Solar power is energy which comes from the sun. This energy is very powerful and hits the earth regardless of whether or not we take advantage of it. Even the tiny percentage of sunlight that touches the earth is plenty to meet the energy and power needs of the entire human population more than 8,500 times over.
Solar collectors and modules are designed to capture some of the sun’s energy and change it from radiation into more usable forms such as heat or electricity. In fact, sunlight is an excellent source of heat and electricity, the two most important forms of energy humans consume.
Solar power is an endless source of natural energy that can be converted to electrical energy. What makes it appealing is that it is a completely free and inexhaustible fuel source and no fuel, waste, or pollution is expelled in its usage.
Photovoltaic (PV) cells, or solar cells, convert sunlight directly into electricity. As the sun strikes a PV cell, the semi-conducting materials within the cell absorb the sunlight, producing electricity. Solar cells are often used as simple systems that power small calculators and wristwatches. More complicated systems provide electricity for pumping water, powering communications equipment, lighting homes, and running appliances. A series of solar cells form a PV array or solar panel. Between 10 and 50 solar panels are needed to power an average household. PV panels are installed on buildings in places of maximum sun and minimal shade in order to take full advantage of the sun's power. There is very little maintenance required to sustain solar equipment. Panels that are kept clean, can last 20 to 30 years.
Solar power can be used in a grid-tied system or in a distributed system. A solar grid-tied system links a series of solar panels through a power inverter to the utilities electric grid. The solar panels generate a direct current (DC) by drawing on energy from the sun. The inverter then converts that direct current to an alternating current (AC), which electronic devices and appliances can use. Batteries are not necessary to supplement the system and any excess electricity generated by the solar panels is redirected by the inverter back into the grid where it can be used on other premises.
Distributed systems work independently from a utilities electric grid, using batteries to store the power. Similar to a grid-tied system, distributed solar panels typically use a power inverter to convert the direct current from the sun into an alternating current, to be used on location. However, some systems function without an inverter and run only DC appliances.
Solar panels and how they convert the energy to electricity
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 Hot Water basics
Solar water heating systems are an excellent application of solar energy because hot water is needed year round, including the summer when we receive a lot of sunlight.
Water heating is usually the second highest energy need, after space heating, in homes. For a family of four, water heating is approximately one-quarter of the family’s energy consumption. Numerous conservation measures can be implemented to reduce this cost. Low flow showerheads, temperature reductions, tank and pipe insulation are a few of the cost-effective energy measures that should be implemented prior to considering a solar hot water system.
The concept of heating water with solar energy is very simple. A good example of solar water heating is a garden hose left out in the sun. The hose absorbs the sun's energy, turns it into heat and transfers it to the water. Some solar water heaters are not much more complicated than this simple example.
Solar water heating can be used to produce hot water for a wide variety of uses. Obvious uses include washing, cooking, cleaning, and any other domestic uses of hot water around the home. However, applications are not limited to residential structures. Solar water heating is also common for service hot water in commercial and institutional buildings.
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