Learning About PV: The Myths of Solar Electricity
U.S. Department of Energy - Energy Efficiency and Renewable Energy
Solar Energy Technologies Program
Research progress continues, better positioning current and next-generation photovoltaic ( PV) technologies to meet future electricity needs. But these successes seem to spark some criticisms and questions. Some are warranted. Some are based on partial truths. And others are perpetuated from urban legends or myths about the technology.
Common among these criticisms and questions are the seven myths of solar electricity:
- Myth 1: Solar electricity cannot serve any significant fraction of U.S. or world electricity needs.
- Myth 2: Solar electricity can do everything — right now!
- Myth 3: Photovoltaics cannot significantly offset environmental emissions.
- Myth 4: Photovoltaics is a polluting industry.
- Myth 5: Photovoltaics is merely a cottage industry, appealing only to small niche markets.
- Myth 6: PV is too expensive and will never compete with "the big boys" of power generation. Besides, you can never get the energy out that it takes to produce the system.
- Myth 7: Nothing remains to be done. Essential R&D is complete, the product works — just close the laboratory doors and let industry fight it out.
Myth 1: Solar electricity cannot serve any significant fraction of U.S. or world electricity needs.
PV technology can meet electricity demand on any scale. The solar energy resource in a 100-mile-square area of Nevada could supply the United States with all its electricity (about 800 gigawatts) using modestly efficient (10%) commercial PV modules.
A more realistic scenario involves distributing these same PV systems throughout the 50 states. Currently available sites—such as vacant land, parking lots, and rooftops—could be used. The land requirement to produce 800 gigawatts would average out to be about 17 x 17 miles per state. Alternatively, PV systems built in the "brownfields"—the estimated 5 million acres of abandoned industrial sites in our nation's cities—could supply 90% of America's current electricity.
These hypothetical cases emphasize that PV is not "area-impaired" in delivering electricity. The critical point is that PV does not have to compete with baseload power. Its strength is in providing electricity when and where energy is most limited and most expensive. It does not simply replace some fraction of generation. Rather, it displaces the right portion of the load, shaving peak demand during periods when energy is most constrained and expensive.
In the long run, the U.S. PV Industry Roadmap does expect PV to provide a "significant fraction of U.S. electricity needs." This adds up to at least 15% of new added electricity capacity in 2020, and then 10 years later, at least 10% of the nation's total electricity (PDF 674 KB). Download Adobe Reader
Myth 2: Solar electricity can do everything — right now!
No way. Solar electricity will eventually become a major player in the world's energy portfolio. The industry just doesn't have the capacity to meet all demands right now. But assuming that the proper investments are made now and are sustained, the industry will become significant in the next few decades.
In 2000, for example, worldwide PV shipments grew by 37% from the previous year. In 2001, they grew by another 38%. Although this brought shipments to about 400 megawatts per year, it's hardly enough to meet the entire burden of U.S. or world electricity needs... yet.
Myth 3: Photovoltaics cannot significantly offset environmental emissions.
Around the Chesapeake Bay Foundation (CBF) Philip Merrill Environmental Center native plants enhance rainwater filtering, and need no fertilizers, pesticides or watering. The site plan was designed to leave mature native hardwoods standing. The building was designed to maximize energy efficiency and includes the following low energy features: natural ventilation when ever possible, extensive daylighting, solar hot water, 4 kW photovoltaic ( PV) system, geothermal wells, and structurally insulated panels (SIP).
- 16 kilograms of nitrogen oxides
- 9 kilograms of sulfur oxides
- 2,300 kilograms of carbon dioxide (CO2)
If the industry grows by the 25% per year as predicted (see U.S. PV Industry Roadmap (PDF 674 KB). PV in the United States will offset 10 million metric tons of CO2 per year by 2027 — equivalent to the annual increase emitted by U.S. fossil fuel electricity generation. This means that the emission rate will become negative thereafter as the PV contribution grows!
Myth 4: Photovoltaics is a polluting industry.
The PV industry is neither "squeaky clean" nor a major environmental, safety, or health problem. When it comes to emissions, PV's electricity-generating portion of the fuel cycle is the clear winner versus fossil fuel sources. However, semiconductor processing can involve the use of chemicals and toxic materials.
Some 80% of the current PV industry is silicon. Basically, it uses the same processing as the semiconductor industry, which is touted as being comparatively clean. It also has the same risk. There are various codes, controls, and regulations in place that oversee PV silicon industry operations, ensuring that it's relatively safe.
PV materials that incorporate heavy metals or toxic materials are continuously scrutinized to ensure safety. To date, the Environmental Protection Agency, Underwriters Laboratories, and others have conducted testing and investigations that indicate no problems. But the programs and companies involved remain vigilant and active in ensuring safety. Industry has made many improvements in areas such as:
- Safer etching
- Lead-free solders
- Automated handling and robotics
- Redundancy in ensuring critical operations
- Stringent training
Myth 5: Photovoltaics is merely a cottage industry, appealing only to small niche markets.
This 5- megawatt solar-cell production equipment at United Solar, built by Energy Conversion Devices (ECD), is dedicated exclusively to triple-junction cell production. ECD's goals under its 1998 PV Manufacturing R&D subcontract was to reduce module cost by 25% - 30% and increase manufacturing capacity by 60%.
This is a real business — one that has been growing by more than 35% per year over the past 2 years. In 2001, PV module shipments closed in on the 400- megawatt mark, representing a $2.5 to $3 billion market. The U.S.-based industry itself is now approaching $1 billion per year and providing 25,000 jobs. It's expected to grow to the $10-$15 billion level in the next 20 years, providing 300,000 jobs by 2025. This sustained growth exceeds that of the semiconductor industry.
A market shift has sparked the recent growth in the PV industry. It has shifted from almost completely remote, off-grid, and consumer products to nearly 60% grid-connected, distributed power. And these applications don't represent small niche markets. They represent the significant growth path for PV — the true distributed power source.
Myth 6: PV is too expensive and will never compete with "the big boys" of power generation. Besides, you can never get the energy out that it takes to produce the system.
The cost of producing PV modules, in constant dollars, has fallen from as much as $50 per peak watt in 1980 to as little as $3 per peak watt today. This causes PV electricity costs to drop 15¢-25¢ per kilowatt hour ( kWh), which is competitive in many applications.
In the California market, where state incentives and Net Metering are in place, PV electricity prices are dipping below 11¢/ kWh, on par with some utility-delivered power. Moreover, according to the U.S. PV Industry Roadmap, solar electricity will continue this trend and become competitive by 2010 for most domestic markets (PDF 674 KB). Download Adobe Reader
The energy payback period is also dropping rapidly. For example, it takes today's typical crystalline silicon module about 4 years to generate more energy than went into making the module in the first place. The next generation of silicon modules, which will employ a different grade of silicon and use thinner layers of semiconductor material, will have an energy payback of about 2 years. And thin-film modules will soon bring the payback down to one year or less. This means that these modules will produce "free" and clean energy for the remaining 29 years of their expected life.
Myth 7: Nothing remains to be done. Essential R&D is complete, the product works — just close the laboratory doors and let industry fight it out.
This thin-film photovoltaic material can be building integrated. This material can be fastened to roofing surfaces, such as standing seam metal (shown in the right photo) to produce electricity. The home in the foreground (right side) has building integrated PV.
As high-tech energy production, PV has immense potential to evolve, develop, and advance. Our current technologies still have substantial potential for improvement.
Research and development (R&D) in processing, process understanding, and manufacturing remains in its infancy. There is much important R&D still to be performed, not just on cells and modules, but also on balance-of-systems components and on systems themselves.
Many new and next-generation materials, devices, and physics are only concepts. Others are still to be discovered. Among these will be authentic breakthroughs that will boost PV to the next levels of performance. It is up to us to make and manage the investments to own these. Delays in making these investments will mean lost opportunities. First, it will take longer to bring this clean energy source into widespread use for us and our descendants. Also, there will be a loss of technology leadership and ownership.
Failing to take R&D leadership creates a pathway of diminished U.S. innovation, technology ownership, and energy ownership and control, as well as the loss of substantial economic benefits. Investing in PV R&D and clean solar electricity for our nation's future is good, sound business. And that's the truth.
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