Renewable Energy Makes the Grade: Photovoltaics are Perfect Match for K-12
March 29, 2010
By Alireza Hadian, Syska Hennessy Group
Ben Sedighi, Syska Hennessy Group
Appeared in American School and University
According to the U.S. Department of Energy (DOE), K -12 schools spend more than $8 billion annually on energy, making it their largest operating expense, second only to personnel. Coupled with the fact that harvesting solar energy takes place during the same hours as the school day and the opportunity to make a science lesson of it all, photovoltaics (PVs) can be an integral part of any K-12 energy initiative. For these reasons, the DOE created EnergySmart Schools, a program that challenges new schools to exceed code energy requirements by 50% and beating the energy code in existing schools by 30%.
Universities, on the other hand, have both energy-conscious students who demand their school be at the cutting edge of what’s “green” and faculty who may already be involved in researching and teaching emerging sustainable technologies. Incorporating PVs into the University syllabus is now more of a reality partly due to the American College & University Presidents’ Climate Commitment which calls for an 80% reduction in the emission of greenhouse gasses by mid-century at the latest through the development of a campus-wide sustainable action plan.
The benefits a PV system brings to a K-12 school district or university speak for themselves. Solar power not only reduces a district’s dependence on the utility grid by harvesting own energy naturally, but it also reduces pollutant emissions at the utility level as a result of decreased demand. According to the DOE, one 100Kw PV system diverts approximately 139,000 lbs. of CO2 annually.
Additionally, using a PV system will stabilize a school’s energy costs as fossil fuels become more scarce, increasing the school’s self-sufficiency. In warmer climates, relying on the grid during peak daytime hours can put an extra strain the budget, while PVs experience maximum output during these exact times when the sun is the strongest.
Arguably, though, the greatest benefit of a school installation is the educational opportunities the PV brings to the classroom and the community at large. A working system can be incorporated into engineering, environmental studies, business, architecture, design and natural resources, elementary science and technology curriculums as well as continuing adult and community education. In fact, much of what’s driving today’s K-12 schools to install PV systems is the opportunity to introduce renewable energies to their students and parents. School districts are approving funding for PV systems based on the unique educational opportunity they afford its student body.
While the initial price of a PV system can be a drawback, local, state and federal incentives can directly and significantly offset its cost (see sidebar). Like any other electronic system, the price of PVs has fallen drastically in the last few years, as a result of better technology and research on the development and manufacturing of 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 invest the financial capital of owning and operating a PV system is to purchase electricity through a Power Purchase Agreement (PPA). Here, a PAA or third-party company will design, install and maintain a PV either on your site or on theirs and sell you the electricity they generate. The independent company invests all the capital and the school just pays for the solar energy they use. However, the benefits of self-ownership are great, as it provides the school with a direct role in the design, execution and optimization of the PV system, including control over its operation and maintenance, without having to negotiate for the eventual system purchase, if necessary.
Fortunately, without a lot of expense, both new and existing schools can become PV-ready. The main challenge is to find a significant amount of uninterrupted square footage on the building’s roof for the PV panels. Ideally, areas to the West and South of a facility with little or no shading can provide the right environment for a PV system. While the challenge for the mechanical engineer will be to coordinate the placement of the HVAC and PV systems, the flat roof of a typical school building lends itself naturally to PV installation.
In new construction, building orientation and placement of the HVAC system and surrounding trees must be carefully planned. A new school provides the opportunity for an integrated PV system installation in which the PV modules are actually incorporated into the facility’s façade, canopy or roof. When PVs are integrated into the school’s roof, they also provide a shading element so that the sun’s heat isn’t absorbed into the building, reducing 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, as the school’s orientation to the sun is pre-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 still be achieved even without complete systems optimization.
Choosing and Maintaining the Right PV
As the cost of PV technology comes down and the popularity and applicability of the system rises, the amount of manufacturers and variety of systems will continue to grow. Within the range of current systems designs, there are a number of efficiency rates. Syska Hennessy Group recommends the highest efficiency module currently available which converts 100% solar radiation to 19.3% to electricity. While this seems small, the technology is growing and multiplying so much so that projected efficiency goals for 2012 are estimated at 30% efficiency.
Another significant component of the PV module is the inverter which converts DC (soar power) to AC power (electricity) to be used inside. Today’s most efficient inverters provide 96% efficiency, only loosing 4% heat during the conversion. Most of these high-efficiency systems also provide web-based capabilities so that a district’s central facilities office can monitor the PV system’s output on a real-time basis to print and compare their billing for utility used and electricity sold back to the grid. Performance software connected to a district-wide building automation system (BAS) can help optimize the PV array and track energy savings and systems performance.
The Case for One School District
When one large Southern California school district sought to fight its rising 15 cents/Kw hour utility bill, a PV system was the natural solution. Securing school board funding became possible only through the district’s pledge to use the system as a community-wide educational tool for students and parents. Using a set of comprehensive district-wide standards and baseline designs created by Syska Hennessy Group, a combination of five middle and high schools (including both new and existing facilities of different sizes), set out to install five PV systems in applications specific to each school.
The district employed both the Grid Tide and the Stand-Alone PV systems. The Grid Tide integrated system made of thin PV tiles (not panels) was installed on the roof of the new schools to function as a part of the roofing system itself. These PV tiles can be made to match the color of the building’s roofing tiles and are integrated into the roof, providing aesthetic appeal.
The Stand-Alone system created for the school district was designed for the sole purpose of educating its students. Located in one classroom within each school, between one and four PV modules use a DC-powered fan (a simple blade that rotates) to mirror the PV on the school’s roof, simulating real solar energy harvesting. This provides an opportunity for students, parents, administrators and board members to see how solar energy generation works first hand and how much energy it can really produce.
While the applications differ according to the specifications and existing conditions present at each school, the standards document created helps the district maintain uniformity across their PV systems, streamlining the installation, performance and maintenance of each.
There is no typical on-campus PV installation. The amount of sunlight and the availability of local, regional and federal incentives coupled with a school’s individual sustainability goals will shape each system. But, one thing remains uniform –the viability of PV technology for schools. From K-12 facilities to University campuses, PVs are now teaching both the theoretical and practical lessons that promise to drive sustainability beyond the classroom and into the next generation.
Ali Hadian, Senior Vice President, Principal, Special Projects Group Manager, Syska Hennessy Group, Los Angeles, brings over 25 years of experience as a consulting electrical engineer to his projects. He has been both the lead electrical engineer and project principal on numerous institutional, commercial and mixed-use projects. Ali is a proponent of photovoltaic system solutions and has experience integrating photovoltaic systems with base building electrical systems.
Ben Sedighi, PE, LEED AP, Syska Hennessy Group, Los Angeles, has over 24 years of experience in engineering and construction, working as a project manager in the educational, commercial, institutional and industrial markets. Sedighi has integrated multiple photovoltaic systems with base building electrical systems.
EnergySmart Program Sets the Bar for Today’s Schools
Created by the DOE, the EnergySmart Program is challenging today’s educational institutions to upgrade new schools to 50% better than current energy codes and improve existing schools by 30% within the next three years. Program goals include an annual savings of $2 billion, healthier schools for students, to familiarize parents, students and faculty with affordable, advanced energy-efficient technologies and practices and to play a role in reducing greenhouse gas emissions.
While PV systems can play a significant role, achieving the EnergySmart Program goals will require the combination of multiple energy-efficient strategies including daylighting, replacing incandescent bulbs with compact fluorescent bulbs, mechanical system upgrades, employing wind turbines and geothermal heat pumps and more. For more information on the program, visit www.energysmartschools.gov.
Incentives Fuel PV Installations