Solar Photovoltaics and CIGS
Electrical Energy
Worldwide demand for electricity is expected to significantly increase over the next 20 years. The Energy Information Administration of the U.S. Department of Energy estimates that world net electricity consumption will nearly double by 2025.
The overwhelming majority of electricity is currently produced using hydrocarbon sources (natural gas, coal, petroleum). Volatile prices and environmental and political concerns pertaining to fossil fuels have increased interest in electricity created using renewable, clean energy sources such as solar.
The Opportunity
According to the US Department of Energy, PV systems presently represent less than 1% of world energy production and are being adopted as a means to address both rural electrification in remote areas and as supplemental energy sources in grid-connected areas of the world. The market for PV products worldwide has increased over the last six years at an average annual growth rate of over 40%, driven by major governmental incentive programs in Germany, Spain, Japan and the United States. The market for PV systems reached approximately 3.4 Gigawatts in 2007, with a total installed base of approximately 10GW. By 2010, analyst predictions suggest the annual product market size could range from 5-15 GW worldwide. Some industry analysts postulate an industry potential of up to $1 trillion dollars by 2025.Solar Photovoltaics
Solar cells work by absorbing light and converting it to electrical power, referred to as the photovoltaic effect. The majority of commercial solar cells in use today are made of silicon, the same semiconductor material used in the microelectronics industry. In addition to the semiconductor materials, solar cells consist of a top and bottom electrical contact to move the electricity out of the solar cell. The performance of a solar cell is measured in terms of its efficiency in converting sunlight into electricity. Typical commercial solar cells have an efficiency ranging between 6% and 18%, meaning that for every 1,000 watts of sunlight striking a solar module, 60 to 180 watts of electricity will be produced.
The bulk of today's market is served with expensive silicon semiconductor wafer material, which shares its demand with the volatile integrated circuit industry. Although silicon is abundant in the earth's surface, processing it to a suitable pure crystalline form is energy and capital equipment intensive, resulting in recent supply shortages and high costs. Uncertain raw material costs for photovoltaic grade silicon continue to suggest a demand that far out paces the supply in the foreseeable future.
Photo Courtesy: Blitzstrom Thin Film Installation
Thin Film Photovoltaics
Solar cells and modules made from certain thin film semiconductors have been shown to be much less expensive to produce in larger volume and requiring much less raw material to produce than silicon based PV cells. Extensive research and development on thin film cells has been conducted for more than 30 years, and recent advances in manufacturing and product commercialization have increased worldwide share of thin film photovoltaics to over 10% in 2007.
Thin film photovoltaic products exhibit the following attributes:
- Scaleable, low cost manufacturing: Thin film solar cells and modules require a structural "substrate" to support them, such as glass. Applying the films on low cost glass substrates enables continuous and scaleable manufacturing. As much of the equipment to process these substrates is used in other industries, the capital expenditure required to establish large-volume thin film PV product manufacturing plants enables rapid capacity expansion and lowers the cost per watt of products.
- Lower material cost: The substrate and raw materials used in thin film PV products are less expensive than the cost of most semiconductor materials. With increasing thin film manufacturing capacity and process yield improvements product costs are reduced.
- Performance attributes: In addition to cost per watt advantages, thin film photovoltaic technologies exhibit performance advantages in generating energy in low light level and increased temperature environments. This positions them particularly well for applications in regions with less direct sunlight, such as in Northern Europe.
CIGS
Of the three thin film technologies currently being commercialized, solar cells and modules based on copper indium gallium di-selenide (CIGS) have shown the highest laboratory electrical conversion efficiency, can be produced on low cost glass substrates, hold promise for low cost manufacturing, and are highly scalable to high volume manufacturing.