I was fortunate enough to visit an island off the New England coast to help out with the commissioning of a terrific off-grid solar electric system. Appledore Island is home to the Shoals Marine Laboratory (SML), run together by Cornell University and the University of New Hampshire. Students and staff live on the island seasonally, performing research in marine sciences. They collect their power from a combination of a wind turbine, solar panels, and a generator. Dave Ayer, from Ayer Electric, LLC in Portsmouth, NH is the lead installer on the project and installs renewable energy systems throughout the New England area.
The SML wind turbine is a Bergey 7.5kW Excel model on an 80-foot tower, capable of producing 7,500 watts at 28 mile per hour winds. Notice in the pictures that one of the three blades of the wind turbine is painted black. This causes the blades to be visible to birds when they are spinning. The ground around the turbine is constantly monitored, and it has never harmed a bird.
In addition to the wind turbine, they recently added 26.4 kilowatts of solar electricity, which together with the wind power, charges a 6,000Ah, 48V battery bank. The solar panels are installed on the building’s roof, as well as on two ground mounted solar panel arrays nearby. In case there is not enough wind or sun, two 27kW, 3-phase diesel generators are able to charge the batteries and provide extra power when needed. For example, the generator-charged batteries will run the compressor to charge diving tanks.
The Schneider Conext XW system consists of six Xantrex XW6048 Inverter / Chargers, configured as 3-phase 208V, with two inverters for each phase; one set as master and the other as slave. This way, when they have low loads, only three of the six inverters will turn on; one per phase. SML’s solar electric array feeds into six Xantrex XW 80A MPPT High Voltage Solar Charge Controllers. The Schneider XW system has two System Control Panels that monitor their system locally and provide displays in the solar room, as well as having a Schneider ComBox Communication Device which allows them to monitor and configure the system remotely via the web.
This renewable energy system, comprised of solar and wind electric systems, will enable the research lab to operate without using diesel most days, saving money as well as resources required to haul the diesel onto the island and greatly reducing the amount of diesel burned.