The Caribbean island of Sint Eustatius has changed its power generation paradigms by reducing diesel consumption with a 1.89 MW solar PV and 1 MW/572 kWh Li-Ion battery energy storage system. THEnergy has performed a data analysis for the first year of operations. Large-scale hybrid systems are rather complex, and for island utilities it is difficult to fully assess the outcome of hybridizing their diesel power plants with solar power plants on fuel consumption. They typically rely on the calculations of the manufacturers or on rather costly third-party studies.

Lead image: PV-Battery Diesel Hybrid Plant on Sint Eustatius © SMA Sunbelt.

In the case of Sint Eustatius, the performance of the plants exceeds the forecasts. The share of solar energy on the island energy mix was higher than predicted for the first year of operations. Relative diesel savings were 3.4 percent higher than forecasted: diesel consumption was reduced by 62 l/MWh instead of 60 l/MWh. These additional savings are particularly remarkable, as solar irradiation during the year was 4.9 percent below average due to local weather conditions. Even the total savings in diesel were in line with those forecasted. This is also reflected in the slightly higher than expected performance ratio of the solar PV plant.

The analysis also shows positive findings for battery performance. While a degradation of 4 percent was expected, the actual degradation after the first year was 1 percent. It is realistic to assume that with normal weather conditions, and the extremely low degradation of the battery energy storage system, the future performance of the plant will be even better than during the first year.

The outstanding results of the new system are also the main reason for the island utility deciding to expand the plant in the near future by adding 2.25 MW of solar power, and 4.4 MW/5.2 MWh of battery energy storage. As Fred Cuvalay, CEO of Stuco explained: “We are fully convinced of SMA Sunbelt, which is particularly important, as in this next step we will switch off our diesel gensets during sunny days and will fully rely on renewables.”

Large PV-battery diesel hybrid plants are still relatively new. On islands in particular, the reliability of the supplier is a key success factor. Bad planning and technical issues may lead to huge consequential costs. This project will also be a signal to other islands of what can be achieved by integrating renewable energy.

View the analysis here for further information and detailed results.