State and federal energy agencies have been expanding their financial and technical support for solar photovoltaic (PV) systems on public buildings. Is it time for your school to consider this option?

As costs for PV systems have come down from astronomical to merely super expensive, modular packaged units have become available for small commercial facilities. Programs pushing demo installations are supported by money from both the DOE and state agencies. Some have focused on adding small PV systems (typically 1 to 10 kW) on school rooftops as part of an educational effort that involves students, teachers, and community agencies. To find a list of which states are doing what, go to: www-solar.mck.ncsu.edu/sgs/sgsindex.htm or www.schoolsgoingsolar.org.

Some government incentives are also sky high, with California offering as much as $8.50 per installed peak watt. In New York, the New York State Energy Research and Development Authority offers $3 per watt, and Maryland gives $4 per watt for packaged 1 kW systems. By comparison, most incentives for energy efficiency equipment (e.g., lighting, motors, A/C) rarely exceed $.35 per saved watt.

Why does solar PV need so much money? Typical small units cost at least $6 per installed peak watt, with many systems having all-in costs closer to $10 per watt. To yield any realistic payback economics, programs must "buy down" the installation price to $2 per watt just to reach a 10-year payback (at a utility rate of $.10/kWh). That buy down may also include tax credits and other options, not all of which are appropriate to public schools.

So Why Bother?

Good question. Quick answer: This is a nice way to highlight clean energy options to both school administrators and "tomorrow's leaders" (i.e., students), and small PV systems don't cost much relative to a facility's annual equipment/energy budget. It's always been tough creating much of a buzz for new motors or A/C machinery hidden in mechanical rooms, while solar PV units are visible on rooftops, providing a futuristic cachet. If slapping a 2-kW system on the roof will get people thinking about how energy is used and supplied at a facility, many will believe it's a constructive form of education. For a listing of state incentives for renewable energy sources, go to www.dsireusa.org.

A Few Reality Checks

As anyone who has looked closely at on-site power generation (regardless of its type) knows, doing so often entails irritating issues such as interconnection standards, metering, inspections, etc. One such issue is "net metering," which allows power from a PV system to be fed back into a utility's distribution system through a customer's meter. While this option may maximize the dollar value of PV-produced power, it either does not exist in some states, or is restricted to residential electric accounts.

For a good overview of some of technical items related to solar PV, go to the Solar Electric Power Association's (SEPA) webpage at: http://64.243.182.248/includes/interconnection%20experiences.pdf. It is part of SEPA's Interconnection Handbook, all of which may be found at: www.solarelectricpower.org/interconnection/handbook.cfm.

But Will it Work on My Roof?

If not significantly shaded by other buildings, trees, or terrain, solar PV panels can produce power even in Canada. The real questions are: How much energy (i.e., kWh) will it produce each year, and what is the value of that saved energy? Depending on latitude, most of us will obtain between 1,000 and 2,500 full-output hours of power per year (more if you're deep in the Sunbelt or desert areas). That means a 2-kW system could provide (for example) 3,500 kWh/ year. At a U.S. average power cost of $.08/kWh, that has a value of $280 a year for a system that (without incentives) would cost $15,000 to $20,000 to install. If you can get a grant for $3 a watt, the price drops to between $9,000 and $11,000. You do the math. Most installations are happening where average power costs exceed $.10/kWh and incentives are $3 (or more) a watt.

No Dearth of Enthusiasm or Information

Many programs exist to promote solar PV, such as the DOE's Million Solar Roofs program (www.millionsolarroofs.com), for example. Programs focusing on elementary and high schools are featured at http://irecusa.org/schools (which has many good links). Distributors of solar PV packages (i.e., panels, inverters, etc.) have taken the lead in this area, among them Astropower (www.astropower.com) and SunWize Technologies (www.sunwize.com). One of the better overall information resources is: www.nyserda.org/energyresources/photovoltaics.html. While focused on New York facilities, a great deal of well-organized information is provided.ES