Solar Energy Basics

SOLAR

Technology
Most R&D is focusing on two main solar technologies: photovoltaics and concentrated and concentrated solar power.

Photovoltaic (or PV) uses solar cells to convert sunlight into electricity. Solar cells are postage-stamp sized clusters of semiconductors that connect together to form modules. Modules connect together to form a PV array, which are the shiny silver panels you see on rooftops. The physics of the process is well-described at the DOE's renewable energy site.

PV Benefits

• is costing increasingly less to produce and use, thus becoming more affordable and available
• no air pollution, fuel inputs or combustion
• only hazardous waste is only small amounts of chemicals in PV factories
  
• style is modular and thus easy and flexible to mass-produce
  
• reliable and requires little maintenance (can be 80% efficient even on cloudy days)
  
• economic benefits like price stability relative to fossil fuels
  

The second technology, concentrated solar power (or CSP) uses mirrors to reflect and concentrate sunlight onto receivers. The receivers convert this energy to heat, which then produces steam to turn a turbine and, finally, drive a generator.

CSP Benefits

• generates fairly inexpensive electricity
• can deliver power during peak demand
  
• can be integrated with low-cost thermal storage
  

Local Scoop
Colorado has really jumped on solar. Denver is one of DOE's 25 Solar America Cities, a program designed to spur innovation and "help lay the foundation for a solar energy market that can serve as a model for cities around the nation."

The program is a partnership between DOE, industry, universities, state and local government and NGOs. There are a few Boulder participants we may want to look at/contact, including:

• Colorado Power Industries
• Sinton Consulting, Inc.
• testing crystalline silicon cells and modules
• Sunwave Lighting
• working on an efficient cell that can generate more light from less energy
• Xcel Energy
  

NREL is doing super-innovative technical testing on thermal storage methods (needed for concentrated solar) such as heat-transfer fluids and storage vessels described here.

"NREL is studying a new class of nanofluids that possess enhanced thermophysical properties including thermal conductivity, heat capacity, freezing point, boiling point, and high-temperature thermal stability."

Policy Mechanisms to make solar more viable

• Renewable portfolio standards
• Emissions credits
• Production and investment tax credits for large systems
• State and federal tax credits for small systems
• Other buy-downs or credits for installation of a solar system
• Favorable mortgage interest rates for solar-equipped buildings.

Glossary
DOE put together a comprehensive solar glossary, which alleviates us of that task.