Photovoltaic Systems Contribute to On-Site Renewable Energy

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The Brock Environmental Center will use photovoltaic (PV) systems as a part of its on-site renewable energy strategy. The system will convert sunlight into usable electricity and contribute to the facility being a net-zero energy building—targeting LEED Platinum and Living Building Challenge certifications.

photovoltaic system with solar arraysWhat is a photovoltaic system?

The word “photovoltaic” means light (“photo”) and voltage (“voltaic”). So a photovoltaic system uses photovoltaic cells to directly convert sunlight into electricity. The advantages to PV systems are that there are no moving parts, so it is easily expandable and modular. The system is also energy independent and environmentally compatible. They usually have long service lifetimes and require minimal maintenance. Although there are high initial costs, the economic value is realized almost immediately.

LEED and Living Building Challenge requirements

LEED provides 1-7 points for onsite renewable energy systems to offset 1-13% of building energy cost. LEED allows a building to take credit for technologies that generate electricity and heat from sun, wind, water flows and waste biomass. Therefore, the PV systems will contribute to on-site renewable energy for the Brock Environmental system by using energy from the sun.

Living Building Challenge’s Energy Petal requires that “one hundred percent of the project’s energy needs be supplied by on-site renewable energy on a net annual basis.” It further defines “renewable energy” to included photovoltaics, along with other systems. Further, the Materials Petal requires that the project account for its total carbon footprint from construction to completion; therefore, the construction team must use sustainable practices to support the mission of the Center.  

Using PV systems for construction

A 2.4-kilowatt (KW) mobile photovoltaic solar array is being used by Hourigan Construction and the subcontractors to provide power for construction of the facility and to run the on-site temporary offices. In addition, the solar array will power the motion sensor, perimeter security lighting and Ox-blue web-based, time lapse and video camera.

Meeting the net-zero energy requirement

In planning to meet the requirement of net-zero energy, the team had to estimate energy usage based on various weather patterns throughout the year. For solar power, the team took into account a typical year’s weather patterns related to the amount of “full sunlight” vs. “partial sunlight” based on cloud coverage during the year.

Further, the mechanical and electrical operating systems of the facility are predicted to consume more renewable energy (solar and wind resources) during the summer months and less during the winter months—resulting in net-zero consumption.

In order to achieve Living Building Challenge certification, the Brock Environmental Center will be required to take monthly readings and measurements for a period of 12 months after occupancy to verify that the building’s total energy usage is actually “net-zero”. In the case that the facility is not meeting the requirement, there will be future space available on the roof to add 90 panels to create the additional renewable energy. 

Photovoltaic system of the Brock Environmental Center

The actual PV system designed for the facility includes 162, 2’ x 4’ cells mounted to the top of the standing seam metal roofing. The PV system will be positioned to face the southern exposure of the sun in order to maximize as much direct sunlight as possible for the cells. The panels are located concentrically along the roofline of the building and centered between the east and west ends of the facility.

The panels will provide 39 KW of total power output, which equates to 60% of the facility’s total renewable energy sources (the other 40% being wind). Energy produced by the photovoltaic cells will either be immediately used by the facility operating systems or returned to the local power grid to be used by other local users, as there is no on-site “power storage” system.

In our next blog post, we will review wind powered renewable energy systems and how they work in conjunction with the photovoltaic systems.

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