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Mar 1, 2010 12:00 PM, By Ali Hadian and Ben Sedighi
Photovoltaics can be a perfect energy match for the K-12 and university school day.
Solar power can reduce an education institution's dependence on the utility grid by harvesting energy naturally, and lower pollutant emissions by decreasing demand. According to the U.S. Department of Energy, one 100Kw photovoltaic (PV) system diverts about 139,000 pounds of carbon dioxide annually.
Using a PV system also will stabilize a school's energy costs as fossil fuels become more scarce and increase the institution's self-sufficiency. In warmer climates, relying on the grid during peak daytime hours can put an extra strain on the budget. PVs experience maximum output during these exact times when the sun is the strongest.
The greatest benefit of a solar installation at a school or university is the educational opportunity a PV system brings to the classroom and the community. A working system can be incorporated into curriculums for engineering, environmental studies, business, architecture, design and natural resources, elementary science and technology, as well as continuing adult and community education. In fact, much of what's driving schools to install PV systems is the opportunity to introduce renewable energies to students and parents. School districts are approving funding for PV systems based on the educational opportunity they afford its student body.
Get PV-ready
Although the initial price of a PV system can be a drawback, local, state and federal incentives can offset its cost (see sidebar, top right). The price of PVs has fallen drastically in the last few years as a result of better technology, and research on developing and manufacturing PVs. Ultimately, the amount of savings reaped from local solar production will depend on the amount of power produced on site together with the cost of utility purchases avoided.
Another option for schools that cannot afford to own and operate a PV system is to purchase electricity through a power purchase agreement (PPA). Through a PPA, a third-party company will design, install and maintain a PV either on the school site or elsewhere and sell the school the electricity it generates. The independent company invests all the capital, and the school pays for the solar energy it uses.
For education institutions that can afford the cost, self-ownership provides great benefits. It enables the school to have a direct role in the design, execution and optimization of a PV system, including control over its operation and maintenance.
New and existing schools can become PV-ready quickly. The main challenge is to find a significant amount of uninterrupted square footage on the building's roof for the PV panels. Areas to the west and south of a facility with little or no shading typically provide the best environment for a PV system. A mechanical engineer will coordinate the placement of HVAC and PV systems, but the flat roof of a typical school building lends itself naturally to PV installation.
In new construction, building orientation and placement of an HVAC system and surrounding trees must be planned carefully. At a new school, an integrated PV system can have PV modules incorporated into the facility's facade, canopy or roof. When PVs are integrated into a roof, they also provide a shading element so that the sun's heat isn't absorbed into the building. This reduces the demand on the HVAC system (and the energy and costs associated with it) while enhancing the life of the PV and the roof.
In existing buildings, the challenge is greater; the school's orientation to the sun already has been determined. If the building has an east/west orientation, it may be more difficult to get the PV system to the board. In a worst-case scenario, however, solar energy gains can be achieved even without complete system optimization.
Choosing the right PV
As the cost of PV technology comes down and the popularity and applicability of these systems rise, the number of manufacturers and variety of systems will continue to grow. Within the range of existing systems designs, there are a number of efficiency rates. The highest efficiency module now available converts 100 percent solar radiation to 19.3 percent electricity. Although this seems small, the technology is growing so quickly that projected efficiency goals for 2012 are estimated at 30 percent efficiency.
Another significant component of a PV module is the inverter, which converts DC (solar power) to AC power (electricity) to be used inside. Today's most efficient inverters provide 96 percent efficiency, losing only 4 percent heat during conversion. Most of these high-efficiency systems also have Web-based capabilities so that a district's central office can monitor a PV system's output on a real-time basis to print and compare their billing for energy used and electricity sold back to the grid. Performance software connected to a districtwide building automation system (BAS) can help optimize a PV array, and track energy savings and systems performance.
Incentives fuel PV installations
With few exceptions, most state, local and federal municipalities as well as local utilities offer grants or tax credit and rebate programs to subsidize as much as 60 percent of a photovoltaic installation. Although there are no school-specific grants, many Web-based resources provide information to schools planning a PV installation:
- Database of State Incentives for Renewables & Efficiency (DSIRE): www.dsireusa.org
- Collaborative for High-Performance Schools: www.chps.net
- Department of Energy for Renewable Energy: www.eere.energy.gov
- National Association of Energy Service Companies: www.naesco.org
- Environmental Protection Agency: www.epa.gov/enviroed/
- American College & University Presidents' Climate Commitment: www.presidentsclimatecommitment.org
- Read the "EnergySmart program sets the bar for today's schools" sidebar to learn about the DOE program.
- Read the "The case for one school district" web exclusive to find out how one school district fought its utility bill.
Hadian is senior vice president, principal and special projects group manager for Syska Hennessy Group, Los Angeles, and has more than 25 years of experience as a consulting electrical engineer. Sedighi, PE, LEED AP, is chief electrical engineer for the company and has more than 24 years of experience in engineering and construction, working as a project manager in several markets.
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