Where Is Solar Energy Found?
Solar energy refers to the radiant light and heat from the sun that can be harnessed using various technologies like solar photovoltaics and solar thermal collectors. Interest and investment in solar power has been rising globally due to its renewable, clean energy properties and rapidly declining costs. The growth rate of global solar energy capacity has been increasing at an average of 20% to 30% per year over the past decade, and solar power is seen as a key solution for transitioning away from fossil fuels and towards sustainable energy (source). This article will provide an overview of where solar energy is found and how it is harnessed around the world.
The Sun
The sun produces solar energy through the process of nuclear fusion, in which hydrogen atoms fuse together to form helium. This fusion reaction releases enormous amounts of energy in the form of solar radiation. The sun converts over 600 million tons of hydrogen into helium every second, releasing 3.8 x 10^26 joules of energy per second in the process (Source).
Some of this solar radiation continuously reaches the Earth in the form of solar irradiance. While the sun emits energy equally in all directions, only a tiny fraction of it reaches Earth. This is because the sun is approximately 150 million kilometers away from our planet. On average, Earth intercepts only one two-billionth of the sun’s total radiation output. The amount of solar energy striking the Earth’s atmosphere is about 1,366 watts per square meter on a surface perpendicular to the sun’s rays. This value is known as the solar constant. After passing through the atmosphere, approximately 1,000 watts per square meter reaches Earth’s surface on a clear day with the sun directly overhead (Source).
Solar Technology
There are several technologies that are used to convert solar energy into electricity or heat. The most common types are photovoltaics (PV), solar heating & cooling (SHC) technologies, and concentrated solar power (CSP).
Solar PV systems use solar panels containing solar cells to convert sunlight directly into electricity via the photovoltaic effect. Solar PV panels can be installed on rooftops or ground-mounted to generate electricity. Some key components of a solar PV system include PV modules/panels, inverters, racking and mounting structures, and other electrical accessories.
Solar heating and cooling (SHC) technologies harvest heat from the sun to provide hot water, space heating, cooling, and pool heating. Some examples of SHC technologies include solar water heating systems, solar air heating collectors, and solar absorption cooling systems. These systems reduce the need for electricity or gas to power water heaters, space heaters, and air conditioning.
Concentrated solar power (CSP) systems use mirrors to focus large areas of sunlight onto receivers that collect and convert the heat into electricity. CSP requires direct insolation to operate, and is ideal for utility-scale generation in sunny, arid locations. There are four types of CSP technologies: parabolic trough, linear Fresnel reflector, power tower/central receiver, and parabolic dish systems.
Overall, these solar technologies provide clean renewable energy from the abundant resource of solar irradiance. Solar PV and SHC are widely used today in distributed applications, while CSP has seen growth in large-scale solar power plants. Advances continue to improve efficiency and reduce costs.[1]
Ideal Conditions for Solar Energy
The most important factor in ideal conditions for solar energy is sunlight. Areas that receive abundant, consistent sunlight throughout the year are best suited for solar power. According to Energy5, the sunniest spots on Earth are along the equator where sunlight is most direct. Regions like the American Southwest, Northern Africa, the Middle East, and Australia have ideal conditions for solar due to high amounts of sunlight. Energy5 notes that the sunniest cities in the world can receive over 90% of possible sunshine.
Latitude plays a key role, as locations closer to the equator receive more consistent sunlight throughout the year. The farther from the equator, the less sunlight reaches the Earth’s surface at an optimal angle. Climate is also a factor, as cloudy or stormy regions will absorb less solar radiation. Hot, arid areas provide maximum sunlight exposure. For residential or commercial solar installations, south-facing rooftops receive the most sunlight in the Northern Hemisphere.
Overall, the ideal conditions for harnessing solar power are regions situated close to the equator that receive abundant sunshine throughout the year without excessive cloud cover or precipitation. Direct sun exposure translates into more incoming solar radiation to convert into renewable energy.
Leading Countries
China is currently the leading country for solar power capacity, accounting for nearly 40% of total global installed solar capacity as of 2022. China has around 390 GW of solar power installed, far surpassing any other country (Solar power by country). The rapid growth of solar in China has been driven by favorable policies and the large-scale solar farms deployed in the desert regions of the country.
The United States ranks second globally with around 130 GW of installed solar capacity as of 2022, providing about 3% of the country’s electricity. Major growth regions in the US include California, the Southwest, and parts of the Southeast (The Top 5 Solar Countries in the World). Residential and commercial rooftop solar has expanded significantly as costs have declined.
Japan, Germany, and India round out the top five countries for total installed solar capacity. However, on a per capita basis, countries like Australia, Italy, and Belgium lead for share of solar energy in their national energy mixes (Top Five Nations in Solar Energy Generation).
Rural/Off-Grid Use
Solar energy provides a sustainable and cost-effective solution for electrifying rural areas that lack access to traditional grid infrastructure. Off-grid solar systems like solar home systems, solar lanterns, and solar mini-grids allow remote communities to harness the power of the sun. According to the IEA, decentralized solar solutions have brought electricity access to over 28 million people in developing countries, with the numbers increasing every year (Challenges of Scaling Solar Energy in Rural Electrification Programs).
Solar power is ideal for rural electrification because it does not require fuel or extensive distribution infrastructure like traditional grids. Solar panels can provide electricity on-site, and excess power can be stored in batteries for use at night. This makes solar energy a practical and affordable way to meet basic electricity needs like lighting, phone charging, appliances, and powering healthcare clinics or schools in off-grid areas (Optimization of Solar System for Rural Electrification in Asia). With decentralized solar, rural communities can leapfrog fossil fuel-based energy systems and gain access to reliable electricity to improve quality of life.
Residential Rooftop Solar
Solar technology and net metering policies have allowed residential rooftop solar to become extremely popular in the United States. The solar power capacity across American homes increased dramatically from just 625 megawatts in 2010 to over 29.3 gigawatts in 2022 according to Statista. Forecasts predict continued strong growth, with residential solar PV capacity expected to reach over 100 gigawatts by 2030 and 263 gigawatts by 2050.
Net metering policies, which allow homeowners with solar panels to sell excess electricity back to the grid, have been a major driver of rooftop solar adoption. As of 2020, 40 states had mandatory net metering rules. This makes installing solar panels an attractive investment for homeowners in many parts of the country. Some utilities have pushed back against net metering, concerned about losing revenue, but most states continue to support it as a renewable energy policy.
With rapidly falling prices for solar panels and batteries, rooftop solar is becoming affordable for more American households each year. Government tax credits and solar leasing options also help reduce upfront costs. As rooftop solar expands, it will play a major role in the growth of renewable energy nationwide while giving households a chance to generate their own clean electricity.
Large-Scale Solar Farms
Some of the largest solar energy projects in the world are large-scale solar farms, also known as utility-scale solar installations. These massive solar photovoltaic power stations generate electricity that is fed into the electric grid to supply energy to entire regions. According to the Solar Energy Industries Association, utility-scale solar accounted for over 40% of total solar capacity in the United States in 2021.
The largest solar farm in the world is the Bhadla Solar Park in India, which spans over 14,000 acres and has an operational capacity of 2,245 MW, enough to power over 360,000 homes. It is part of India’s ambitious target of reaching 100 GW of solar capacity by 2022 (source). Other leading utility-scale solar farms include the 2,000 MW Huanghe Hydropower Hainan Solar Park in China and the 1,547 MW Tengger Desert Solar Park, also in China.
Some key benefits of building massive solar farms include economies of scale resulting in lower costs per watt, ability to locate in optimal high solar irradiation regions like deserts, and the flexibility to distribute solar energy across wider geographic areas. However, large solar farms also face challenges like land usage, grid integration, and variability. Overall, utility-scale installations will continue to play a major role in the growth of solar energy worldwide.
Future Outlook
The future projections for solar energy growth are very promising. According to Grandell (2016), “solar energy future projections presented in the IPCC Fifth Assessment Report do not seem to be realizable with the currently known technologies and feasible timescale.” However, the costs of solar have declined rapidly in the past decade, making the IPCC projections more achievable. The cost of solar panels declined by 90% between 2009 and 2020 (Grandell, 2016). Further cost declines are expected, driven by technology improvements and economies of scale as the solar industry continues to grow. Many projections estimate solar energy could supply up to 30-50% of global electricity by 2050.
Solar power capacity grew at an annual average of 49% between 2010-2019, and an estimated 115 GW was added globally in 2020 alone (Simmons, 2020). With continued policy support, declining costs, and increased energy storage, solar has potential for exponential growth in the coming decades.
Conclusion
Solar energy has incredible potential to provide clean, renewable power around the world. The sun bathes Earth in more energy than we can possibly use. The challenge is harnessing that energy efficiently and making solar technology affordable and accessible.
Solar power generation has grown exponentially in recent years thanks to improving technology and falling costs. Many countries are ramping up solar farms and rooftop installations to meet emissions targets and energy demands. Off-grid solar solutions are also bringing electricity to rural communities for the first time.
While solar currently provides a small fraction of global electricity, costs are projected to fall further as technology improves. With smart policies, declining prices and advances in energy storage, the future is bright for solar to supply an ever greater share of the world’s energy needs in a sustainable manner.
