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Photovoltaic solar panels absorb sunlight as a source of energy to generate direct current electricity. A photovoltaic (PV) module is a packaged, connected assembly of photovoltaic solar cells available in different voltages and wattages. Photovoltaic modules constitute the photovoltaic array of a photovoltaic system that generates and supplies solar electricity in commercial and residential applications.

The most common application of solar energy collection outside agriculture is solar water heating systems.[1]

Theory and construction

See also: Solar cell

Photovoltaic modules use light energy (photons) from the Sun to generate electricity through the photovoltaic effect. Most modules use wafer-based crystalline silicon cells or thin-film cells. The structural (load carrying) member of a module can be either the top layer or the back layer. Cells must be protected from mechanical damage and moisture. Most modules are rigid, but semi-flexible ones based on thin-film cells are also available. The cells are connected electrically in series, one to another to a desired voltage, and then in parallel to increase amperage. The wattage of the module is the mathematical product of the voltage and the amperage of the module.

A PV junction box is attached to the back of the solar panel and functions as its output interface. External connections for most photovoltaic modules use MC4 connectors to facilitate easy weatherproof connections to the rest of the system. Also, a USB power interface can be used.

Module electrical connections are made in series to achieve a desired output voltage or in parallel to provide a desired current capability (amperes) of the solar panel or the PV system. The conducting wires that take the current off the modules are sized according to the ampacity and may contain silver, copper or other non-magnetic conductive transition metals. Bypass diodes may be incorporated or used externally, in case of partial module shading, to maximize the output of module sections still illuminated.

Some special solar PV modules include concentrators in which light is focused by lenses or mirrors onto smaller cells. This enables the use of cells with a high cost per unit area (such as gallium arsenide) in a cost-effective way.

Solar panels also use metal frames consisting of racking components, brackets, reflector shapes, and troughs to better support the panel structure.[2]

History

See also: Solar cell#History and Timeline of solar cells

In 1839, the ability of some materials to create an electrical charge from light exposure was first observed by Alexandre-Edmond Becquerel.[3] Though the premiere solar panels were too inefficient for even simple electric devices they were used as an instrument to measure light.[4] The observation by Becquerel was not replicated again until 1873, when Willoughby Smith discovered that the charge could be caused by light hitting selenium. After this discovery, William Grylls Adams and Richard Evans Day published "The action of light on selenium" in 1876, describing the experiment they used to replicate Smith's results.[3][5]

In 1881, Charles Fritts created the first commercial solar panel, which was reported by Fritts as "continuous, constant and of considerable force not only by exposure to sunlight but also to dim, diffused daylight."[6] However, these solar panels were very inefficient, especially compared to coal-fired power plants. In 1939, Russell Ohl created the solar cell design that is used in many modern solar panels. He patented his design in 1941.[7] In 1954, this design was first used by Bell Labs to create the first commercially viable silicon solar cell.[3] In 1957, Mohamed M. Atalla developed the process of silicon surface passivation by thermal oxidation at Bell Labs.[8][9] The surface passivation process has since been critical to solar cell efficiency.[10]

Applications

There are many practical applications for the use of solar panels or photovoltaics. It can first be used in agriculture as a power source for irrigation. In health care solar panels can be used to refrigerate medical supplies. It can also be used for infrastructure. PV modules are used in photovoltaic systems and include a large variety of electric devices:

See also

  • Battery (electricity)
  • Daisy chain (electrical engineering)
  • Digital modeling and fabrication
  • Domestic energy consumption
  • Grid-tied electrical system
  • Growth of photovoltaics
  • List of photovoltaics companies
  • MC4 connector
  • Powerbank
  • Rooftop photovoltaic power station
  • Sky footage
  • SolarCity
  • Solar charger
  • Solar cooker
  • Solar oven
  • Solar roadway
  • Solar still

References

  1. ↑ Li, Wei; Rubin, Tzameret H; Onyina, Paul A (2013). "Comparing Solar Water Heater Popularization Policies in China, Israel and Australia: The Roles of Governments in Adopting Green Innovations". Sustainable Development. 21 (3): 160–70. doi:10.1002/sd.1547.
  2. ↑ "Metal Stamped Parts for Solar Paneling | American Industrial" (in en-US). American Industrial. https://www.americanindust.com/solar-panel-metal-stamping. 
  3. ↑ 3.0 3.1 3.2 "April 25, 1954: Bell Labs Demonstrates the First Practical Silicon Solar Cell". APS News. American Physical Society. 18 (4). April 2009.
  4. ↑ Christian, M. "The history of the invention of the solar panel summary". Engergymatters.com. Energymatters.com. Retrieved 25 January 2019.
  5. ↑ Adams, William Grylls; Day, R. E. (1 January 1877). "IX. The action of light on selenium". Philosophical Transactions of the Royal Society of London. 167: 313–316. doi:10.1098/rstl.1877.0009. ISSN 0261-0523. Retrieved 7 September 2018.
  6. ↑ Meyers, Glenn (31 December 2014). "Photovoltaic Dreaming 1875--1905: First Attempts At Commercializing PV". cleantechnica.com. CleanTechnica (Sustainable Enterprises Media Inc.). https://cleantechnica.com/2014/12/31/photovoltaic-dreaming-first-attempts-commercializing-pv/. Retrieved 7 September 2018. 
  7. ↑ Ohl, Russell (27 May 1941). "Light-sensitive electric device". Google. Retrieved 7 September 2018.
  8. ↑ Black, Lachlan E. (2016). New Perspectives on Surface Passivation: Understanding the Si-Al2O3 Interface (PDF). Springer. p. 13. ISBN 9783319325217.
  9. ↑ Lojek, Bo (2007). History of Semiconductor Engineering. Springer Science & Business Media. pp. 120 & 321-323. ISBN 9783540342588.
  10. ↑ Black, Lachlan E. (2016). New Perspectives on Surface Passivation: Understanding the Si-Al2O3 Interface (PDF). Springer. ISBN 9783319325217.