Battery key to island’s hybrid system

SMA's Sint Eustatius hybrid solar, battery and diesel plant.

SMA has commissioned a hybrid solar, battery and diesel plant to reduce fossil fuel consumption on the Caribbean island of Sint Eustatius.


By Jason Deign

Inverter maker SMA Solar Technology yesterday confirmed commissioning of a hybrid battery, PV and diesel system covering the electricity needs of a small Caribbean island.

The system will allow the 21km2, 3,500-population island of Sint Eustatius, in the Caribbean Netherlands, to cut its fossil-fuel consumption by 30%, equivalent to 800,000 litres of diesel and 2,200 tons of CO2 a year.

The hybrid system includes a 1.9MW solar plant, which can cover more than 23% of the island’s 13.5GWh annual electricity demand, plus 1MW of battery storage.

Diesel genset integration is through SMA’s Fuel Save Controller 2.0 software. SMA also supplied a Sunny Central Storage 1000 battery inverter and a Medium Voltage Power Station 1000.

This “enables a measured solar fraction of up to 88% during sunshine hours and supports the grid with stability functions such as frequency regulation, ramp-rate control for PV and optimisation of diesel genset operation,” SMA said.

Local meteorological conditions

Storage an important part of the project because of local meteorological conditions, said Volker Wachenfeld, executive vice president of SMA’s off-grid and storage business unit.

“Rapid movement of clouds in this region, in particular, leads to extreme fluctuations in solar power generation which constrains the integration of large-scale photovoltaics into diesel-based grids,” he said.

“That’s why using large-scale storage systems is meaningful for this application as they minimise the impact of fluctuating energy sources on diesel generators.”

The project also includes a service contract and a customised PV hybrid monitoring system engineered and commissioned by SMA Sunbelt Energy, an SMA subsidiary.

Until March Sint Estatius, which is known by locals as ‘Statia’, was entirely dependent on diesel generation. The Dutch Ministry of Economic Affairs funded the island’s move towards renewables.

Fossil fuel reduction

“We were looking for fossil fuel reduction and at the same time for a solution with both very low maintenance and also stand-alone operation,” said Fred Cuvalay, CEO of the Statia Utility Company, in press materials.

“SMA provided a hybrid system solution exactly tailored to our needs, which is extremely user-friendly.”

The project is said to be the first of its kind in the Caribbean region and “will likely serve as an example of what’s possible to neighbouring islands,” according to SMA.

Sint Estatius’ status as a burgeoning Caribbean renewable energy leader is somewhat ironic considering the island’s largest private employer is Statia Terminals, an oil terminal firm belonging to US pipeline operator NuStar Energy.

However, SMA is not the only company that thinks the Statia hybrid energy model could have applications elsewhere.

Off-grid hybrid plant

Earlier this month the Spanish wind turbine maker Gamesa unveiled a prototype 2MW off-grid hybrid plant design incorporating solar, wind, diesel and battery power.

“Rural areas, islands and other remote corners of the planet stand to benefit from these off-grid solutions which can generate cheaper and cleaner power,” said Gamesa chairman Ignacio Martín in a press statement.

The company, which in 2007 installed a wind-diesel hybrid in the Galapagos Islands, expects to sell up to 1.2GW of off-grid systems “in the coming years,” said David Mesonero, director of business development.

Gamesa told Greentech Media it was “actively marketing the solution, and is analysing dozens of projects in off-grid areas, mostly in Asia-Pacific, Africa and Latin America.”

Interest in hybrid systems combining renewables with storage and diesel has been alive for well over a decade.

Solar, diesel and battery hybrids

In 2006, for example, a study found that solar, diesel and battery hybrids were a viable alternative to grid extensions in Cameroon, Central Africa.

“Results show that there is a possibility to increase the access rate to electricity in the far north province without recourse to grid extension[,] more thermal plants or more independent diesel plants supplying remote areas,” it said.

More recently, the MIT Technology Review cited military equipment provider Earl Energy as saying that hybrid power systems using batteries and diesel “should cut by 50 to 70% the amount of fuel needed to generate electricity.”

Earl Energy was commercialising hybrid solar, battery and diesel systems for “over USD$100,000,” said to be comparable to the top-end price for a similarly sized genset.

And that was in 2011. Given recent strides in energy storage performance and cost reduction, it is likely the case for hybrid systems is much better now than it has been in the past.

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