This general information guide to solar panels will provide a breif overview of solar energy topics and address the following questions:
The solar revolution of the last two decades has made solar energy an increasingly powerful force in the energy arena. Solar Panels use arrays of solar photovoltaic cells to convert photons into usable electricity. With solar panels, we are provided with clean, renewable energy from the sun. Click below to navigate through our general solar panel information guide and read more about how solar panels work, how they are made, and how they will affect your world.
Solar Panels are a form of active solar power, a term that describes how solar panels make use of the sun's energy: solar panels harvest sunlight and actively convert it to electricity. Solar Cells, or photovoltaic cells, are arranged in a grid-like pattern on the surface of the solar panel. These solar voltaic cells collect sunlight during the daylight hours and covert it into electricity.
Solar panels are typically constructed with cystalline silicon, which is used in other industries (such as the microprocessor industry), and the more expensive gallium arsenide, which is produced exclusively for use in photovoltaic (solar) cells.
Other, more efficient solar panels are assembled by depositing amorphous silicon alloy in a continuous roll-to-roll process. The solar cells created from this process are called Amorphous Silicon Solar Cells, or A-si. Solar Panels constructed using amorphous silicon technology are more durable, efficient, and thinner than their crystalline counterparts.
For very important solar projects, such as space probes that have to rely on solar energy, very-high efficiency solar cells are constructed from gallium arsenide by a process called molecular beam epitaxy. Solar cells constructed by this process have several p-n junction diodes, each designed to be maximally efficient at absorbing a given part of the solar spectrum. This solar panels are much more efficient than conventional types, but the process and materials involved make them far too expensive for everyday applications. The newest solar panels function on the molecular or quantum level, and represent an exciting new technology coming into play. These solar panels are created by implanting carbon nanotubes or quantum dots into a treated plastic. Unlike silicon-based solar panels, these solar panels do not have to be constructed in a clean room, and therefore production costs are somewhat dimished.
The practical applications of solar panels constructed from plastics are staggering - they could be overlayed onto a laptop screen to provide continous power, or provide supplemental power to any number of outdoor appliances. The primary hurdle for this new technology is efficiency, and these 'plastic' solar panels have an operational efficiency of about .11% of their silicon-based counterparts. The only short-term solution to this energy problem is for these plastic solar panels to generate electricity from light outside the visible spectrum of light. Some highly-experimental plastic solar panels have been made to absorb infrared energy, and if a solar panel is made that can absorb both infrared energy and light from the visible spectrum, the operational efficiency could increase up to thirty percent.
In direct sunlight at the surface of the equator, a maximally efficient photovoltaic cell about 1/5m in diameter creates a current of approximately 2 amps at 2 volts, however, due to the Earth's atmospheric interference, terran solar panels will never perform as well as solar panels exposed directly to the sun's rays.
Years of overheating and physical wear can, however, reduce the operation efficiency of the photovoltaic unit. Solar cells become less efficient over time, and excess energy is released into its thermally conductive substrate as infrared heat.
The amount of power solar panels produce is influenced by the quality of the solar panel, the materials and technology used in making the solar panel, and the amount of time the solar panel has been in use. When purchasing solar panels, it is therefore wise to look beyond size and look at the dollars/watt ratio.
Solar energy originates in the depths of our sun. The sun endures a continuous stream of thermonuclear explosions as hydrogen atoms are fused into helium atoms. We encounter the resultant energy as radiation that strikes the surface of the earth. Solar panels convert this solar radiation into useful electrical energy and store them in batteries for our use. Enough solar radiation strikes the earth every day to meet earth's energy needs for an entire year. Solar panels help us harvest this energy and convert it into usable energy to meet the everyday needs of modern life.
Solar panels collect solar radiation from the sun and actively convert that energy to electricity. Solar panels are comprised of several individual solar cells. These solar cells function similarly to large semiconductors and utilize a large-area p-n junction diode. When the solar cells are exposed to sunlight, the p-n junction diodes convert the energy from sunlight into usable electrical energy. The energy generated from photons striking the surface of the solar panel allows electrons to be knocked out of their orbits and released, and electric fields in the solar cells pull these free electrons in a directional current, from which metal contacts in the solar cell can generate electricity. The more solar cells in a solar panel and the higher the quality of the solar cells, the more total electrical output the solar panel can produce. The conversion of sunlight to usable electrical energy has been dubbed the Photovoltaic Effect.
The photovoltaic effect arises from the properties of the p-n junction diode, as such there are no moving parts in a solar panel.
Solar Insolation is a measure of how much solar radiation a given solar panel or surface recieves. The greater the insolation, the more solar energy can be converted to electricity by the solar panel. Click to learn more about solar insolation.
Other factors that affect the output of solar panels are weather conditions, shade caused by obstructions to direct sunlight, and the angle and position at which the solar panel is installed. Solar panels function the best when placed in direct sunlight, away from obstructions that might cast shade, and in areas with high regional solar insolation ratings.
Solar panel efficiency can be optimized by using dynamic mounts that follow the position of the sun in the sky and rotate the solar panel to get the maximum amount of direct exposure during the day as possible. For more information on solar panel efficiency through the use of mounts, see our section on solar panel mounts and accessories.
Making solar panels is a delicate process, and it is for this reason that major solar advances did not come into play until the lattermost quarter of the last century, when advances in semiconductors and photovoltaic design allowed increasingly efficient and affordable solar cells to be developed.
The creation of solar panels typically involves cutting crystalline silicon into tiny disks less than a centimeter thick. These thin, wafer-like disks are then carefully polished and treated to repair and gloss any damage from the slicing process. After polishing, dopants (materials added to alter an electrical charge in a semiconductor or photovoltaic solar cell) and metal conductors are spread across each disk. The conductors are aligned in a thin, grid-like matrix on the top of the solar panel, and are spread in a flat, thin sheet on the side facing the earth.
To protect the solar panels after processing, a thin layer of cover glass is then bonded to the top of the photovoltaic cell. After the bonding of protective glass, the nearly-finished panel is attached to a subtrate by an expensive, thermally conductive cement. The thermally conductive property of the cement keep the solar panel from becoming overheated; any leftover energy that the solar panel is unable to convert to electricity would otherwise overheat the unit and reduce the efficiency of the solar cells.
Despite these protective measures against the tendancy of solar panels to overheat, it is vital that when installing a solar panel, additional steps should be taken to ensure the solar panel is kept cool. Elevating the solar panel above ground to let the airflow underneath cool the device.
Amorphous silicon solar panels are a powerful, emerging line of photovoltaics, that differ in output, structure, and manufacture than traditional photovoltaics which use crystalline silicon. Amorphous silicon solar cells, or A-si cells, are developed in a continuous roll-to-roll process by vapor-depositing silicon alloys in multiple layers, with each extremely thin layer specializing in the absorption of different parts of the solar spectrum. The result is record-breaking efficiency and reduced materials cost (A-si solar cells are typically thinner than their crystalline counterparts).
Some Amorphous Solar Panels also come with shade-resistant technology or multiple circuits within the cells, so that if an entire row of cells is subject to complete shading, the circuit won't be completely broken and some output can still be gained.
The development process of Amorphous Silicon solar panels also renders them much less susceptible to breakage during transport or installation. This can help reduce the risk of damaging your significant investment in a photovoltaic system. Click here for more more information on amorphous silicon solar panels.
Solar panels of the same size may produce variable amounts of electricity - this discrepancy arises from variations in the functioning age of the solar cells, the quality of the solar cells, and with what technology they were produced. Early solar cells, for example, are not quite as efficient as modern solar cells, so you'll find that with a trusted solar panel manufacturer, quality increases as the technology involved becomes more advanced and precise.
As another example, two identical solar cells are purchased. One is left in storage and the other has been in use for three years. Solar panels have an effective lifespan of about 20 to 25 years, and their value and wattage output decrease steadily over time. The solar cell that has been in storage will be more valuable than one that has been actively converting sunlight to electricity for a long time.
In summary, although two solar panels may seem identical, there are a number of other factors you need to take into consideration. Just because a given solar cell is more expensive per square centimeter than another solar cell, it does not mean that the second one is a bargain. Quality, age, and technology all play a role in the cost of the solar cell.
The best way to compare the value of two solar cells is to measure the dollars/watt ratio. The current best deals on solar cells is about $4.30 per watt. For a 50 watt solar panel, your total cost will be about $215. Keep this in mind when asesssing the cost and purchasing solar cells and panels.
Newer panels may or may not be more cost effective for you, if you have ample mounting space for your solar panel, size shouldn't be a problem, so if you find that you are able to use more primitive technology for a cheaper dollar/watt price, go with it. You will save money for a marginal increase in mounting space. (this usually shouldn't be a problem)
Although there are numerous other methods of generating electricity, solar panels have a number of considerable advantages for both the consumer, the producer, and the environment.
Solar panels are used to power all sorts of electronic equipment, from solar-powered handheld calculators that will function as long as sunlight is available, to remote solar-powered sensor arrays in bouys, and even some experimental vehicles and boats. Solar panels are also placed on outdoor lighting structures - the solar cell is charged during daylight hours, and at night, we get free electricity to keep our streets well-lit and secure. Solar panels are used extensively on satellites, where array of solar cells provide reliable power for the satellite's electrical systems.
Solar Power plants, which are large collections of solar panels arranged to generate commercial electricity, are becoming more and more frequent these days. While still between 2-5 times as expensive to produce as electricity from fossil fuels, electricity generated from solar panels is free, nearly infinitely abundant, and non-polluting. Many environmentally-minded communities across America have set up solar power stations to help generate private or commercial solar energy.
Powering homes with solar power has also been a major part of the solar revolution the last two decades have seen. Solar panels can be placed on the roof of homes, businesses, or remote research stations, and can be used independent of or in conjunction with the local power grid.
Solar panels are clean - while generating electricity from sunlight, solar panels produce virtually no pollution, whereas burning fossil fuels releases large quantities of toxic gases into the atmosphere.
For the consumer, solar panels can free the individual from reliance on the power grid and the monopolistic energy supplier. Once you make the initial investment in hardware, you will have free electricity for years to come.
Fossil Fuels are limited - Although fossil fuel reserves are expected to run dry within the next century, solar power is clean, abundant, and will remain a renewable resource that can meet all of Earth's energy needs for billions of years to come.
Portability is a major advantage of the common small watting rating solar panel, which can be used in numerous electronic and handheld devices when off the electricity grid, or when lugging around a generator would be impractical or wasteful. Portable or device-mounted solar panels can power solar-powered calculators, laptops, and even small motorized vehicles. The applications are limitless, but as you will see, the costs of using solar panels are not to be trivialized.
Admittedly, while solar power is certainly much cleaner than the burning of fossil fuels, and moderately cleaner than the production of nuclear power, solar panels are very pricey and in many years demand for solar panels exceeds supply. When we ask ourselves - why are solar panels necessary, we must consider the costs of production as well as the costs of using much more harmful means of producing electricity. Solar Panels also require more square yardage per kilowatt for the power-generating facility than fossil fuel power plants or nuclear power.
As we previously mentioned, solar panels collect solar radiation from the sun and actively convert that energy to electricity. The solar cells on these solar panels make use of the extremely small fraction of the sun's energy that passes through earth's atmosphere and strikes the cells on the solar collector. The efficiency of these solar panels, and the resultant energy produced is dependant on many climatic, geographic, and weather-related factors. Arid climates are ideal for solar panels, and they will produce more energy in areas where they are exposed to direct sunlight under clear skies. But even at optimal efficiency, solar panels only convert a small percentage of the energy that strikes it into usable energy. The efficiency factors is in the teens for most solar cells. Advanced solar cells, like those used on the Voyager spacecraft, have much higher efficiency ratings, but are much too expensive to produce en masse for general purposes.
Solar panels have the ability to meet all of our energy needs, but at present we only use a tiny fraction of the energy that the sun has to offer. How much energy does the sun produce? How is it produced? And how much of the sun's energy can be theoretically harvested via solar cells?
Energy from the sun is caused from thermonuclear expolosions deep within the sun. These explosions fuse atoms of hydrogen into atoms of helium. A tremendous amount of energy is released during the thermonuclear reaction and the sun releases that energy as radiation. This radiation travels through space at the speed of light, and solar panels can make practical use of it. Our sun generates an enourmous amount of energy, and potentially, had we the technology to harvest that sunlight with solar arrays across the solar system, we could harvest huge amounts of energy.
According to our friends at Astronomy Cafe, we calculate the amount of energy given off the sun every hour as:
"3.8 x 10^33 ergs/sec or 3.8 x 10^26 watts of power, an amount of energy each second equal to 3.8 x 10^26 joules. In one hour, or 3600 seconds, [the Sun] produces 1.4 x 10^31 Joules of energy or 3.8 x 10^23 kilowatt-hours."
The sun produces more energy every hour than the entire energy needs of human civilization from the beginning of time. Solar panels will help us harvest increasing amounts of this abundance of energy to meet our energy needs in the future.
Panels of Solar cells that are damaged or otherwise rendered unsound during the manufacturing process are dubbed scrap solar cells; Scrap solar cells are essentially 'broken' solar panels. They are often sold at very cheap prices. Despite their reduced efficiency, you may be getting more watts for your dollar if you opt to buy scrap solar cells from a certified retailer. Read on to find out more about the advatanges and disadvantages of using scrap solar cells for your solar panel investment.
Scrap solar cells are advantageous in that they are generally much cheaper than standard solar panels. Many solar panel retailers offer scrap solar panels for sell, although due to their inferior quality they may not be explicitly advertized. Contact your solar panel retailer for more information on how to obtain panels scrap solar cells - you will find that they will be cheaper per kilowatt than your typical solar panel. Many scrap solar cell units sell for less than three (3) dollars per kilowatt of output. Price is the primary advantage in scrap solar cells, but be sure to review the disadvantages of purchasing scrap solar cells before diving in.
The disadvantages of scrap solar cells are many. Firstly, they are large and unsightly. Scrap solar cells suffer from reduced efficiency, even when sodered together expertly, so you will certainly have to buy a larger solar panel array than you would with conventional solar technology. Secondly, these solar cells require some knowledge of sodering, and may require additional mounting due to the increased size of the solar panel array. Scrap solar cells are reccomended only for the advanced consumer with considerable workbench experience and the willingness to sacrifice time, efficiency and space for a considerable increase in value.
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