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Solar Power

The contribution of solar energy to the world’s energy supply has grown rapidly. This video shows how solar cells or photovoltaic cells produce electricity.

PERFORMANCE

There are two primary technologies that can harness the sun’s power and turn it into electricity. The first is photovoltaics, or PV for short. These are the panels you’ve seen on rooftops or in fields. When the sun shines onto a solar panel, photons from the sunlight are absorbed by the cells in the panel, which creates an electric field across the layers and causes electricity to flow. An individual PV cell is usually small, typically producing about 1 or 2 watts of power. To boost the power output of PV cells, they are connected together in chains to form larger units known as modules or panel arrays.

PV arrays must be mounted on a stable, durable structure that can support the array and withstand wind, rain, hail, and corrosion over decades. These structures tilt the PV array at a fixed angle determined by the local latitude, and electrical load requirements. To obtain the highest annual energy output, modules in the northern hemisphere are pointed due south and inclined at an angle equal to the local latitude. For PV arrays mounted on the ground, on the other hand, tracking mechanisms automatically move panels to follow the sun across the sky, which provides more energy and a higher return on investment (ROI). One-axis trackers are typically designed to track the sun from east to west. Two-axis trackers allow for modules to remain pointed directly at the sun throughout the day. Naturally, tracking involves more up-front costs and sophisticated systems are more expensive and require more maintenance.

Once the panels are installed, workers check the electrical systems for proper wiring, polarity, and grounding, and they also perform maintenance as needed. Photovoltaic arrays must be mounted at a fixed angle determined by the local latitude. Alternatively, automatic mechanisms may be installed to move panels to track the sun across the sky, which increases absorbtion of solar energy.

SOLAR DESIGN

Organic PV, or OPV, cells are composed of carbon-rich polymers and can be tailored to enhance a specific function of the cell, such as sensitivity to a certain type of light. This technology has the theoretical potential to provide electricity at a lower cost than silicon or thin-film technologies. Concentration PV, also known as CPV, focuses sunlight onto a solar cell by using a mirror or lens. By focusing sunlight onto a small area, less PV material is required. PV materials become more efficient at energy conversion as the light becomes more concentrated, so the highest overall efficiencies are obtained with CPV cells and modules. However, more expensive materials, manufacturing techniques, and tracking are required, so demonstrating the necessary cost advantage over today's high-volume silicon modules has become challenging. This technology uses mirrors to reflect and concentrate sunlight onto receivers that collect solar energy and convert it to heat, which can then be used to produce electricity.

Inverters are used to convert the direct current (DC) electricity generated by solar photovoltaic modules into alternating current (AC). PV systems either have one inverter that converts the electricity generated by all of the modules, or microinverters that are attached to each individual module. A single inverter is generally less expensive and can be more easily cooled and serviced when needed. By comparison, the microinverter allows for independent operation of each panel, which is useful if some modules might be shaded, for example. Finally, large batteries allow for the storage of solar photovoltaic energy when bad weather blocks sunlight from reaching the photovoltaic panels.

Passive solar design takes advantage of a building’s site, climate, and materials to minimize energy use. A well-designed passive solar home first reduces heating and cooling loads through energy-efficiency strategies and then meets those reduced loads in whole or part with solar energy. Because of the small heating loads of modern homes it is very important to avoid oversizing south-facing glass and ensure that south-facing glass is properly shaded to prevent overheating and increased cooling loads in the spring and fall. A passive solar home collects heat as the sun shines through south-facing windows and retains it in materials that store heat, known as thermal mass. The share of the home’s heating load that the passive solar design can meet is called the passive solar fraction, and depends on the area of glazing and the amount of thermal mass. The ideal ratio of thermal mass to glazing varies by climate. Well-designed passive solar homes also provide daylight all year and comfort during the cooling season through the use of night-time ventilation.

EDUCATION

PV installers learn their trade on the job by working with experienced installers. On-the-job training usually lasts up to a year, depending on the complexity of the system. During training, PV installers learn about safety, tools, and PV system installation techniques. Further, roofing apprentices and journey carpenters may complete photovoltaic-specific training modules through apprenticeships. Military veterans may benefit from the Solar Ready Vets program, which is an effort of the US Department of Energy to connect veterans with training and jobs in the solar industry.

Installers with knowledge of electrical work, such as licensed electricians, are highly valued by contractors. Certification can demonstrate a PV installer's competency in solar panel installation. The Electronics Technicians Association, International (ETA); the North American Board of Certified Energy Practitioners; and Roof Integrated Solar Energy (RISE) Inc., all offer certification for PV installers.

QUALITIES FOR SUCCESS

Ask yourself if you can see yourself being a solar installer or technician, working with technical concepts and complex equipment, which can be challenging. While classes and internships will prepare you well, certain innate qualities that you bring to bear will help you succeed.


Solar Power
Photo-voltaic installers often need to communicate effectively with clients to ensure customer satisfaction and with other workers to ensure that proper safety and installation procedures are followed.
PV installers must carefully follow instructions during installation. If they fail to do so, the system may not work properly.
Solar technicians work with complex electrical and mechanical equipment in order to build support structures for solar panels and to connect the panels to the electrical system.
When installing rooftop panels, workers may need to climb ladders many times throughout the day. In addition, installers are often on their feet carrying panels and other heavy equipment.
Physical strength may be required, as PV installers often lift heavy equipment and materials weighing up to 50 pounds.

Rooftop Solar Cells


Tesla unveiled its first ever solar products, a range of four solar roofing materials that look almost indistinguishable from high-end terracotta, slate, or asphalt shingles.

Future of Energy (China)


China, the world’s biggest polluter, has committed to reach net zero emissions by 2060, an ambitious goal matched by enormous investments that are reshaping the nation’s energy system.

Community Solar


A new business model for residential power enables people to switch to solar without the up-front cost of home installation, a critical step in bringing the green revolution to fruition.

Solar Panels


The Earth intercepts a lot of solar power: 173,000 terawatts. That’s 10,000 times more power than the planet’s population uses. So is it possible that one day the world could be completely reliant on solar energy? Richard Komp examines how solar panels convert solar energy to electrical energy.

INDUSTRY OUTLOOK

Employment of solar photovoltaic installers is projected to grow 95 percent to 2026, much faster than the average for all occupations. The continued expansion and adoption of solar panel installation is expected to create new jobs.

As the cost of PV solar panels continues to fall, more residential households are expected to take advantage of these energy systems, resulting in greater demand. Solar photovoltaic installers risk falls from ladders and roofs, shocks from electricity, and burns from hot equipment and materials while installing and maintaining PV systems.

  • The Global Off-Grid Lighting Association tracked 7.4 million off-grid solar products installed in 2021. They had a capacity of 69 megawatts (MW).
  • As of Q4 2021, the solar industry employed more than 255,000 workers.
  • The United States installed 4.3 gigawatts-AC (GWac) of photovoltaics (PV) in Q1 2022; ~45% of that was in Texas, Florida, and California.
  • The U.S. Energy Information Administration estimates solar will install almost 26 GWac in 2022 and 33 GWac in 2023, compared to 19 GWac in 2021.
  • 29% of U.S. utility-scale PV and ~19% of all U.S. PV systems built in 2021 used cadmium telluride (CdTe) panels.
  • The United States installed ~2.9 gigawatt-hours (GWh) (0.955 GWac) of energy storage onto the electric grid in Q1 2022.

SOLAR RESOURCES

The Office of Energy Efficiency and Renewable Energy (EERE) leads research in innovative technologies that will make renewable electricity generation cost competitive with fossil fuels. The Solar Energy Technologies Office (SETO) funds research and development across the solar energy spectrum to drive innovation, lower costs, and support the transition to a decarbonized power sector by 2035 and a decarbonized economy by 2050.

The International Renewable Energy Agency (IRENA) is an intergovernmental organization that promotes the widespread adoption and sustainable use of all forms of renewable energy, such as bioenergy, solar, wind, hydropower, and geothermal. With this, they aim to support countries in their transition to a sustainable energy future. Furthermore, they also serve as the principal platform for international cooperation and a repository of policy, technology, resource, and financial knowledge on renewable energy.


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