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Describe the effects of the use of solar energy in power generation on the environment.

Solar Energy

a tranquil scene featuring a person silhouetted against a radiant golden sunset. — **Solar energy is non-depletable AND renewable.**

Energy from the Sun has been used by humans for thousands of years to provide heat and to dry different kinds of food for preservation.

More recently, humans have found ways to gather and use the heat from the Sun in other ways and to produce electricity from sunlight.

The solar constant is 1,366 Watts/m². This means that 40 minutes of sunlight striking the United States could yield the equivalent of a year’s worth of fossil fuels. The Sun provides about 10,000 times the total energy used by humans.

And although the Sun is considered to be part-way through its life cycle, solar power is considered a renewable energy because if the Sun burns out all other forms of energy would be inconsequential as far as life on Earth goes.

Solar energy is expected to be at least a $20 billion industry. The solar energy market is growing by 40% per YEAR.

Explore the graph below. Do you have solar energy at your house? We are thinking about getting solar panels and battery backup at our house to heat the pool, house, and store energy for when the power goes out after storms.

Active Solar Systems

Flat-plate collectors are glass or clear plastic on top and have a black bottom. Water tubes are embedded between the clear top and black bottom. The sun heats up the water, and in active systems, the heated water is moved by a pump.

a 3D illustration of a solar panel’s cross-section. — **Solar systems can heat water for use in homes, buildings, or swimming pools and directly heat homes, greenhouses, and other buildings.**

an expansive view of a solar farm located in a desert area. — **Nellis AFB plans to double its solar capacity.**

In Nevada, Nellis Air Force Base built a 14-MW solar power plant and plans to double the capacity of its solar plant.

Some electric companies are also starting to build solar plants.

Essential Knowledge

Active solar energy systems use solar energy to heat a liquid through mechanical and electric equipment to collect and store the energy captured from the sun.

Photovoltaic Cells

Sunlight can be converted to electricity through photovoltaic cells (PV). Sunlight is composed of photons which are particles of solar energy. PV cells, which are composed of semiconductor material such as silicon, absorb photons and create a flow of electrons along the top surface of the PV cells.

A house with a grey roof, adorned with solar panels. A small black device is connected to the panels, and a potted plant sits beside the house. An oversized light bulb floats above, symbolizing energy production. — **PV cells harness energy from the sun and convert it to electricity.**

These electrons create an imbalance of electrical charge which, in turn, creates a voltage potential similar to that which exists between the positive and negative terminals of a battery. This potential can then be turned into an electrical current as shown in the image below:

The conversion of light energy into electrical energy within a solar cell. — **PV cells create an imbalance of electrons, which causes an electrical charge.**

New PV cells are known as SLIVERs. They are very thin and use 1/10 the silicon required in traditional PV cells. They are glass coated with light-absorbing dyes. Some solar plants have what is known as a solar trough, long, trough-shaped reflectors tilted toward the sun.

The sun is then reflected onto a pipe running through the middle of the trough. Dish-engine solar cells are a set of parabolic dishes that focus sunlight onto a receiver. These solar cells are 30% efficient, so they are overall, more efficient than traditional solar cells.

Essential Knowledge

Photovoltaic solar cells capture light energy from the sun and transform it directly into electrical energy. Their use is limited by the availability of sunlight.

Passive Solar Systems

Humans can also build passive solar homes. These homes have windows facing the Sun to heat the house in the winter and then drapes or shades trap the heat in the house at night.

These houses require good insulation to keep the solar heat from escaping. In the summer, an awning or overhang can shield the window from high summer sun, so the house is kept cooler in the summer.

On the left, under the title “Summer Sun,” the sun is shown high in the sky, with its rays being blocked by the house’s roof to keep the heat out. On the right, titled “Winter Sun,” the sun is depicted lower in the sky, with its rays entering through the windows to warm the house. The central title bridges both scenarios, emphasizing the design’s adaptability to seasonal changes. — **A passive solar home.**

a whimsical underground house reminiscent of a hobbit home. — **Hobbits live in earth-sheltered houses.**

Earth-sheltered houses are similar to Hobbit houses. They use dirt or soil as insulation and the windows are oriented toward the sun to capture the sun’s heat energy to heat the house. Passive solar houses that are well designed can reduce energy bills substantially with only a 5-10% increase in construction costs.

Concentrating solar collectors are used to concentrate the sun’s energy into a specific spot. These collectors move during the day to follow the strongest rays of sunlight. Plants using this technology can provide large amounts of electricity for customers or provide significant amounts of heat that can be used in industrial processes.

Essential Knowledge

Passive solar energy systems absorb heat directly from the sun without the use of mechanical and electric equipment, and energy cannot be collected or stored.

Environmental Effects of Solar Energy

Solar energy also still requires a backup energy source and a storage battery.

The main advantages of solar energy are two-fold:

✅ Does not produce air pollution or carbon dioxide

✅ When placed on buildings, solar energy systems have minimal effects on the environment.

✅ Solar cells can become operational within months, and it is easy to add capacity to a solar plant – just add another solar cell.

✅ Invulnerable to terrorist attacks

✅ Does not produce any hazardous waste

✅ 70% of our energy demand is during the day (people do not use a lot of energy when they are sleeping)

There are some significant disadvantages to solar energy, however:

❌ Amount and location of solar energy are not equal in all locations

❌ Difficult to store for use during nighttime

❌ Large farms in the desert may negatively impact desert ecosystems

❌ Requires a large amount of land if not installed on buildings

❌ Requires a backup energy source and a storage battery

❌ Photovoltaic cells (PV) are approximately 15-30% efficient

❌ Solar energy costs about $0.26 per kilowatt-hour, whereas traditional electricity costs approximately $0.06-0.12 per kilowatt-hour

The price point of PV cells continues to drop, however, as technology and production capabilities improve, as seen in the graph below:

If you live in a particularly sunny location, however, you can actually sell your excess solar-generated power back to the power company and receive a credit on your power bill, which offsets some of the cost of the solar energy system.

Essential Knowledge

Solar energy systems have low environmental impact and produce clean energy, but they can be expensive. Large solar energy farms may negatively impact desert ecosystems.

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