Solar Technology Today

Photovoltaic power can be produced in many ways, with widely varying efficiency and costs. They can be divided into two basic groupings: discrete cell technology and integrated thin film technology.

Solar Thermal

Discrete Cell Technology

Single-crystal silicon

Sliced from single-crystal boules of grown silicon, these wafers/cells are now cut as thin as 200 microns. Research cells have reached nearly 24-percent efficiency, with commercial modules of single-crystal cells exceeding 15-percent.

Multicrystalline silicon

Sliced from blocks of cast silicon, these wafers/cells are both less expensive to manufacture and less efficient than single-crystal silicon cells. Research cells approach 18-percent efficiency, and commercial modules approach 14-percent efficiency.

Dendritic web

A film of single-crystal silicon pulled from a crucible of molten silicon, like a soap bubble, between two crystal dendrites. Gallium Arsenide (GaAs) A III-V semiconductor material from which high-efficiency photovoltaic cells are made, often used in concentrator systems and space power systems. Research cell efficiencies greater than 25 percent under 1-sun conditions, and nearly 28 percent under concentrated sunlight. Multijunction cells based on GaAs and related III-V alloys have exceeded 30-percent efficiency.

Integrated Thin Film Technology

Copper Indium Diselenide (CuInSe2), or CIS
A thin-film polycrystalline material, which has reached a research efficiency of 17.7 percent, delivers the highest completed module efficiency for full sized power modules, reaching over 11 percent. Amorphous Silicon (a-Si) Used mostly in consumer products for solar watches and calculators, a-Si technology is also used in building-integrated systems, replacing tinted glass with semi-transparent modules. The primary issue with a-Si technology remains the low efficiency and associated greater requirement for space and higher array installed cost and weight

Cadmium Telluride (CdTe)

A thin-film polycrystalline material, deposited by electrodeposition, spraying, and high-rate evaporation. Small laboratory devices approach 16-percent efficiency, with commercial-sized modules (7200-cm2) measured at 8.34-percent (NREL-measured total-area) efficiency and production modules at approximately 7 percent.

Solar Concentrators

Solar energy is the southwest’s most abundant renewable resource. Indeed, the Department of Energy has conducted resource assessments to evaluate the generating potential of potential project sites and has found that Nevada, New Mexico, California, Arizona, Utah and Texas have enough combined potential project sites to provide up to 6800 MW of generating capacity-Roughly equivalent to seven times the country’s current electricity generating capacity. CSP technology is the least expensive solar technology for providing large quantities of electrical power, and with sufficient storage, it can deliver baseload power. CSP power plants do not require any fuel, exhibit low variable operating costs, and can be quickly constructed from basic commodity materials such as concrete, glass, and steel