe 2 years ago

    I think most in the industry figured Aurora was going to supplement the CST to get the bid price down. The CST component will now be able to ramp more effectively in the peaks. The combined plant should be capable of 200MW in the summer.

  4. palmz 2 years ago

    This article has me asking the question.

    How much power dose a solar thermal plant need in it’s operation when it is not producing it using its stored heat ? (Just curious)

    • Susan Kraemer 2 years ago

      Total parasitic energy use is for example 10MW of the 110 MW Cresent Dunes plant (100 MW is net to the grid) and of Ivanpah Gross output is 392 MW and net available for generating MWhs to the grid after onsite parasitic use is 377 MW.

      These kinds of percentages of onsite power needs versus what they sell for delivery are typical of thermal power plants, gas, coal, geothermal etc.

    • BushAxe 2 years ago

      I think Solar Reserve are talking up to 15MW, so the max capacity is 150MW and a continuous rating of 135MW.

      • Susan Kraemer 2 years ago

        -for Aurora, you mean? Yeah, as a plant gets bigger it uses more parasitic energy in absolute megawatts.

  5. Robert Johnson 2 years ago

    Anyone run the numbers on PV + battery or pumped hydro relative to this tower?
    Interested to hear how it stacks relative to other technologies.
    150MW of PV is probably $200m. Take that from $750m project cost leaves $550m to buy pumped storage or batteries.

    • Peter F 2 years ago

      To provide 150 MW + 12 hours storage the solar thermal plant will average about 19 hours x 150 = 2800 MWh per day. In that region solar PV is about 28%+ CF so provide 2800 MWh you will need 425 MW of solar PV. If it is pumped hydro add about 25% to that so we now have an investment of $700 m in the generators. A 150 MW 12 hour pumped hydro plant is probably in the order of $200-250 m so system is $900 m vs $750 m

  6. SolarWombat 2 years ago

    Does anyone know why the expected cost as jumped from $650m when announced to $750m now?

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