How Solar Works

A building

When talking about solar, everyone tends to understand the basics which is that solar panels collect energy from the sun and that energy is used to power your home. But what exactly is solar energy and how is it made? This simple question has a pretty complicated answer. In this article, we are going to break it down for you.

The main component of a solar panel is a solar cell, also known as a photovoltaic cell (PV), which converts sunlight into electrical energy.  Sunlight is composed of photons, which contain varying amounts of energy (2). PV cells are made of semiconductor materials containing a P-type silicon layer and an N-type silicon layer. The P-type layer has a deficit of electrons and is produced by adding atoms such as boron or gallium, which have one less electron in their outer energy level (3, 4). The N-type layer is made by including atoms that have more electrons in their outer level such as phosphorus. These two layers are then placed next to each other, the N-type has an excess of electrons, and the P-type has an excess of positively charged holes. The electrons from the N-type layer move into the holes in the P-type layer, which then creates an area around the junction called the depletion zone. When the sunlight hits the cell, the electrons from the N-type layer flow towards the P-type layer. These moving electrons create a flow of electricity that can be harnessed to power an electrical device (5).  

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Representation of a solar cell | source: solar cell

A PV cell typically produces about 3-4 watts of power. For cells to withstand being outdoors they are sandwiched between protective materials in combination with glass and/or plastics (4). The PV cells are then connected in chains to form larger units known as panels or modules. Multiple modules are then connected to form arrays. One or more arrays are then connected to the electrical grid as part of a complete PV system. A sufficiently sized system can meet almost any electric power need, small or large. The PV modules/arrays are just one part of the system. Important components also include mounting structures, inverters, cabling, electrical equipment, distribution equipment, the electrical meter, and the electrical grid (2).

A mounting structure provides stable and durable support that withstands wind, rain, hail, and corrosion. To obtain the highest energy output, the system is pointed towards the south (in the Northern Hemisphere, at least). Rack mounting is the most common method since it is versatile and easy to construct and install (6).

Inverters are used to convert the direct current (DC) electricity that is generated by the PV modules into alternating current (AC) electricity. Click over to read our article on DC to AC. Each system either has one inverter that converts the electricity generated by all the modules, or the system has microinverters that are attached to each module. The microinverter allows for independent operation of each panel which is beneficial if modules are shaded. Advanced inverters allow for two-way communication between the inverter and the electrical utility. Having this insight helps to reduce costs, ensure grid stability, and reduce power outages (6).

This converted current travels from the inverter to the existing main electric panel which then distributes the electricity throughout the house. If the system is connected to the grid, any unused electricity passes through the home’s electric meter and is given to the utility grid. The homeowner can then receive credit for this excess electricity. To learn more about receiving credit for your excess electricity, click over and read our blog on solar renewable energy credits.

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How Solar Panels Work | source: solar panel

References:  

  1. https://www.energy.gov/eere/solar/how-does-solar-work
  2. https://re-volv.org/get-involved/education/solarenergy/?gclid=Cj0KCQiA1rSsBhDHARIsANB4EJblzBB3d59bqZw6LyRaG7rqObnuVE7KBeZbSh13tFRb_KQYqDdlODQaAr89EALw_wcB
  3. https://www.acs.org/education/resources/highschool/chemmatters/past-issues/archive-2013-2014/how-a-solar-cell-works.html
  4. https://www.britannica.com/technology/solar-panel
  5. https://energy5.com/breaking-down-the-chemistry-of-solar-energy-how-photovoltaic-cells-create-electricity
  6. https://www.energy.gov/eere/solar/solar-photovoltaic-system-design-basics
  7. https://www.energy.gov/eere/solar/solar-photovoltaic-technology-basics

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