Space Zoo Patrol – Photovoltaics

By Scott Sklar,  Adjunct Professor & Sustainable Energy Director, Environment & Energy Management Institute (EEMI) and Director, GWU Solar Institute, The George Washington University (GWU, and former Executive Director, Solar Energy Industries Association (SEIA) 

Background

  1. What is this technology called?

Energy from the sun can be categorized in two ways:

1) in the form of heat (or thermal energy) (discussed in a separate section), and 2) in the form of light energy (discussed here).

Technically solar electricity is called “Photovoltaics” (in ancient Greek photo means light, and voltaics means electricity).

  1. How does it work?

Photovoltaic cells (solar cells), convert the light of the sun directly into electricity. Solar cells are made of semiconductor materials, usually silicon, and other materials, that allows them to absorb photons from sunlight and release electrons. The electrons are attracted to the metal wires embedded in the panel and an electric current is produced which then flows along the wires out of the panel directly into an electrical product (like a lightbulb or a motor) or into a battery.

For increased electrical energy solar cells are connected together to form a photovoltaic module (panel) packaged with a transparent cover such as glass or plastic, and encased in a water-tight seal to protect it from the weather. Depending on the electrical need, several panels may be wired together to form an array.

A photovoltaic array, a group of solar modules produce electricity. A complete photovoltaic system consists of the module or array plus a number of other components. These additional components are known as the balance of system or BOS. The BOS components vary depending on what type of system is being powered and when it is needed. The panels are direct current (DC). However, most appliances found in a home use alternating current (AC), and thus AC is the current found in building and home wall sockets. Inverters, another component of the BOS, are used to transform DC electricity to AC. Photovoltaics can either be used immediately or stored in a battery (another BOS component), for later use.

PV panels/modules are very versatile and can be mounted in a variety of sizes and applications. PV panels may be placed on posts in the ground, attached to a roof, or integrated into building materials (such as PV shingles, which replace conventional roofing shingles).

PV uses no moving parts, consumes no fuel, and creates no pollution.

  • Who invented it? And when and where?

Photovoltaic (PV) systems were first invented in 1954 by the scientists at Bell Labs. In the 1960s, research was accelerated for the NASA space program and accelerated again in 1973, the year of the first oil embargo. Currently, the US DOE Renewable Energy Labs continues to make improvements.

 

  1. Advantages

Enough sunlight reaches the earth’s surface each year to produce approximately 1,000 times the same amount of energy produced by burning all fossil fuels mined and extracted during the same time period. Sunlight does not have to be explored, extracted, transported, combusted, create noise or pollution, or use precious fresh water.

  • What are the environmental advantages?

“The extraction, conversion, and utilization of energy is the single largest component of air and water pollution, as well as emissions causing the change of our global climate.”  – Christine A. Ervin, Assistant Secretary, Energy Efficiency and Renewable Energy (Department of Energy), 1997

Doctors attribute 50,000 American deaths per year to airborne particulate matter, about one-third of which comes from coal fired powerplants.

Solar energy is the pollution solution – it requires no fresh water, has close to zero air and water pollution emissions, and zero noise pollution. And solar panels may be recycled.

  • What are the life cycle financial advantages?

With an existing home, farm, or business, electrical system that is already grid connected, consumers don’t pay any initial (up-front) costs, but simply pay a monthly bill based on their electrical usage.  Installing a solar system now are financed by companies as power purchase agreements or leases, where the monthly costs are less than what you pay your local electricity for the same amount of electricity. If the consumer purchases a solar system outright, costs of savings over the life of the PV system end up saving much more than the initial cost.

Assuming a large roof with good solar orientation, a PV system is installed on a building (with enough panels) can zero out midday electricity costs and with battery banks can zero out any electric utility costs.

What are other additional advantages?

Simplicity – PV systems create electricity directly from sunlight. They come prepackaged, ready to be mounted and wired. Modules contain no moving parts, eliminating service and maintenance needs.

Versatility – PV systems come in a range of sizes and output. They are lightweight, allowing for easy and safe transportation in any terrain.

Modularity – New modules can be easily added to existing systems to expand with power needs.

Durability – PV systems are manufactured to withstand the most rugged conditions. Modules are designed to endure extreme temperatures, at any elevation, in high winds, and with any degree of moisture or salt in the atmosphere.

Reliability – Not only do PV systems perform in almost any environment, they are built and guaranteed to last 20 to 25 years or more. The service and maintenance costs incurred over the life of the system are far lower than conventional energy alternatives. In addition, if the local grid is down due to a storm, a building PV system with a battery bank will still be generating electricity allowing use of the refrigerator, lights, TVs, and computers.

    • What jobs are created?
    • Jun 30, 2021 As companies seek to reduce their dependence on foreign oil, nearly 304,000 people now work in the solarindustry. Solar jobs tripled from 2006 to 2014, there are now more solar workers than in oil and gas extraction.
  • These jobs are and will be in research, design, manufacturing, management, sales, service, and installation. These jobs will be both in the US and international.
  • https://www.gsesinternational.com/an-overview-of-the-solar-energy-jobs-in-the-us/
  1. Energy Production
    • How efficient is this technology?

The first PV cell at Bell Labs had about 6% efficiency.  In 1994 ECD had a breakthrough at 10%. Today PV cells range from 24 to 28%

    • How many units are needed for 1 house, 1 school, 1 community?

Watches and personal calculators can use one cell. A house may use approximately 5 to 20 modules. A community may use an array made of hundreds or thousands of modules.

    • What percentage of total energy usage (US) does this technology provide today?

As of 2022, PV provides about 2% of the electricity to the grid. (US EIA) But in terms of new electricity added to the US utility grid every year, since 2017 solar and wind provided the majority of new electricity generation added. In 2022, we expect 46.1 gigawatts (GW) of new utility-scale electric generating capacity to be added to the U.S. power grid, according to our Preliminary Monthly Electric Generator Inventory. Almost half of the planned 2022 capacity additions are solar, followed by natural gas at 21% and wind at 17%. https://www.eia.gov/todayinenergy/detail.php?id=50818

    • What percentage of total energy usage (US) could this technology provide in the future?

Theoretically, in conjunction with batteries, PV could provide 100% of the energy needed in the US. Most studies show solar photovoltaics eventually around 25% of US electricity.

    • What geographical areas can this be used in?

PV panels will work wherever there is sunlight. However, the more sun the better. So, while PV panels are used in Alaska, they are more effective in states with more direct sunlight (closer to the equator) such as California, Nevada, Arizona,  and Florida.

 

  1. Engineering
    • How is it manufactured?

The main resource required for many PV modules is silicon (a refined form of sand), the same material used in microchips. Various chemicals are then added (each company has their own secret recipe). Once the material has been melted into sheets, rows of wire are then added.  Sunlight (photons) hitting the now hardened panels creates electricity which then flows into the wires and out of the panels and into a battery for storage.  Initially this process was done by hand. It is now made on an assembly line at a factory.

    • What maintenance is required?

There are no moving parts in a PV system, so maintenance is minimal. Periodic review of wiring connections is helpful. Typically, PV panels get a light covering of dust or pollen which keeps sunlight from hitting the panels completely. Rain  or pressure-washing or wipers or brushes can be used to periodically clean the PV panels.

Education

    • What classes should I take in school to work on this technology?

Every field has applications to clean energy – sciences, engineering, business, land use planning, environmental science, architecture, sales, technical servicing, etc.

  1. Pictures

 

  • Photovoltaics 1

    Photovoltaic Sizes

  • Photovoltaics 2

    Components of PV system

  • Photovoltaics 3

    PV modules for a water pump on a farm

  • Photovoltaics 4

    PV array for a community

  • Photovoltaics 5

    PV array for a house

  • Photovoltaics 6

    PV array for the International Space Station

  1. Links

US Dept. of Energy                                             www.energy.gov/eere

Solar Energy Industries Association                    www.seia.org

American Council on Renewable Energy            www.acore.org

US Clean Power Association                               www.cleanpower.org