The solar system to take Flinders Island to 100% renewables


Flinders Island has always had a very high cost supply of energy. This is largely due to its reliance on diesel fuel as a source of power. Yet the price faced by consumers of electricity on the island is more in line with some of the rates being paid on the mainland, due to subsidies which keep it below the cost of production (which is around 50c/kWh).

I remember visiting the island as a child in the summer of 1988-89 and seeing for the first time the newly installed 55kW Enercon wind turbine, the first grid-scale (albeit a pretty small capacity) wind turbine. It was my first experience of renewable energy and from then on I was sold. It made intuitive sense even back then, and I could see that the world needed to be powered by renewables. Subsequently, in 1996, another Enercon wind turbine was installed, this time with a capacity of 88kW. Together the twin turbines produced about 1000 megawatt-hours of Flinders Island’s energy needs.

In a recent announcement Hydro Tasmania, supported by the Australian Renewable Energy Agency, said that it would take the island to 60% renewables using modular renewable and storage units that they will fly in from manufacturers based in Tasmania. This is a positive move, however in 2015 we can go much further. Instead of being 100% renewable for some of the time, Flinders Island can be 100% renewable all of the time.

For a 100% renewables-powered Flinders Island a distributed approach should be implemented to complement the ARENA/HydroTas “60% modular renewable solution” (low hanging fruit) project that is now being implemented, to be completed in 2016.

The distributed option would involve the following solar system being installed across farms and houses throughout the island:

1) Australian-made Selectronics SP Pro grid-limiting inverters (these control the output of solar panels fed into homes and the grid) rated to produce power at 7.5kW and above.

2) In conjunction with solar panel modules that have a combined capacity three times that of the inverters (see this article for why you would oversize the panel capacity relative to the inverter).  

3) The PV system’s power storage would then be sized appropriately with lithium-ion battery banks. It would be likely that the optimal size for each battery bank for the island to achieve zero emissions would be somewhere near the size of a Tesla Model S car battery bank of about 75-100 kilowatt-hours per supply premises. If this was planned for now it could be safely budgeted that the batteries would cost less than $200/kWh as prices head towards $US100/kWh thanks to the Tesla Gigafactory and other such efforts around the world.

The units would be remotely controlled by Hydro Tasmania, using an appropriate SCADA or equivalent system (i.e. via frequency control or remote access) with the electricity fed into the grid from the inverter being able to be curtailed at any time to help manage the supply and demand balance on the relatively small island grid. 

Some premises’ would not be suitable for such a type of system (e.g. rooftops too small) however this is not a problem as other systems that overproduce would take up the slack and kick in for those locations.  

Hydro Tasmania would also be able to remotely control the SP Pro inverters to regulate supply and fully understand, in real time, what’s happening across the island’s grid. Power factor correction and other ancillary services would be provided electronically giving the island better power quality than it has ever experienced.

Of course, SP Pro inverters – although the leader in terms of quality and functionality – may not be the only option. Chinese inverter companies are entering the hybrid grid/solar battery market and may offer a cheaper solution with sufficient functionality sometime in the future. They’re not there yet, but their progress is rapid.

Planning this future-proof system should commence now and should include the first 100 solar systems as part of the planning process. A quick assessment shows that 100 Selectronic SP Pro systems of 7.5kW each with 100kWh of storage and 23kW of solar installed on roofspace oriented north, west, east and south would contribute up-to an additional 2000MWh, which is well along the path to powering up a 100% renewable Flinders Island. The cost of rolling out 100 systems would be around $6-7 million. 

This would be money well spent, providing a prototype for other island grids and ultimately will help us understand how to scale up 100% renewable energy to much larger grids.

Matthew Wright holds a graduate diploma in engineering and is executive director of Zero Emissions Australia, technical director at Efficiency Matrix and resident columnist at Climate Spectator.

The Australian