Rezachek & Associates'
Energy & Environmental Resources

PHOTOVOLTAICS

PHOTOVOLTAICS - What Is It?

Photovoltaics (often simply called "PV") is a renewable energy technology that converts sunlight directly into electricity. Sunlight shining on specially treated cells or films produces direct-current electricity.

Advantages

Working photovoltaic systems are mechanically simple; there are no moving parts in PV cells so the cells need no maintenance other than periodic cleaning.
PV cells generate direct-current electricity which can be stored in batteries and used in a wide range of voltages depending on the configuration of the battery bank.
The production of electricity by the photovoltaic process is quiet and produces no carbon dioxide or other toxic fumes.
Use of photovoltaics as a renewable source of electricity will help reduce Hawaii's almost complete dependence on imported fossil fuels.
Photovoltaics allow the use of electric lights and other equipment in isolated areas where connections to utility power lines are expensive or not available.
Although most electric appliances operate on alternating current, an increasing number of appliances using direct current are now available. Where these are not practical, PV-generated direct current can be changed into alternating current by the use of devices called inverters.
The State of Hawaii offers a 35 percent tax credit for the purchase and installation of photovoltaic and other solar equipment.

Disadvantages

Photovoltaic-produced electricity is presently more expensive than power supplied by utilities.
Photovoltaic cells must have light to create electricity. Shade from clouds, trees or nearby buildings reduce the output from a PV system. Batteries must be used to store electricity for use during non-sunlight hours.
High-voltage direct-current electricity can pose safety hazards to inadequately trained home operators or utility personnel.
PV systems which are connected to utility lines must provide power which is compatible with that of the utility and may require special interconnection equipment.
Batteries need periodic maintenance and replacement.
Some of the materials used in PV production are toxic.

The Basic Process

Photovoltaics are solar cells that produce electricity directly from sunlight. The solar cells are made of thin layers of material, usually silicon. The layers, after treatment with special compounds, have either too many or too few electrons. When light strikes a sandwich of the different layers, electrons start flowing and an electric current results.

Use of Photovoltaics in Hawaii

A residence in Manoa Valley on Oahu is almost completely equipped with PV-powered appliances and lighting. Connections to the local utility lines provide backup power when needed.

The Mana O Kala Farm on the Island of Hawaii has cars, trucks, and other equipment operating on electricity generated primarily by solar panels. The Kipu Kai Ranch on Kauai uses PV systems to supply some of the power for electric fences, residential and farm buildings, and other equipment.

Although a complete count is not available, it is estimated that more than 500 private homes and farms in Hawaii are using PV systems for some or all of their electrical needs. In addition, a number of remote communication systems and scientific monitoring equipment are powered by photovoltaics.

A 20-kW (nominal) photovoltaic demonstration project is operating at Kihei, Maui, as a satellite project of the national Photovoltaics for Utility-Scale Applications (PVUSA) program. This program is sponsored by the U.S. Department of Energy (USDOE), California Energy Commission, Maui Electric Company, state Department of Business, Economic Development, and Tourism (DBEDT), and others, to assess promising PV technologies. The project also transfers up-to-date information on photovoltaic technology to government agencies, the PV industry and U.S. utility companies.

A PV system installed by the state at a public boat-ramp at Moanalua Bay on Oahu provides night-time lighting at this facility. A 148-panel PV system was installed by the state in 1984 to provide electric power for lighting and office equipment in the Hawaii Institute of Marine Biology on Coconut Island in Kaneohe Bay. The system operated for more than two years as a demonstration project, and part of the PV array may be used for a Molokai water pumping and aeration project.

A PV-powered car, the Mana La, was constructed on the Island of Hawaii by Paul Mitchell Systems during 1987-88. The car, said to be capable of achieving 137 kilometers per hour (kph) at top speed, was entered in the 1988 World Solar Challenge, a 3,000-kilometer (km) race from Darwin to Adelaide, Australia.

PV-powered vehicles were designed, built and operated by students at Naalehu Intermediate School on the Island of Hawaii, Roosevelt High School on Oahu, and Maui High School. The three vehicles were entered in the Kaahele La (Tour of the Sun) Interscholastic Photovoltaic-Powered Vehicle Competition sponsored in 1988-89 by DBEDT and the state Department of Education (DOE). The Naalehu entry won the local competition and was exhibited at the Indianapolis Motor Speedway in 1989 as part of the Energy Program Managers' National Conference. The Kaahele La program was voted the Best Energy Education Promotion program in the nation at the Conference. This project was the first of its kind in the United States at the intermediate/high school level.

In 1989-1990 PV-powered vehicles were built by students at Farrington, Pearl City and Roosevelt high schools on Oahu, and Hawaii Preparatory Academy, Konawaena High School, and Naalehu Intermediate School on the Island of Hawaii. The six vehicles participated in the 1989-1990 Kaahele La competition. The winning car and team from Konawaena High School competed in and finished 18th of 36 teams in the 1990 World Solar Challenge race in Australia.

In the summer of 1993 a team of Konawaena High School students drove a PV-powered car 5,600 km across the U.S. mainland in 41 days, setting a new record. The vehicle, Spirit of Aloha, was designed and built by the students and had its origins in DBEDT's 1990 Kaahele La interscholastic solar car competition.

"The Sun Car of Kauai," Kaa La O Kauai, was a project started in 1992 by students at Kauai Community College. With funds from DBEDT, USDOE, Kauai County, and corporate and community donations, a team of students and teachers designed and built a tear-drop shaped, carbon fiber vehicle covered with about 800 PV cells. The single-seat vehicle had a titanium frame, 7 batteries, an 6-kW electric motor, and a maximum speed of about 89 kph.

In June 1993 Kaa La O Kauai took 9th place in Sunrayce '93, a 1,800-km, 6-day solar car competition from Arlington, Texas, to Minneapolis, Minnesota. Kaa La O Kauai also participated in Sunrayce '95, a 2,000-km race from Indianapolis, Indiana, to Golden, Colorado. It took 15th place overall, and received awards for Team Work, Most Improved Team, and Sportsmanship.

In 1992-93 and the next two succeeding school years, DBEDT and DOE sponsored the Mini-solar Vehicle Project, which provided Hawaii public intermediate and high school students the opportunity to design, build and demonstrate PV-powered, remote-controlled model cars less than 1.27 meters (m) long. The projects culminated in a demonstration meet held in April of each year in Honolulu. At the meet the vehicles of each school team were tested in dynamometer, wind tunnel, speed, road, trailer pull, and ramp trials. Hundreds of students participated and gained first-hand knowledge of solar technology while working collaboratively with their peers and a variety of experts.

A photovoltaic design component was added to the project in 1994-95, which was an option to construct a functional PV-powered prototype device. The prototypes and a mini-solar vehicle demonstration were presented at the First World Conference on Photovoltaic Energy Conversion (WCPEC), which was held at the Hilton Waikoloa Village in December 1994. Some of the many devices submitted included PV-powered hydrolysis, pumped hydroelectric generator, thermoelectric air conditioner, hydroponic system, smart window, desalinization, rotisserie, electronic learning center, catamaran, and radio. Some of these devices and others were exhibited at the DBEDT/DOE mini-solar vehicle demonstration meet in Honolulu in April 1995.

Hawaii is one of a number of states that have formed a national collaborative to support the Photovoltaics for Utilities program. The major focus of the program is to catalyze the efforts of key players from the utility, regulatory, PV industry, government, and consumer communities to stimulate greater near-term use of PV in the utility market for both grid-connected and stand-alone systems. The Hawaii collaborative meets quarterly and was instrumental in obtaining a grant from Sandia National Laboratory to fund PV startup and educational activities for Hawaii Electric Light Company. The Hawaii collaborative also obtained technical assistance to support a Pacific Island Photovoltaics Applications workshop held in conjunction with the WCPEC.

Most of information contained in this summary was excerpted from a Fact Sheet prepared by the staff of the Energy Division of the State of Hawaii-Department of Business, Economic Development, and Tourism (DBEDT) and published with funding from the U.S. Department of Energy, Grant No. DE-FG49-94R900023. This information does not necessarily reflect the views of the State of Hawaii, the United States Government, or any agency thereof.