Solar Panels and the Future of Solar Energy
In 1954, the first photovoltaic technology was created in the United States when Daryl Chapin, Calvin Fuller, and Gerald Pearson developed a silicon photovoltaic cell at Bell Labs. Photovoltaic technology is the means used to harness solar energy, and while it was born in 1954, it wasn’t until 1970 when Elliot Berman designed a cost effective “solar cell” that it could be used effectively on a larger scale.
Solar Cells, Modules, Panels, and Arrays
Solar, or photovoltaic, cells convert the sun’s energy into electricity. Cells are small, layered, square-shaped semiconductors mostly made from silicon and other conductive materials. The top layer is negatively charged (N-Type) and the bottom layer is positively charged (P-Type), a common design for direct current (DC) electricity.
Sunlight, comprised of photons, hits a solar cell and releases electrons from the silicon atoms. These energized electrons escape from the N-Type layer into the P-Type layer of the cell. Due to the differing atomic structures of the layers, the electrons flow in one direction, creating DC electricity. This process is called the “photovoltaic effect”, first discovered in 1839 by Edmund Becquerel, a French experimental physicist.
One solar cell produces a small amount of power, so they are grouped together in modules. Multiple modules assembled as a unit are defined as a solar panel. Any number of panels generating power as a unit are considered a solar array, or solar farm. Agua Caliente, in Arizona, is one of the largest solar arrays in the world.
U.S Solar Farms
Agua Caliente came online in 2012, utilizing a little over 5 million solar panels. The facility generates 290 MW of power to fuel 230,000 homes in nearby California. Prior to Agua Caliente, the largest U.S facility generated only 20 MW of power.
In contrast to Agua Caliente, Solar Star solar near Rosamond, California produces a whopping 579 MW and is the largest solar facility in terms of installed capacity. The Solar Star array is comprised of 1.7 million panels, relying on higher efficiency panels instead of sheer quantity.
Direct Current (DC) to Alternating Current (AC) Conversion
DC electricity generated by solar panels flows in one direction, whereas AC electricity flows both directions along a wire. AC is easily sent over long distances and utilized by the U.S electricity networks. Solar panels generate DC which is converted through a connected solar power inverter into AC. Most electronics are powered through AC, but devices such as laptops and phones use DC. The network’s AC electricity is converted once more by a rectifier back to DC for these devices.
Advantages and Disadvantages of Solar Energy
Solar energy utilization has shown growth with more than 800,000 households boasting solar panels. As a clean and free renewable energy, benefits can be found in both cost-effectiveness and environment protection. A 5 panel (3.75 kW) system can replace about 80% of the energy normally taken from the grid. A homeowner can save around $1,000 a year on electricity by installing solar panels on the roof, and reduce the household carbon footprint by 2.48 tons.
Utility companies and the government offer incentives as well to promote renewable energy facilitation. “Net metering” is an arrangement where the utility company credits the household account for clean energy given to the grid. Another, the “feed-in tariffs”, pays a premium to a household for clean energy fed into the grid, potentially generating revenue. The government offers tax credit (deduction from taxable income), solar rebates (one time solar energy investment), and State Renewable Energy Credits (buy and sell on the open market).
The Future of Solar Energy
Now solar energy comprises .6% of U.S electricity generation according to a 2015 report from the US Energy Information Administration. U.S installations have grown from 1.2 GW in 2008 to 30 GW in 2015; enough capacity to power 5.7 million average American homes. Due to the cost of solar panels dropping 60% in the past 5 years, the demand and application has increased, taking further advantage of the renewable resource.
Unfortunately, solar energy is not perfect yet. The cost of solar panels and equipment is high compared to fossil fuel based energy. Fabrication involves caustic chemicals and produces greenhouses gases rivaling solar energy’s clean and efficient purpose. Furthermore, sunlight is not constant and varies dependent on location, time, season, and weather. The lack of reliability is a major obstacle that multiple companies have been working to overcome.
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