Lady Elliot Island overview Lady Elliot Island is the southernmost cay of the , . The island lies 46 nautical miles (85 km; 53 mi) north-east of and covers an area of approximately 45 hectares (110 acres). It is part of the Capricorn and Bunker Group of islands and is owned by the Commonwealth of Australia. The island is home to a small eco resort and an airstrip, which is serviced daily by flights from Bundaberg, , and the Gold Coast.

Lady Elliot Island is located within the 'Green Zone' of the Great Barrier Reef Marine Park, which is the highest possible classification designated by the Great Barrier Reef Marine Park Authority. Marine National Park Green Zones protect the biodiversity within the Great Barrier Reef Marine Park by protecting important breeding and nursery areas such as seagrass beds, mangrove communities, deep-water shoals and reefs.[1] The island is particularly renowned for its scuba diving and snorkelling, as its location far offshore at the southern end of the Great Barrier Reef results in excellent water clarity. The Great Barrier Reef is one of the most important sea turtle habitats in the world, with Lady Elliot Island being a key part of that habitat. Every year between November and March the green and loggerhead turtles lumber up the same beach on which they were born more than 50 years ago. These turtles nest on Lady Elliot Island up to nine times in a season, laying between 80 and 120 eggs per clutch. About eight to twelve weeks later,[6] young hatchlings leave their nests and head towards the ocean (January to April).

Solar and Storage on the Island

Around 6 years ago Peter Libretto from Enertech on the Gold Coast solar became involved in trying to reduce the 680l of diesel consumption per day on generators which provided electricity to the island.

After the initial 6 x German manufactured SMA sunny island 5048 inverters were installed with a Multi cluster box 12, 2 x banks of German 3200Ah and a 21kW solar array were installed, it was proof that renewables set up correctly was the answer.

Over the following years we have added a further 70kW of solar with SMA Tripowers on a distributed network along with a further 3 x more sunny Islands and 2 x German BAE Tubular Gel 3600Ah battery banks.

As a result, we have reduced the daily diesel consumption from around 680l/day to around 90l/day, this has had a dramatic effect on the island, aside of the peaceful silence that comes with a diesel generator not running, the financial saving benefits have allowed the Resort to fund other projects such as upgrading the desalination plant, complete refurbishment of all of the guest accommodation, restaurant, swimming pool, revegetation programs, on site composter and dive shop.

Due to the resounding success of the solar and storage projects on Lady Elliot Island, they decided to keep up with ever rising energy demand by increasing the battery storage capacity.

However, this time due to long lead times with Gel battery manufacturers, we took the step of introducing a new technology, the Aquion salt water battery.

Aqueous Hybrid Ion (AHI™) chemistry is made from abundant, nontoxic materials; the batteries contain no heavy metals or toxic chemicals and are non-flammable and non- explosive, making them the cleanest and safest batteries on the market.

AHI chemistry is composed of a saltwater electrolyte, manganese oxide cathode, carbon titanium phosphate composite anode, and synthetic cotton separator. The battery utilizes non-corrosive intercalation reactions at the anode and cathode

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Exploded view of an Aquion Battery stack

The challenge that we faced was that although there had been great success with Aquion in America, no one had ever introduced this new completely different technology into an existing Lead Acid battery system. On top of this, we already had SMA SI5048’s of which are now discontinued in place of the new SMA Sunny Island 8.0H, so to summarise, new battery technology and new battery chargers into an existing lead acid discontinued inverter system.

With the Aquion batteries, they come in stacks rated at 48V, unlike the traditional lead acid cells of this size in 2 volts, therefore, with 36 x stacks rated at around 2Ah per stack, we had to parallel all of the stacks together in a combiner box which we designed and manufactured off the island. This box provided circuit protection for each stack and combined all of the positives and negatives on separate bus bars. Each stack passes through an electronic box which collects all of the data such as current, temperate etc and relays it to the system BMS, in turn this is sending the data to the new cluster of 3 x sunny Island 8.0H.

Once the mammoth task of wiring each stack, 3 x SMI boxes, combiner box and sunny islands had been completed, we had to completely reconnect the communication system within the multi cluster making the new SI8.0H’s the master cluster. As a result, the system was reconfigured and immediately connected to the site loads and existing lead acid banks, within 12 hours all 4 x battery banks were showing state of charge within 1% of each other and balancing the loads superbly.

After a week of testing and running, the anticipated generator run time now is expected to be under4 hours per day.

36 x stacks of Aquion salt water batteries alongside the German Gel lead Acid batteries

Combiner box, 3 x SMI stack monitors and the Battery Management system

3 x Sunny Island 8.0H’s