The diesel generators can be switched off completely during the day. This is unnoticed by electricity consumers but has huge benefits for the electric utility company and the region – and a pioneer for more diesel-free zones worldwide.
Anke Baars | SMA Solar Technology AG
The diesel generators have fallen silent. No longer is the idyllic island of St. Eustatius tarnished by their drone and black diesel soot. And gone, too, is the need to buy expensive diesel fuel. In November 2017, this Caribbean island – a “special municipality” of the Netherlands – became that little bit more special thanks to the launch of a diesel-free daytime electricity supply.
“The most exciting and certainly the most emotional moment of the project was when we shut down the diesel generators,” said SMA project engineer Hamed Sadri, visibly moved by this memory. After all, this is exactly the moment that he and his international team had spent the preceding two-and-a-half years tirelessly working toward. “The best thing was the sudden silence that descended as the generators were turned off. The light didn’t even flicker as the job of supplying electricity was transferred to the hybrid system.”
Therefore, most of St. Eustatius’ 4,000 inhabitants will not have even noticed this emotional moment – and that is a good thing, because for them life will not really change. For the local electric utility company Statia Utility Company (Stuco), however, this moment represented a milestone: A clean energy supply that will save 1.7 million liters of diesel fuel each year. And, it will also save 4,500 metric tons of CO2 every year. Thanks to this new hybrid system, the little island of St. Eustatius has become a model for the entire Caribbean region.
Diesel-free in two expansion stages
The first expansion stage went into operation back in spring 2016 after just nine months: 1.89 MWp of solar power combined with 74 SMA Sunny Tripower 25000TL-30 inverters, the SMA Fuel Save Controller and the Sunny Central Storage 1000 helped to reduce the consumption of the diesel generators by as much as 800,000 liters of fuel annually.
In the second expansion stage, the project partners doubled the solar output to 4.15 MW and increased the battery capacity to 5,900 kWh. The key component is the newly developed Sunny Central Storage 2200 battery inverter with grid-forming characteristics. This allows the diesel generators to be shut down fully automatically without compromising the stability of the frequency in the utility grid. The SMA Fuel Save Controller is responsible for real-time energy and power management and synchronizes diesel and battery operation intelligently and fully automatically. Within milliseconds, the system compensates for the PV array’s power fluctuations caused by, for example, the exceptionally fast-moving clouds in this region in particular.
This means that the diesel generators can be switched off completely during the day. This is unnoticed by electricity consumers but has huge benefits for the electric utility company and the region – and a pioneer for more diesel-free zones worldwide.
And talking of fast-moving clouds, the system thankfully withstood hurricanes Irma and Maria, which swept across the region in September 2017, leaving total devastation in their wake.
System profile: St. Eustatius solar hybrid system
The vision of reducing St. Eustatius’ dependence on fossil fuels was realized by the local electric utility company Statia Utility Company, the highly committed team of engineers from SMA, SMA Sunbelt Energy and the Dutch Ministry of Economic Affairs.
Customized hybrid system for a fossil-fuel-free electricity supply
- PV system: 4.15 MWp
- Storage capacity: 5.9 MWh
- PV inverters: 74 x Sunny Tripower 25000, 2 x Sunny Central 1000
- Batteries: Samsung lithium-ion NCM
- Battery inverters: 1 x Sunny Central Storage 1000, 2 x Sunny Central Storage 2200
- Solar energy fraction: 46%
- Open- and closed-loop control: SMA Fuel Save Controller
- Fuel savings: 5,500 liters daily, 1.8 million liters per year
- CO2 savings: 4,560 metric tons per year
- Project developer: SMA Sunbelt Energy GmbH
- Electric utility company: Statia Utility Company (STUCO)
- Financial support: Dutch Ministry of Economic Affairs
One integrated hybrid system with:
- Frequency (deviation 0.005 Hz)
- Voltage (deviation 0.4%)
- Spinning reserve provision
- Energy management
- Power management
- Automatic synchronization of “diesel on” and “diesel off” mode
- Robust design concept with built-in redundancy (communication loss, default behavior)
- Short circuit clearance within milliseconds
- Hot standby-uninterrupted power supply in case of diesel genset failure
- Over 100% solar power penetration during daytime
The heart of the project: the Sunny Central Storage 2200 battery inverter with grid-forming characteristics
About SMA Sunbelt Energy
SMA Sunbelt Energy GmbH is a 100% affiliated company of SMA Solar Technology AG headquartered in Germany. The company was founded in 2014 and focuses on off-grid, solar hybrid and battery-based projects. SMA Sunbelt offers SMA’s off-grid components to international clients and additional services including customized turnkey installations of PV-Diesel hybrid and battery based applications.
The content & opinions in this article are the author’s and do not necessarily represent the views of AltEnergyMag
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