Harnessing the Sun: A Comprehensive Guide to Solar Energy
Sun Energy
0. Introduction
History:
The use of solar energy dates back to the times of Archimedes, who, according to legend, used mirrors to reflect sunlight onto Roman ships, setting them ablaze.
In 1839, Edmond Becquerel discovered the photovoltaic effect at the age of 19. He observed that certain materials produced small amounts of electricity when exposed to sunlight.
Later, in the 1870s, Heinrich Hertz studied the effects of sunlight on solids and became the first to discover the ability of solar cells to transform sunlight into electricity.
In 1883, Charles Fritts constructed the first solar cell using selenium and gold.
The modern era of photovoltaic technology began in 1954 when Bell Laboratories discovered that selenium with impurities was highly sensitive to sunlight.
Industrial production of solar cells commenced in the 1980s.
Types:
There are two main types of solar energy:
Thermal:
This mechanism converts sunlight into heat, commonly used in homes for heating. These systems absorb sunlight through coatings, which can be paint or selective surfaces. The absorbed solar energy is then transferred to a heat-carrying fluid within collector tubes, forming the solar or primary circuit.
Photovoltaic:
This type relies on the photovoltaic effect, which transforms solar energy into electrical energy using solar cells.
This transformation occurs without moving parts, thermodynamic processes, or chemical reactions.
Solar cells are connected in series on solar panels to achieve a suitable voltage and are typically oriented south for optimal energy capture.
Currently, this type of solar energy is used for:
- Subsistence: Providing power to individual homes.
- Integration into the electrical grid.
1. Theoretical Bases
Solar cells depend on the photovoltaic effect, where solar energy generates positive and negative charges in two adjacent semiconductors of different types, creating an electric field that generates a current.
When sunlight strikes a solar cell, photons transfer their energy to the electrons in the semiconductors, causing them to be released and generate an electrical current that can be harnessed by an external circuit.
This system is utilized in solar-powered electric vehicles and solar ships.
2. Advantages
Thermal:
- Inexhaustible resource.
- Promotes sustainable development.
- Non-polluting.
- More cost-effective than water and electricity.
- Its growth creates jobs.
- Integration of rural areas.
- Does not degrade air and soil quality.
- Increases property value.
- Contributes to environmental protection.
- Can be installed quickly.
Photovoltaic:
- Non-polluting.
- Does not require fuel.
- Does not generate waste.
- Silent operation.
- Inexhaustible resource.
- Simple installation.
- Long lifespan (30 years).
- Resistant to extreme weather.
- Can be used in areas without electricity.
- Scalable power output.
3. Disadvantages of Solar Energy
Thermal:
- Solar radiation levels vary by location and season.
- Large land areas are required for significant electricity generation.
- High initial investment.
- Areas with high solar radiation are often deserts.
- Requires the absence of pollutants.
Photovoltaic:
- Visual impact of solar parks.
- Only produces energy in the presence of sunlight.
- High cost.
- Relatively short lifespan (10 years).
- Low efficiency (around 20%).
- No energy production at night.
4. Environmental Impact
The most significant environmental impact of solar energy is on the landscape, particularly when solar plants are installed in rural or natural areas. Proper site selection is crucial to minimize this impact and maintain harmony with the environment.
Careful consideration of location is the primary way to mitigate landscape impact. Corrective measures, such as choosing appropriate materials and colors for posts, can further reduce the visual impact.
Land use by solar parks is permanent during their operational lifespan. Environmental studies should be conducted to assess energy production and potential ecological consequences.
Soil pollution during construction can be minimized with proper precautions. Avoiding the placement of solar parks in natural areas and conducting vegetation studies are essential, especially in areas with protected species.
Solar parks can disrupt food chains and ecosystems, particularly affecting species that nest on dry surfaces, which are often chosen for solar park installations.
5. Cost
Solar Energy and Cost-Competitiveness
Solar energy currently represents a small fraction of total energy generation and consumption. To increase its market share, it must become cost-competitive with other major energy sources. Achieving this depends on policy incentives that reduce the overall costs of solar technologies and continued high prices for conventional electricity generation. However, solar has already achieved competitiveness in some market segments.
Solar Energy Cost
Installing a solar electric system can lead to cost savings, independence from utility companies, and environmental benefits.
Just 20 years ago, solar energy cost seven times more than it does today. Technological advancements have contributed to this significant price reduction, but the primary driver has been the increase in manufacturing volumes as more people recognize the advantages of solar energy.
Just How Much Does Solar Energy Cost?
The positive trend continues. Solar energy costs are projected to decline further as the market expands, making it even more affordable.
As a general estimate, depending on specific conditions:
- A solar hot water system will cost between US $2,000 and $4,000.
- A photovoltaic system will cost between US $8,000 and $10,000 for a 1kW system (or $8-$10/Watt).