The first ever utility-interactive (grid-tie) photovoltaic system is up and running at the Energy Division Office on Capital Hill.
Joseph C. Corella, general manager of Spectrum Electric Inc. and contractor for the project, said, “At long last, local residents, businesses and government facilities alike can now integrate renewable system technologies with their existing utility electrical systems for a cleaner and greener CNMI.”
Funded by the U.S. Department of Energy through the American Recovery Reinvestment Act funds, the project is the first formally recognized “grid-tie” system in the commonwealth, Corella said.
He said it was facilitated by a formal agreement with the Commonwealth Utilities Corp. wherein they reviewed and approved the equipment installed to allow it to be connected to the CUC grid.
“It’s exciting that CUC has finally adopted formal ‘net metering’ policies and has an ‘Interconnection Agreement’ available for residential, business, and government customers,” he said.
The contractor hopes the project opens doors for the public, both residential and business, to begin implementing and installing this “exciting” new technology.
The project required a local contractor to design, supply, deliver, install and commission a 2-kW wind turbine and solar panels with a capacity of no less than 2-kW for the Energy Division Office of the Department of Public Works on Capital Hill.
Corella said, “The work included but was not limited to 2-kW wind turbine — 33-foot tower — concrete turbine foundation, 2-kW solar panels, mounting hardware, inverter, metering, labor, material, components and accessories required to successfully commission the system in accordance with industry standards, National Electrical Code, local wind loading requirements, and codes and CUC net metering and grid-tie connection requirements.”
Spectrum Electric Inc. was issued the notice to proceed on Sept. 4 with the project’s completion expected in 190 days or due last March 13.
“This design-build project required the PV [photovoltaic] portion of the project to be designed and with a capacity of no less than 2-kW. After applying industry standard derating factors, it was determined that 13 each of 220-watt polycrystalline PV modules would be installed to facilitate the specified capacity. The modules were mounted on the flat concrete roof at a 5 degree tilt facing true South on high quality industry standard aluminum PV rack mounting system.”
The selected wind turbine — a Skystream 3.7 by Southwest Windpower — has a rated capacity of 2.4-kW depending on wind conditions.
Corella said Skystream 3.7 is a new generation residential wind generator that hooks up to the building’s electrical panel aimed at reducing electric bills.
“In a typical residential or small business application, the Skystream works in tandem with the electric utility power as the facility is served simultaneously by the Skystream and the local utility (CUC). If the wind speeds are below the required 8mph ‘cut-in speed,’ there will be no output from the generator and all of the needed power is purchased from CUC. As wind speeds increase, Skystream output increases and the amount of power purchased from CUC is proportionately decreased. When the Skystream produces more power than the facility needs, the meter spins backwards creating a credit that can be used later.”
He said everything is done automatically and does not require batteries.
Moreover, the system is secure even during a typhoon season as the Skystream 3.7 turbine is mounted on a “tiltable” 33-foot tower.
He said the process is simple and can be done in less than an hour and can be raised easily as soon as the weather has cleared.
Meanwhile, the photovoltaic part of the project required installation of 13 220-watt modules connected to an inverter called SMA Sunny Boy SB-3000-US inverter.
Corella said important data are provided via the SMA Web-Box mounted adjacent to the Sunny Boy inverter with information gathered by the SMA Sunny Sensor on the rack adjacent to the PV modules. An ambient temperature sensor is mounted under the roof overhang, with a PV module temperature sensor mounted to the back of one of the roof mounted PV modules.
“We are very pleased with the output of this system and how effortlessly it interconnects to the utility,” he said.
Variety inquired about the savings with the system. Corella said: “At 37 cents a kilowatt hour, we generated about 650 kw since we put it online. That is about $240 in savings since Feb. 1.”
From the Energy Division Office on Capital Hill, information on the photovoltaic system is fed to www.sunnyportal.com website that has information on hundreds of plants worldwide available to the public.
“The information is relayed from our location — at the Energy Office — via web connected electronic accessories we installed and is displayed on the inverter manufacturer’s website for ‘publicly available plants,’” Corella said.
The website, he said, offers interesting information as it logs all activity of the PV system; however, it does not log wind turbine activity.
