History Of Solar Power
The model for the fusion power plant, the sun, is a source of practically unlimited energy, most of which is wasted but nevertheless provides us with millions of kilowatts of power, keeps us warm, and grows all our food. To top it off, solar energy is safe, pollution-free energy on and in which living things have thrived since they first appeared on earth.
Every day the sun showers Earth with several thousand times as much energy as we use. Even the small amount that strikes our roof is many times as much as all the energy that comes in through electric wires. With the sun straight overhead, a single acre of land receives some four thousand horsepower, about equivalent to a large railroad locomotive. In less than three days the solar energy reaching Earth more than matches the estimated total of all the fossil fuels on Earth!
The logical question at this point is, Why are we not making use of this incredible bonanza in the form of solar energy? The answer, of course, is that we are using it, and have been from the beginning. All our energy-except nuclear- comes originally from the sun. A solar-powered radio draws on the sun directly, but a gasoline fueled automobile also uses solar energy, stored solar energy, in which the sunshine of ages ago was trapped in the earth until reclaimed by oil drillers. The challenge is to make use of solar energy directly and in a non-polluting fashion.
The Russian philosopher, Kuzma Prutkov, decided that the moon is more useful than the sun, since it shines at night when light is needed; while the sun is of little use in the daytime since it is light anyway! In such a fashion we, too, have dismissed the importance and potential of the sun. It appears that the fruitful application of solar energy is destined to wait until the bottom of the energy stockpile the sun has willed us is depleted.
Now is the time to make realistic goals and strategies to harness the power of the sun
The harnessing of solar energy is not new in fact, development of solar energy dates back more than 100 years, to the middle of the industrial revolution. Several pioneering solar power plants were constructed to produce steam from the heat of the sun, which was used to drive the machinery of the time. At the same time, Henri Becquerel discovered the photovoltaic effect; that is, the production of electricity directly from the sun. Becquerel’s research was investigated and extended by, among others, Werner Siemens. Photovoltaic power remained a curiosity for many years, since it was very inefficient at turning sunlight into electricity.
Early photovoltaic applications were geared more towards sensing and measuring light (such as a camera’s light meter) than towards producing power. With the advent of the transistor and accompanying semiconductor technology, however, the efficiency of photovoltaic power increased dramatically. Photovoltaic power became more practical. Over the years, many companies, including Siemens Solar, have worked to increase the efficiency of photovoltaic power. Today, commonly available solar panels are 16% efficient, which is four times greater than only a few years ago. Today, solar power is still used in two primary forms: thermal solar, where the heat of the sun is used to heat water or another working fluid, which drives turbines or other machinery to create electricity; and photovoltaic, where electricity is produced directly from the sun with no moving parts.
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.
Discrete Cell Technology
Monocrystalline (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 30-percent efficiency, with commercial modules of single-crystal cells exceeding 20-percent. Bifacial modules have proven to exceed 22% efficiency. Bifacial solar modules can produce light from both sides of the cell through two cells or transparent backsheets.
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.
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
Advantages of Photovoltaic Power
Photovoltaic solar power is one of the most promising renewable energy sources in the world. Compared to nonrenewable sources such as coal, gas, oil, and nuclear, the advantages are clear: it’s totally non-polluting, has no moving parts to break down, and does not require much maintenance. A very important characteristic of photovoltaic power generation is that it does not require a large scale installation to operate, as different from conventional power generation stations. Power generators can be installed in a DISTRIBUTED fashion, on each house or business or school, using area that is already developed, and allowing individual users to generate their own power, quietly and safely.
Rooftop power can be added as more homes or businesses are added to a community, thereby allowing power generation to keep in step with growing needs without having to overbuild generation capacity as is often the case with conventional large scale power systems But even when photovoltaic power is compared to other renewable energy sources such as wind power, water power, and even solar thermal power, there are some obvious advantages. First, wind and water power rely on turbines to turn generators to produce electricity. Turbines and generators have moving parts that can break down, that require maintenance, and are noisy. Even solar thermal energy needs a turbine or other mechanical device to change the heat energy of the sun into mechanical energy for a generator to produce electric power. Photovoltaic power, by contrast, is generated directly from the sun. PV systems have no moving parts, require virtually no maintenance, and have cells that last for decades.
Uses of Solar
How practical is solar for home and mobile home/marine use? These days, it’s pretty practical. Until solar power came along, people who wanted to live in remote areas frequently had to pay large fees to have a power cable run to their house. Now, a remote home can be virtually self-sufficient with solar power. Even in areas where power lines are nearby, solar may be a viable alternative to being connected to a power company. An average home has more than enough roof area to produce enough solar electricity to supply all of its power needs. With an inverter, which converts direct current (DC) power from the solar cells to alternating current (AC), which is what most home appliances run on, a solar home can look and operate very much like a home that is connected to a power line. For recreational vehicles, solar power provides the freedom to go to more remote locations, without relying on a plug-in power source or a noisy electric generator. Systems for RV’s can be small for charging batteries only or large enough to power the entire vehicle for a period of time. Similarly, boats can use solar power for many of their power needs, rather than a generator or engine.
Solar PV Power in Industry
Grid- Connected residential and commercial are viable and effective and quickly becoming a mainstream technology.
Some of the most important applications of solar energy are nearly invisible
Telecommunications, oil companies, and highway safety equipment all rely on solar power for dependable, constant power, far from any power lines.
Call Boxes: look at any California roadside call box, and you’ll see a solar panel. California standardized on the use of solar power and cellular phones to eliminate the need for any buried cable connections to these phones. Given the sometimes literally life-saving nature of these call boxes, dependability is a must.
Roadside signs: solar power is used for many lighted highway signs, eliminating the need for diesel generators.
Telecommunications installations: when you need a microwave repeater on a remote mountaintop, the last thing you want to do is run a power line up to it. For reliable power, many communications repeaters in remote areas use solar.
Homes incorporate solar power at the time that they are built, as well as retrofit, dramatically reducing both the cost of buying solar power and the cost of utility bills. New communications technology makes living in remote areas a practical reality given the availability of solar power. Mobile uses will undoubtedly increase. And industrial applications will continue to enjoy the versatility of solar power.