How Does Solar Power Work?

When you think of the sun, what comes to mind? Do you think about how it signals the start and end of each day? Does it make you think about vacationing by a beach or hiking in the mountains? Maybe you think about how the earth has been orbiting this same sun since the beginning of time.

Solar Module

What you probably don’t think about, however, is that this massive star produces enough energy to power 2,800 trillion light bulbs per hour. That’s the equivalent of giving all 7 billion people on this planet a light bulb that will burn brightly for their entire lifetime.

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A Brief History of Solar Power

In 1954, three scientists at the Bell Laboratory decided to capitalize on the sun’s incredible ability to produce energy and use it as a means of providing electricity. The trio patented silicon-based solar cells as a way to convert sunlight directly into electricity.

This primitive solar cell had about six-percent efficiency, meaning it could harness and convert six percent of the sun’s energy into electricity. Now, 62 years later, scientists have developed a new solar cell with a conversion efficiency of 40.7 percent. This milestone marks the achievement of a decades-long goal of breaking the 40 percent efficiency barrier and also opens the doors to entirely new levels of solar energy experimentation.

Thanks to massive technological advances like the recently developed photovoltaic (PV) cell, homeowners and businesses across the globe are turning to solar power as a means of having affordable, reliable electricity without depleting the earth’s finite amount of fossil fuels.  As the cost of solar panels plummets, global solar panel installations soar leaving many to wonder, just HOW does solar power work?

By taking a behind-the-scenes look into solar power, you can gain a deeper understanding of the complex solar-conversion process.

How It’s Made: Solar Modules 101

Completed Solar Panel

Solar modules, or panels, are comprised of dozens of individual cells. It is these cells that act as a semiconductor device to convert solar light energy into electrical energy. The making of solar modules can be broken down into 10 different steps.

  1. Extract impurities: First the module’s material – silicon dioxide – is placed into an electrical furnace where carbon arc is applied to extract the oxygen and produce a product with one-percent impurity.
  2. Purify again: Though many industries (besides solar) use silicon with one percent impurity, the solar industry demands 100-percent pure silicon. Thus, the 99 percent pure silicon is purified again using a unique heating technique that drags the silicon several times through a heated zone. This process forces the remaining impurities to a contained area at the end of the silicon rod which is then extracted.
  3. Make crystal silicon: Silicon boules, also known as silicon crystals, are made in a process called the Czochralski method, where a single, small crystal is submerged into a melted polycrystalline silicon liquid. As the single crystal is rotated and removed, a boule of pure silicon is formed and all impurities remain in the melted liquid.
  4. Cut wafers: Once the crystals are made, saws are used to cut them into thin, .5-millimeter-thick wafers. Most wafers are cut in the form of rectangles or hexagons because they can be assembled to utilize all of the space of the surface of the solar cell.
  5. Polish wafers: Wafers are polished to remove saw marks and prepare the surfaces to absorb light as effectively as possible.
  6. Adding impurities to wafers: Wafers are sealed together back-to-back and heated to around 2,570 degrees Fahrenheit – just below the melting point. When introduced to trace amounts of impurities like phosphorous gas, the porous state of the heated silicon allows phosphorous atoms to burrow into the wafer. This is a critical part of the process because it enables the release of the positive electron that later creates an electrical current.
  7. Place electrical contacts: Solar cells are connected to one another via thin electrical connections. These connections are made from metals like silver, nickel, or copper that are vacuum-evaporated and applied to an exposed portion of the cell.
  8. Connect cells: After electrical contacts are placed on each cell, the cells are then connected with thin strips of tin-coated copper, or “fingers.”
  9. Apply anti-reflective coating: Silicon is notoriously shiny and can reflect up to 35 percent of sunlight. Therefore, an anti-reflective coating is applied on the surface of each silicon wafer.
  10. Encapsulate the cell: Once wafers are treated with the anti-reflective coating, the cells are finalized by being sealed, or encapsulated, into silicon rubber or ethylene vinyl acetate, an elastomeric polymer with “rubber-like” qualities. The encapsulated cells are placed into an aluminum frame with a heat-resistant plastic backsheet and a clear glass or plastic cover. This final product is called a solar module or solar panel.

Finalized solar modules are connected with others to create what’s called an array of panels. When sunlight gets absorbed by the panels, one of the many electrons in the silicon bonds or electrical connections excites up to a high energy level that allows it to move much more freely than when it was bound. This electron can then move around the wafer freely which creates an electrical current.

 

When it comes time to install solar panels on a home or business, professional installers recommend that all panels in the Northern Hemisphere should face true south in order to capture the most sunlight possible and thus generate the most electricity.

Importance of the Inverter

Perhaps the most critical component of a solar panel system is a solar inverter. The inverter, also called “the brain,” is the actual device that converts the direct current (DC) from the solar panels into alternating current (AC) that can be used to power TVs, computers, and other wired products.

dc-ac inverter

After combining digital control technology with efficient power conversion architecture, the inverter has the ability to convert as much energy from the panels as possible. New to the solar industry are “smart inverters” that can be sent specific instructions like when to use PV (photovoltaic) energy, when to send power to batteries for storage, or when to convert and save power.

Measuring Energy with the Utility Meter

To best understand what the utility meter is and why it’s important, it’s helpful to revisit some of the key components that have been discussed thus far the solar conversion process.

  1. Solar panels are comprised of PV cells that convert sunlight into DC electricity throughout sunlight hours.
  2. Inverters convert the DC electricity into AC electricity and send it to an electrical panel which powers lights and appliances with solar energy. This electrical panel is also called a “breaker box.”

Electricity Utility Meter

The utility meter measures the amount of energy used every day and reverses when the system generates more power than initially needed. This excess energy offsets the energy you use at night.

Using a Utility Grid

There are two main types of solar panel systems: grid-connected and off-the-grid. Off-the-grid systems are used for small solar projects like cottages, RVs, and sheds. Grid-connected systems, on the other hand, are ideal for homeowners who want to power their entire home and benefit from Feed-in Tariffs, or payments to ordinary energy users for the renewable “green” electricity they create. Grid-connected systems are also beneficial for individuals who want to have access to electricity during both daylight and nighttime hours.

Power Line

A Review of How Solar Power Works

The most critical components of solar power are the solar cells, or PV cells, that make up the solar panels. Made of 100-percent pure silicon crystals, solar wafers are treated with trace amounts of phosphorous impurities that essentially enable the release of a positive, current-creating electron. Energy-conducting connectors are then applied to the wafers, which are arranged on a plastic backsheet and sealed with a protective glass lid to create a solar panel. These panels are treated with anti-reflective coating to better convert electricity and installed in an array on the south-facing side of the home or business owner’s roof.

Solar Power Basic Overview

When exposed to sunlight, the electron in the electrical bonds moves freely around the cell, creating a current. The current creates DC electricity that the inverter converts into the AC electricity that’s then sent to the electrical panel on the home to power lights and appliances. The utility meter measures how much of the electricity produced is actually used. Any excess solar energy is then stored for nighttime hours which grid-connected systems can use. For a simpler explanation on how solar power works, check out our Solar 101 page!

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