(Updated with details from Neoen financial accounts).

French renewable energy and battery storage company Neoen says its wholly owned Tesla big battery next to the Hornsdale wind farm in South Australia is operating “superbly” and has maintained its unexpectedly high profits in the latest half year period.

The 100MW/129MWh Tesla big battery – officially known as the Hornsdale Power Reserve – opened in late 2017 after being built in less than 100 days (as promised by Tesla boss and co-founder Elon Musk) and requested by the then South Australia Labor government.

It remains the world’s biggest lithium-ion battery and has impressed not just network owners and grid operators with its overall performance, and and speed and versatility and ability to hold up the grid in the case of wider outages, but also the investment community with the scope of the financial returns delivered. It has also delivered more than $50 million in grid savings in its first year.

The earnings for its first six months of operations were revealed last year when Neoen filed a prospectus for a stock exchange listing, which said that the Tesla battery – which cost $91 million – earned $A13 million (EBITDA) in the first six months, including $A2 million from the South Australia contract and a further $A10.8 million from the sale of stored electricity from the Hornsdale battery.

Most of this market earnings came from the FCAS market, with the battery earning $A7.1 million from the sale of FCAS. For the whole year, the Tesla big battery delivered a profit of $22 million for Neoen.

Neoen released its results overnight and declares that storage earnings (EBITDA) steady at €6.7 million in the half, on revenue of €8.3 million and an operating profit from battery storage at €4.1 million, although the exchange rate may have disguised a slight increase in profits in Australian dollar terms.

In a presentation to analysts and a web-cast, Neoen indicated that the earnings (before interest, tax and depreciation) from the Australian battery operations, which includes the smaller 6MW/1.4MWh battery at the Degrussa copper mine in Western Australia, was unchanged from the previous six months. (See table above). The revenue and operating profits were slightly higher than the same period a year ago.

Profit increases also came from Neoen’s solar operations, thanks to financing of $A143 million in debt from its Dubbo, Parkes and Griffith solar farms that led to a near $A10 million accounting windfall from lower interest costs, but fell in wind farms, the result from shifting to highly profitable merchant sales (thanks to high wholesale prices), to long term fixed contracts, in this case for the ACT government.

Neoen CEO Xavier Barbaro said Neoen is expected to complete its second big battery at the 214MW Bulgana wind farm in Victoria later this year. This battery will be sized at 20MW/34MWh, and will help deliver 100 per cent renewable electricity to Nectar Farms and its proposed huge vegetable greenhouse.

Other projects in the pipeline include combined solar, wind and storage projects at Crystal Brook and the massive South Goyder project in South Australia, the Kentbrook wind and battery hub in a Victoria pine plantation, and the Kaban renewable energy and storage hub in north Queensland, which was shortlisted for a recent state government auction.

Battery storage currently accounts for seven per cent of Neoen’s earnings, with solar overtaking wind as the major contributor, and Australia remaining the biggest source of revenue for the company that has operations in Europe and the Americas.

“The Tesla big battery is still working superbly,” he told the webcast. Neoen is also about to compete a smaller 3MW/1.8MWh battery storage project as part of a 139MW cappella solar farm in Mexico, which will help it integrate into the grid and avoid added costs.

Neoen noted that it had been one of four wind farm operators that had been subject of court action from the Australian Energy Regulator arising from the state-wide blackout in South Australia in September, 2016. Neoen said AER was seeking an unspecified fine, but Neoen is contesting the issue and made no provisions in its account.