ELM MicroGrid Projects
Eastern Caribbean Central Bank
LOCATION:Basseterre, St Kitts
This project has been awarded the 2023 Carribean Renewable Energy Forum's (CREF) Microgrid Project of the Year Industry Award.
The project scope involved the engineering and construction of two phases of PV carports and installation of two battery plants to minimize the grid export of electricity.
The definition of “net zero” is not strictly defined in the industry. In this case, “net zero” means the ECCB campus will net out to zero consumed grid electricity over time. Sometimes the campus will export energy and sometimes energy is imported. But over time that balance is zero.
We aren’t there yet. There is still energy efficiency work to be done, and possibly more solar energy on the roofs of some of the buildings. The energy efficiency work started with a walk-through ASHRAE Level-1 energy assessment. That led to lighting upgrades and various other improvements in their energy performance. Stay tuned for ECCB achieving that net-zero goal.
Solar carports are an excellent option for the Caribbean region. Land space often is in short supply, shading for parked cars is a big benefit for the drivers.
How about the two big challenges for the Caribbean: hurricanes and corrosion. The carports keep the solar arrays off the ground more than 12 feet. That reduces the likelihood of damage from wind-blown debris during a hurricane.
The site is less than a mile from the open ocean. The structures and all components are engineered for a 180-mph wind speed. The solar modules are rated to exceed the 180-mph design wind with repeated cyclical loading. Additionally, the steel structures are heavily hot-dip galvanized to control corrosion. The galvanizing coating is rated for a 30-year service life.
The ground conditions were another challenge. There usually is a good amount of topsoil in the mountainous Caribbean (as opposed to the Bahamas or low-lying islands with little topsoil). However, there was not a drill rig large enough to drill the necessary pier foundation to sufficient depth. So the engineering focused on spread footers, that are visible in the pictures below. These are massive rebar cages, 10’ on a side, filled with concrete, and buried under a layer of topsoil (so the parking lot grass can grow back quickly).
The schedule for the phases was demanding. Due to the risk posed by hurricanes, construction needs to be sequenced such that high-risk activities were not scheduled for the late summer months. Additionally, we used our hurricane preparedness process as part of the Safety Program to improve the successful outcomes regardless of weather.
The carports have LED lighting and security cameras installed underneath to improve safety and visibility.
Copy and photos by Marc Lapota, Azimuth Energy
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