ECOLEAF: Understanding Solar Photovoltaics (PV) and Thin Films a Renewable Energy

ECOLEAF: Renewable Solar Energy (PV)

The photoelectric effect (which occurs when materials absorb light) was first identified by French Physicist Edmund Becquerel in 1839. By 1894, Charles Fritts, an American scientist, used the photoelectric effect to develop/invent the first working solar cell. It boasted an efficiency of a mere 1 to 2%. A full 60 years passed before enough sufficient electrical power could be generated from a solar cell to make the technology commercially viable.

In 1954, however, Bell Labs did this when they achieved a 4.5% efficiency. Six months later, they had achieved 6%. The first electrical grid supported by a photovoltaic (PV) system had a capacity of 0.5MW and was installed in 1993 in Kerman, California by Pacific Gas & Electric.

The largest PV installation in the U.S. is in Nevada. It has a capacity of 14MW. In contrast, Spain has a facility capable of producing 23MW.

PV power is currently separated into two groups based on the type of technology used to create it. Crystalline PV is more efficient, has a higher per-panel cost, and utilizes a smaller surface area footprint than Thin-Film PV. Thin-Film performs better in diffused light conditions (cloudy and overcast) but requires more surface area and a higher number of deployed panels for comparable net production efficiencies. It also entails higher total construction and installation expenses. The cost of installing these systems accounts for 73% for Crystalline modules and 55% for Thin-Film modules. The caveat: to reach a comparable efficiency, Thin-Film needs three times more land area than does Crystalline resulting in higher overall expenses.

Unlike concentrating photovoltaic panels (CPV) or other sun collectors (such as Solar Thermal Energy) that require direct sunlight to capture energy, PV does not. This means that no moving components are needed in PV systems to track the sun. This also means that PV can be rapidly deployed. Power reliability is an issue, as power varies from hour to hour on the sun’s availability.

Crystalline technology has traditionally been the main technology source for PV systems. However, due to the limited availability of silicon, Thin-Film PV is becoming a more promising alternative. Thin-Film has a lower manufacturing cost, does not require a frame (like a metallic picture frame) on each module for construction and the cost of the materials utilized to manufacture the panels is less.

In 2007, Thin-Film had an 8% share of the PV market. Other alternative PV technologies include GaAs, CIGS, and CdTe, all of which will impact efficiencies, supply and cost options for the future. Due to increased acceptance by consumers and businesses, reduced overall system costs, and large annual growths in supply and demand, PV represents a growing force in renewable free energy from the sun.

Global PV Energy Capacity in 2005: 9.3GW

US PV Energy Capacity in 2005: 2.8GW (30.1% of the World)

US Solar PV electricity consumption in 2005: 200 GWh

Average PV Efficiency: 23 to 25%

Overall costs for PV continue to drop. In 2004, a solar PV system cost $6,100 per KW ($0.182/kWh); in 2006 it dropped to an average of $4,000 per KW. It’s estimated that in 2010 the per-watt cost for a panel for Thin-Films will be $1. The per-watt cost for Crystalline will be $2. (These costs do not account for installation.) An important point to make about solar-based energy systems, however—whether PV, Solar Thermal, or CPV—is that they can only operate during daylight hours. By contrast, a coal plant can operate 24 hours a day…and a new coal plant costs only $2,500 per KW.

There are over 400 companies producing PV. In 2007, the leading manufacturers were Sharp of Japan, Q-Cells of Germany, and Suntech of China. With 3,862 MW, Germany was the largest installer of PV. Japan is in second place with 1,920 MW, the United States has 830 MW, and Spain has 655 MW.

Global PV Energy Capacity in 2007: 12.4 GW

In 2007, Germany had approximately 50% of the world market of PV. Germany’s PV installation continues to grow faster than the rest of the world due to a “feed-in” tariff program (the Renewable Energy Sources Act) that requires utility companies to purchase energy generated from PV installations at twice the rate paid by private households. The feed-in tariff is 49¢ per kWh. It is anticipated that the rate will decrease to keep pace with the drop in the cost of installed PV systems.

NOTE REGARDING CPV TECHNOLOGY: SolFocus has a different approach when it comes to PV: they are using mirrors and lenses to concentrate the sun’s rays by a factor of 500. Known as concentrating photovoltaic (CPV) [panels], the technology uses optics to focus the sunlight onto a high efficiency PV at 40% efficiency (four times more efficient than Thin-Film PV and more than twice as efficient as Crystalline PV) onto a small footprint (1/1000 the amount of PV in traditional systems). In 2008, SolFocus completed 500kW of a 3MW-installation for the Institute of Concentration Photovoltaic Systems (ISFOC) in Spain to showcase this new technology and to demonstrate the viability of its entry into the market.

NOTE ON THIN FILM TECHNOLOGY: First Solar--the leading producer of Thin-Film solar cells--averages $1250 per KW for a panel. The Prometheus Institute in Cambridge, MA has predicted that this price will drop to $650 per kW in 2012 and will have a manufacturing productivity of 1.39GW. In the same year, First Solar will be followed by Miasolé with .9GW, Sharp with .8GW, Nanosolar with .49GW, and United Solar with .36GW.

NOTE ON PV IN CALIFORNIA: At a cost of $3,500 per kW ($875 Million), Southern California Edison plans to install 250MW of PV solar panels on more than 5 million square feet of roofs and commercial buildings in southern California.

NOTE ON THE VATICAN TAKING ON SIN FREE SOLAR: Of all things green and religious, the Vatican is entering the fold with a reduction of social sinning with a substantial investment in solar energy. The Vatican will reduce its polluting ways (labeled as a modern evil sin) by building a $660 million solar power facility. Underscored by "thou shall reduce thy carbon footprint" is driving the construction of the 100 MW power plant on over 740 acres (300 hectares) of land. And it may be yield a profit by taking advantage of Italy's 20-year feed-in-tarrif solar subsidies ranging from $0.57 to $0.63 per kilowatt-hour. Given the cost of electrical energy in the U.S. averaging $0.10 per kilowatt-hour, this would be a smart return on investing in heavenly electricity.Scheduled to open in 2014, solar energy production will be utilized for the 900 inhabitants and facilities of the Vatican city and the remaining 95% of the renewable energy will be exported and sold to local utilities. The land for the solar installation was donated by Italy to the Church and is called Santa Maria di Galeria.

SOLAR PV Companies

Nanosolar

Sacryr Vallehermoso SA

Solar Millenium AG

E-Ton Solar Tech

Motech Industries

Fotosolar

NextEra Energy Resources LLC

SunRun

Phoenixsolar

SunPower Corp.

Solyndra