Solar farms getting smaller, cheaper and smarter to overcome grid hurdles | RenewEconomy

Solar farms getting smaller, cheaper and smarter to overcome grid hurdles

Kanowna solar farm near Moree believed to be first to use both DC optimisers and centralised DC-coupled inverters to cater for battery storage and get around network connection hurdles.


At just 9MW, the Kanowna solar farm near Moree will not by any scope of imagination be the biggest solar farm in Australia. But it will likely be among the “smartest” solar farms in the country because of actions its developers are taking to deal with connection challenges and in preparation for battery storage.

The Kanowna solar farm is being built about 95km west of Moree in northern NSW, by the same people who delivered the Chillamurra and Dunblane solar farms over the past 18 months.

According to project manager Emma Mailler, the “cutting edge” nature of the technology is the use of both DC optimisers and DC coupled battery architecture for central inverters.

It is believed to be the first solar farm in Australia to embrace both technologies, a move partially driven by the connection hurdles and limitations being thrown at solar plants by network operators.

The use of the DC optimisers and the DC coupling for central inverters means that the solar farm can get by the restrictions being imposed by network operators, and both maximise the output of the solar farm and the battery storage, which can then be sent to the grid at times of peak demand or in the evening.

“Teams like ours can be more nimble, move more quickly and are more able to deploy cutting-edge developments like DC optimisation and DC coupled battery storage at utility-scale than larger projects,” Mailler says.

The Mailler team has already proven to be innovative through the use of the Belectric PEG framing technology, that uses less space and is quick to install, and says it has done its work without support from ARENA, the CEFC, or government off-take agreements.

The Kanowna solar farm, which will begin construction shortly and be complete in April, will operate as a “merchant” facility, selling its output into the grid, with a decision on battery storage to be made within a year.

“We work with private equity sourced from individuals who are committed to seeing progress on decarbonisation of our economy while achieving a healthy return on investment,” Mailler says.

“All our analysis, design and construction is carried out by entirely Australian enterprises. We carefully analysed performance differences between the DC optimised Chillamurra plant and other plants to confirm that DC optimisation was the right decision for Kanowna.”

The project will use 27,648 Seraphim PV modules all equipped with Maxim DC optimisers, which eliminate module mismatch loss and reduce hotspots, thereby minimising the rate of degradation. DC optimisers eliminate the usual impact of a weak module on a string, which in turn helps lower O&M costs. DC optimisers also permit longer strings, reducing construction costs.

DC coupling battery with solar means no changes to the AC front end when batteries are added, dramatically simplifying the grid connection process for storage.

“In Australia we are increasingly running into grid constraints that limit the size of the AC connections and short-circuit ratio problems that limit total inverter capacity at any given connection point,” Mailler says.

“We are also seeing problems with interference with load control frequency injection systems (i.e. ripple control) and fewer inverters helps here as well. DC coupling batteries (where the battery and the PV share the same inverter) is a very effective way to maximise the size of a solar plant in the face of these local grid challenges.

“The DC-coupled strategy stabilises solar output (in the event of passing cloud) and more generally resolves intermittency of renewables.”

Meralli Projects has been contracted to build the Kanowna Solar Farm. Meralli’s previous projects include Chillamurra and Dunblane. The solar farm will be owned by Kanowna Solar Pty Ltd, a special purpose vehicle established for the project and funded by private investors.

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