Solar Energy 101: Part I

a guest post by Ken Whiteside, Director of Business Development at ONTILITY, LLC.

Solar 101
 

Welcome to the Graybar solar blog. We are looking forward to posting useful, timely information about solar energy; technologies, markets, policies, trends and any other interesting items that come to our attention. We hope you find the information here useful and enjoyable.

To get started, let’s look at solar energy in general and solar electricity in particular. Solar energy is used in two ways: one to produce heat, the other to produce electricity.

Producing heat from the sun is fairly easy to understand: Circulate a fluid through a set of tubing exposed to sunlight, then pass that hot fluid through a heat exchanger to heat up whatever it is you want to make hot – typically potable water or space-heat air. The technology involved is fluid dynamics and the equipment, aside from the solar heat collectors themselves, is from the plumbing industry. This technology, when coupled with reflectors and other concentrating devices, can be used to produce electricity. The heat from the sun is used to produce steam which then drives a typical turbine-generator combination – the same as is found in a natural gas fueled power plant. This technology is called concentrating solar power or CSP.
 
Producing electricity directly from the sun, while more technologically complex, is also quite easy to understand. It relies on the photovoltaic (PV) effect. When certain semi-conductor materials (most commonly forms of silicon blended and coated with other chemical elements) are exposed to sunlight, an electric current is produced. So, it is a direct transduction of sunlight into electricity. The PV effect was first observed about 170 years ago and its first widespread uses were by telecom companies to power remote signal repeaters, and by NASA to power spacecraft and satellites. So, while we’ve known about the PV effect for a long time, and made limited use of it a half century ago, it has been only within the past couple of decades that it has become a viable energy source for widespread use.
 
Building on technologies and manufacturing methods pioneered by the computer chip makers, solar PV technology over the past 20 years has been marked by steady progress toward greater efficiencies – more power out of a smaller space at a lower cost. At the start of this century, PV module prices were just under $10 per Watt; by 2006, they had fallen to around $5/W. As recently as 2009, prices were $3/W and in early 2013, they dropped to $0.50/W for large-scale projects. It must be noted that some of the price drop during the past 12 months was due to an enormous imbalance between module supply and global demand. That glut has mostly been absorbed now. At mid-year 2013, prices are up a bit, but are still well below $1/W. Simultaneous with this price drop, efficiency, the percentage of total solar energy that is converted to electricity, has followed a similarly steep upward path. Between 2009 and 2013, module efficiency has improved by 40-50%.
 
Next, we’ll address how the current produced by the semi-conductor material that makes up PV cells gets aggregated and turned into useful energy.
 
Ken Whiteside photo Ken Whiteside has been a fan of solar energy for decades. His first hands-on experience was installing solar on off-grid houses around Telluride, Colorado in the 1990’s (summer in the San Juan Mtns. - somebody had to do it). From his home in Austin, Ken writes and works for widespread adoption of solar electricity, smart energy production and use, and sustainability.
 

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