Solar Electric Systems – History

    Solar energy—power from the sun—is a vast and inexhaustible resource. Once a solar electric system is in place to convert it into useful energy, the fuel is free and will never be subject to the ups and downs of energy markets. Furthermore, it represents a clean alternative to the fossil fuels that currently pollute our air and water, threaten our public health, and contribute to global warming. Given the abundance and the appeal of solar energy, this resource is poised to play a prominent role in our energy future.

    In the broadest sense, solar energy supports all life on Earth and is the basis for almost every form of energy we use. The sun makes plants grow, which can be burned as “biomass” fuel or, if left to rot in swamps and compressed underground for millions of years, in the form of coal and oil. Heat from the sun causes temperature differences between areas, producing wind that can power turbines. Water evaporates because of the sun, falls on high elevations, and rushes down to the sea, spinning hydroelectric turbines as it passes. But solar energy usually refers to ways the sun’s energy can be used to directly generate heat, lighting, and electricity.

    Solar Electric Systems:  A brief history & major milestones…

    The most commonly used solar technology is solar photovoltaic (PV).  Photovoltaic’s is a method of generating electrical power by converting solar radiation into direct current electricity (DC)  using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of cells containing a photovoltaic material. The semiconductor materials presently used for photovoltaics include monocrystalline silicon, silicon, amorphous, cadmium telluride, and copper indium.

    The photovoltaic effect is the creation of a voltage in a material upon exposure to light.  This is nothing new as it was first observed in 1839.  Albert Einstein‘s later described the photoelectric effect in one of his 1905 papers, named “On a Heuristic Viewpoint Concerning the Production and Transformation of Light”. His simple explanation in terms of absorption of photons explained the features of the phenomenon and the characteristic frequency. Einstein’s explanation of the photoelectric effect won him the Nobel Prize in Physics in 1921.

    In 1958 the Vanguard I space satellite used a small (less than one watt) array to power its radios.  Later that year, Explorer III, Vanguard II, and Sputnik-3 were launched with PV-powered systems on board.  Despite faltering attempts to commercialize the silicon solar cell in the 1950s and 60s, it was used successfully in powering satellites.  It became the accepted energy source for space applications and remains so today.

    In 1973 the University of Delaware builds “Solar One,” one of the world’s first photovoltaic (PV) powered residences. The roof-integrated arrays fed surplus power through a special meter to the utility during the day and purchased power from the utility at night. This was the first example of the now popular grid tied solar system and would act as model for things to come.

    In summary, the following is a list of advantages when considering installing a solar electric system.

    Advantages

    • Electricity produced by solar cells is clean and silent. Because they do not use fuel other than sunshine,  solar electric systems do not release any harmful air or water pollution into the environment, deplete natural resources, or endanger animal or human health.
    • Photovoltaic systems are quiet and visually unobtrusive.
    • Small-scale solar plants can take advantage of unused space on rooftops of existing buildings.
    • PV cells were originally developed for use in space, where repair is extremely expensive, if not impossible. PV still powers nearly every satellite circling the earth because it operates reliably for long periods of time with virtually no maintenance.
    • Solar energy is a locally available renewable resource. It does not need to be imported from other regions of the country or across the world. This reduces environmental impacts associated with transportation and also reduces our dependence on imported oil. And, unlike fuels that are mined and harvested, when we use solar energy to produce electricity we do not deplete or alter the resource.
    • A PV system can be constructed to any size based on energy requirements. Furthermore, the owner of a PV system can enlarge or move it if his or her energy needs change. For instance, system owners can add modules as their energy usage and financial resources grow.