The science of solar lighting is called photovoltaic and was derived primarily from the United States space program and satellite technology. Photovoltaic (PV) cells are primarily made of semiconductors and silicon cells. Simply put, when sunlight strikes the semiconductor it is absorbed into the material. The energy created from “the strike” allows the electrons to flow creating an electric current. The current then sends energy to the power supply (rechargeable battery) which in turn energizes the lamp (LED). The efficiency (or light output) is based upon several factors—cell capacity, lamp source, battery type and the PC board design.
The most popular solar lamp (bulb) is LED (light emitting diode). This type of lamp is so efficient that they are now found in everything from automotive brake lights to city traffic signals. LED’s come in a variety of colors, the most intense being super white. LED lamps have different properties and characteristics than conventional light bulbs and the measurement terminology is foreign to most people. For example, LED lamp intensity is measured in milli-candles (mcd) as opposed to watts and lumens, milli-amps (ma) rather than amps and beam spreads are measured in viewing angles (20-60 degree avg. ) instead of flood or spot.
Professional solar lighting products are equipped with super bright, efficient LED (light emitting diodes) lamps that produce an intense cool white glow that has often been referred to as a “moon light effect. ” It is important to recognize that outdoor solar lighting products are “site sensitive” and perform best when placed in direct sunlight and away from shadowy areas. It is also important to note that the operating conditions of solar lighting will fluctuate with cloudy, rainy and winter-like weather. However, as solar technology continues to develop solar cells will become more “sensitive” and begin to attract even partial ambient light.
The key elements of solar lighting products are battery and lamp type. Most solar lights are equipped with rechargeable NiCAD (nickel cadmium) batteries. However, a better choice is NiMH (nickel metal hydride). This type of rechargeable battery has a much better memory than NiCAD and is non-polluting to the environment.
Granted, there is so much more to photovoltaic science and LED technology than can be said here but what seems like magic is simply good science at work. We have already seen significant improvements in the efficiency of solar products as demand for this technology continues to grow. Solar power is now part of everyday products such as calculators, clocks, water pumps, irrigation controllers and more! It can be said we have entered into a new “energy” renaissance and solar lighting is just one of the aspects to this revolution.
Finally, as the U. S. And the rest of the world continues to grapple with higher energy costs with dwindling non-renewable supplies (such as coal, oil and petroleum products) renewable energy sources such as solar power will become even more important.
Summary-Solar powered lighting is now being requested by more homeowners, designers and architects than ever before. Improvements in solar circuits, LED lamps and rechargeable batteries now make solar lighting a viable choice for outdoor lighting. Manufacturers are now offering solar lighting products in a wide array of designs and applications. Solar lighting provides new solutions and alternatives to conventional lighting products that, until recently were not possible
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