By
Grace Smoot

Enough sunlight strikes the surface of the earth in an hour and a half to account for the world’s energy consumption in a year. Solar energy has such a large electricity generation and climate mitigation potential. So, we had to ask: How does solar energy work?

Solar energy works by converting sunlight into electricity via photovoltaic (PV) solar cells or solar mirrors (CSP). PV solar cells create an electrical charge with sunlight that causes electricity to flow; CSP mirrors reflect and concentrate sunlight onto receivers that convert it into heat energy.

Keep reading to find out what solar energy is, how it works, how effective and efficient it is, how safe or dangerous it is, the pros and cons associated with it, and how it can be classified.

The Big Picture of Solar Energy Generation

Global population growth has increased our electricity generation from 66 terawatt-hours (TWh) in 1900 to over 29,000 TWh in 2022. The more people there are, the more electricity we need to generate to meet their needs.

“Electricity generation: electricity generated from fossil fuels, nuclear power plants, hydropower plants (excluding pumped storage), geothermal systems, solar panels, biofuels, wind, etc.”

Organization for Economic Co-operation and Development

Most of our electricity generation has traditionally come from the combustion of fossil fuels (e.g., coal, oil, natural gas). But as the current climate crisis continues to worsen, the focus has shifted towards increasing renewable energy capacity. One of our most advanced and widespread renewable energy technologies is solar energy. 

Solar energy is the conversion of solar radiation into electrical energy through photovoltaic (PV) panels or solar radiation-concentrating mirrors. The energy produced is then used to generate electricity or can be stored in batteries or thermal storage for use at a later time. 

“Solar Energy: energy that uses the power of the sun to produce electricity”

Cambridge Dictionary

Electricity generation in the 1900s mainly came from a mix of coal, oil, and natural gas. It wasn’t until the 2000s that concern over the growing climate crisis increased interest in renewable energy and more specifically in 2010 when there was a push to increase solar energy capacity worldwide.

Solar Energy Generation Steps	Summary
Step 1: The Origin of Sunlight	Sunlight is the result of a nuclear fusion reaction that takes place inside the sun’s innermost core. Hydrogen and helium fuse, releasing energy and light. This light takes 40,000 years to reach the surface of the sun and then 8.5 minutes to reach the Earth.
Step 2: Solar Energy Technologies	Harnessing the power of the sun falls into two main categories, photovoltaic (PV) solar cells and concentrating solar thermal plants (CSP).
Step 3: How Solar Energy Really Works	PV solar: Sunlight strikes a PV solar cell, creating an electrical charge. The charge moves in response to an internal electric field in the cell, causing electricity to flow. Concentrating solar: Mirrors reflect and concentrate sunlight onto receivers. Receivers collect and convert solar energy into heat.
Step 4: How Solar Energy Gets to the Grid	For both PV and concentrating solar energy, the electricity generated is either stored for later use or is transported to a substation where it is transmitted to consumers via transmission lines.

Step 1: The Origin of Sunlight

The sunlight we observe here on Earth is the result of a nuclear fusion reaction that takes place inside the sun. Nuclear fusion is the process by which lighter atoms are combined or fused to create larger and heavier atoms.

“Nuclear fusion: the process of joining two nuclei to produce energy.”

Cambridge Dictionary

Inside the sun’s innermost core, lighter hydrogen atoms fuse to form heavier helium atoms, a process that releases energy and light, in the form of photons. Those photons embark on a 40,000-year journey to the surface of the sun, where they are then emitted out into the solar system. It takes those photons approximately 8.5 minutes to travel the 93 million-mile distance from the sun to the Earth.

Step 2: Solar Energy Technologies 

Once sunlight reaches the earth, specialized technology can harness it and convert it into electricity. Harnessing the power of the sun falls into two main categories:

1. Photovoltaic (PV) solar cells: photovoltaic cells in solar panels absorb energy from sunlight, creating an electrical charge. 

2. Concentrating solar thermal plants (CSP): mirrors reflect and concentrate sunlight onto receivers that collect and convert solar energy into heat. This is utilized in very large power plants.

Both systems take the energy from the sun and convert it to electricity, just by slightly different mechanisms. PV solar is the main mechanism used today to harness solar energy.

Step 3: How Solar Energy Really Works

Solar energy operates differently depending on the type of solar power plant (e.g., PV or CSP).

PV solar power operates in the following way: 

1. Sunlight strikes a PV solar panel, creating an electrical charge.
2. The charge moves in response to an internal electric field in the cell, causing electricity to flow.
3. PV solar generates direct-current (DC) electricity, which must then be converted into alternating-current (AC) electricity, the type used to power household appliances.

Concentrating solar power (CSP) operates in the following way: 

1. Mirrors reflect and concentrate sunlight onto receivers.
2. Receivers collect and convert solar energy into heat.
3. In the case of linear and power tower systems, the heat boils water to produce steam. The steam then spins a turbine and powers a generator to produce electricity.
4. In the case of dish/engine systems, a heated receiver moves pistons in an engine. This movement powers a generator to produce electricity.

Step 4: How Solar Energy Gets to The Grid

For both PV and concentrating solar energy, the electricity generated is either stored for later use or is transported to a substation where it is transmitted to consumers via transmission lines. Transformers receive the electricity and either increase or decrease the voltage as needed before it can be delivered to consumers. 

How Effective and Efficient Is Solar Energy

In terms of effectiveness, solar panels and concentrating mirrors are effective ways to convert sunlight into electricity. In addition, solar energy has a low carbon footprint, protects air quality, and promotes energy security and independence.

In terms of efficiency, solar panels are efficient at converting sunlight into electricity. In addition, solar energy is a renewable and sustainable energy source, increases the efficiency of the power grid, and generates few waste products.

Solar energy is effective because:

• Solar energy is an effective way to convert sunlight into energy. It is currently our third-largest renewable electricity technology behind hydropower and wind energy.
• Solar has the fifth-lowest carbon footprint out of all energy types. Concentrating solar energy emits 38, PV roof solar energy emits 41, and PV utility solar energy emits 48 grams of CO₂ equivalent per kWh of electricity produced, on a life-cycle basis.
• Solar produces a fraction of the pollution and toxic chemicals that fossil fuels produce, helping to protect air quality.
• Solar can help us transition away from fossil fuels and towards an energy-independent future.

Solar energy is efficient because:

• Solar energy boasts a high rate of efficiency per solar panel (15-20%) and is an efficient use of farmland.
• Solar energy is a renewable and sustainable resource that can reduce emissions for generations to come.
• Solar energy promotes the decentralization of our energy supply which increases power grid efficiency by reducing peak time usage and decreasing the likelihood of power outages. 
• Solar energy generates few waste products upon operation, and solar panels can be recycled.

How Safe or Dangerous Is Solar Energy

Overall, solar energy is not considered to be dangerous. Holistically and throughout its life cycle, solar is safe and beneficial for human and animal health, the environment, and the energy grid. It is also significantly safer than fossil fuels and other types of renewable energy.

Here’s How Safe Solar Energy Is

Overall, solar energy is a safe form of energy regarding human and animal health, the environment, the energy grid, and throughout all stages of its life cycle.

How Safe Is Solar Energy at a Holistic Level	Human and Animal Health: Solar energy is safe for human and animal health and can be made safer with proper siting, monitoring, and maintenance of solar facilities.  Environment: Solar energy emits minimal greenhouse gas emissions and has a minimal effect on the environment. Energy Grid and Infrastructure: Solar energy is a safe and beneficial addition to our power grid. It promotes the decentralization of our energy supply, which increases power grid efficiency by reducing peak time usage and decreasing the likelihood of power outages.
How Safe Is Solar Energy Across Its Life-Cycle	Building: Safe work practices and proper training of solar professionals can mitigate any risks associated with constructing solar facilities. Operating and Maintaining: Solar energy is considered safe to operate and maintain because it does not harm human health or the environment when producing energy.  Building Back: This final stage is considered to be safe overall, with the most common workplace hazards (lifting, trips and falls, electricity, and ladders) able to be mitigated by safe work practices.
How Safe Is Solar Energy In Comparison to Other Types of Energy	Solar energy is one of our safest forms of energy that has one of the lowest death rates from accidents and air pollution per unit of electricity generation.

Here’s How Dangerous Solar Energy Is

Overall, solar energy is considered minimally dangerous in terms of human and animal health, the environment, the energy grid, and through all stages of its life cycle. 

How Dangerous Is Solar Energy at a Holistic Level	Human and Animal Health: Solar energy is not dangerous to humans and is minimally dangerous to animals, with the main concerns being habitat loss and fragmentation of natural habitats. Environment: Solar energy is minimally dangerous to the environment, with land degradation and solar panel toxicity being the two main concerns.  Energy Grid and Infrastructure: Solar energy is not considered to be dangerous to our energy grid or supporting infrastructure.
How Dangerous Is Solar Energy Across Its Life-Cycle	Building: Building solar facilities can expose workers to arc flashes (arc flash burn and blast hazards), electric shock, falls, and thermal burns. Operating and Maintaining: Solar energy has minimal dangers associated with this stage, with burns and electric shock being the most common. Building Back: The most common workplace hazards of this stage include those resulting from lifting, trips and falls, electricity, and ladders.
How Dangerous Is Solar Energy In Comparison to Other Types of Energy	Solar energy is significantly less dangerous than fossil fuels and other types of renewable energy. In fact, solar is one of the, if not the, safest forms of energy with a death rate of only 0.02 deaths per terawatt-hour of electricity produced.

What Are the 6 Pros and 4 Cons of Solar Energy

Solar energy is a renewable and sustainable energy source, has a low carbon footprint, protects air quality, is efficient, generates few waste products, has low maintenance costs, and promotes energy independence and security.

However, solar energy is also an intermittent energy source, faces high upfront and maintenance costs, and has specific land requirements.

These Are the 6 Pros of Solar Energy

Solar energy has various pros that make it effective at reducing carbon emissions.

6 Pros of Solar Energy	Quick Facts
#1: Solar energy is a renewable energy source	Solar energy is classified as a renewable energy source because the sun generates energy at a rate faster than we can consume it. It is also sustainable because it emits minimal greenhouse gas emissions (GHGs) and does not negatively affect the environment, provided that proper siting and disposal methods are followed.
#2: Solar energy has a low carbon footprint	Solar energy has the fifth-lowest carbon footprint out of all energy types. On a life-cycle basis, concentrating solar energy emits 38, PV roof solar energy emits 41, and PV utility solar energy emits 48 grams of CO2 equivalent per kWh of electricity produced.
#3: Solar energy protects air quality	Rather than combusting toxic materials like coal does, solar power plants harness the energy of the sun to generate electricity. PV panels and concentrating mirrors produce minimal greenhouse gasses and emit no sulfur dioxide or nitrogen oxides, thereby helping to protect air quality.
#4: Solar panels efficiently convert sunlight into electricity	Today’s PV solar cells have an average commercial energy conversion rate of 15-20%. In addition, solar energy is an efficient use of land, producing roughly 40 times more energy than one acre of corn devoted to ethanol production.
#5: Solar energy generates few waste products	Solar energy generates minimal CO2 and few other waste products upon operation, and solar panels can be recycled.
#6: Solar energy promotes energy independence and energy security	Solar energy can help us transition away from fossil fuels and towards an energy-independent future.

These Are the 4 Cons of Solar Energy

Understanding the drawbacks of solar energy is important to mitigate climate change effectively. 

4 Cons of Solar Energy	Quick Facts
#1: Solar energy is an intermittent energy source	The amount and availability of sunlight varies by location, time of day and year, and weather. The unpredictable nature of solar means we cannot rely on it fully to produce all of our energy.
#2: Solar energy has high upfront costs	The Solar Energy Industries Association estimates it costs roughly $25,000 to install an average-sized residential solar system in the US, before taking into account any tax incentives. Solar batteries can cost between $12,000 and $20,000 to install, depending on the type and size.
#3: Solar energy can be expensive to maintain	Routine solar panel maintenance can cost between $140-$180 per service, and solar panel cleaning can cost $25 per panel. Optional solar system monitoring, roof and solar panel repairs, and tree trimming can be additional hidden expenses.
#4: Solar energy has specific land requirements	Utility-scale solar farms require 5-15 flat, unobstructed acres of land close to major population centers for commercial energy generation.

How Clean, Green, Sustainable, Renewable, and Environmentally Friendly Is Solar Energy

Solar energy is one of our fastest-growing and most popular alternative energy technologies with a low carbon emissions profile. It can play an important role in the global energy transformation and help the transition away from fossil fuels.

What’s the Carbon Footprint of Solar Energy

The carbon footprint is one of the ways we measure the effects of human-induced global climate change. It primarily focuses on the greenhouse gas (GHG) emissions associated with consumption and includes other emissions such as methane (CH₄), nitrous oxide, and chlorofluorocarbons (CFCs).

“Carbon footprint: the amount of greenhouse gasses and specifically carbon dioxide emitted by something (such as a person’s activities or a product’s manufacture and transport) during a given period”

Merriam Webster

Although solar energy emits zero to no GHG emissions upon operation, there are emissions associated with other stages of its life cycle including manufacturing, transportation, installation, maintenance, decommissioning, and dismantlement of materials.

On a life-cycle basis, concentrating solar energy emits 38, PV roof solar energy emits 41, and PV utility solar energy emits 48 grams of CO₂ equivalent per kWh of electricity produced. 

Have a look at the illustration below to see the average life-cycle CO₂ equivalent emissions of different energy sources and how they compare to solar energy.

Here’s How Clean Solar Energy Is

Overall, solar energy is considered to be clean energy. 

“Clean energy: energy, as electricity or nuclear power, that does not pollute the atmosphere when used, as opposed to coal and oil”

Collins Dictionary

Solar energy produces virtually no greenhouse gasses or any other kind of environmental pollution upon its operation.

How clean is the building of solar energy	Emissions at this stage vary based on the type and size of the solar facility, with larger solar facilities requiring more materials and resulting in more emissions from construction. Essentially, the smaller the solar facility, the cleaner the building stage is considered.
How clean is the operating and maintaining of solar energy	There are very few CO2 emissions or waste products associated with operating and maintaining PV and concentrating solar energy, making this phase very clean.
How clean is the building back of solar energy	Emissions at this stage vary based on the type and size of the solar facility, with larger solar facilities requiring more effort to decommission. Essentially, the smaller the solar facility, the cleaner the building back stage is considered.

Here’s How Green Solar Energy Is

Overall, solar energy is considered to be green energy.

“Green Energy: energy that can be produced in a way that protects the natural environment, for example by using wind, water, or the sun”

Cambridge Dictionary

Solar energy has a low to zero-emissions profile and carbon footprint reductions that provide the highest environmental benefits.

How green is the building of solar energy	The building stage of solar energy has a low carbon footprint when compared to fossil fuels, and solar can have a minimal impact on the land if proper siting measures are followed.
How green is the operating and maintaining of solar energy	Solar energy emits minimal greenhouse gasses and has a minimal effect on the environment, provided that proper siting of solar facilities occurs.
How green is the building back of solar energy	Recycling end-of-life solar panels can help ensure any toxic chemicals do not leach out into the environment.

Here’s How Sustainable Solar Energy Is

Overall, solar energy is considered to be sustainable energy.

“Sustainable: The ability to be maintained at a certain rate or level | Avoidance of the depletion of natural resources in order to maintain an ecological balance”

Oxford Dictionary

Solar energy meets the needs of our current generation without compromising the ability of future generations to meet their own needs.

How sustainable is the building of solar energy	Solar panel and solar facility construction has become more sustainable in recent years with advancements in solar panel efficiency.
How sustainable is the operating and maintaining of solar energy	This stage is sustainable because we harness only a fraction of the amount of energy the sun gives off, meaning we can continue to use solar energy for many years to come.
How sustainable is the building back of solar energy	Solar panels are built to last 30 years, and they can be recycled at the end of their life cycle, which increases their sustainability.

Here’s How Renewable Solar Energy Is

Overall, solar energy is considered to be renewable energy.

“Renewable Energy: energy that is produced using the sun, wind, etc., or from crops, rather than using fuels such as oil or coal | types of energy that can be replaced naturally such as energy produced from wind or water”

Cambridge Dictionary

Solar energy is flow-limited, naturally replenishing, virtually inexhaustible, and limited in the amount of energy available in a set amount of time. 

How renewable is the building of solar energy	This initial stage of solar energy is not considered to be renewable because it involves constructing and not repurposing or re-using.
How renewable is the operating and maintaining of solar energy	This stage is renewable because we harness only a fraction of the amount of energy the sun gives off, and it naturally replenishes itself over time.
How renewable is the building back of solar energy	Solar panels are built to last 30 years, and they can be recycled and repurposed at the end of their life cycle.

Here’s How Environmentally Friendly Solar Energy Is

Overall, solar energy is considered to be environmentally friendly.

“Environmentally friendly: (of products) not harming the environment.”

Cambridge Dictionary

Solar energy does just as the word implies, it has a minimal, negative impact on the environment.

How environmentally friendly is the building of solar energy	The building of solar energy can be environmentally friendly so long as clearing the land for construction does not disturb natural habitats and degrade the land.
How environmentally friendly is the operating and maintaining of solar energy	Solar energy emits minimal greenhouse gas emissions and has a minimal effect on the environment, provided that proper siting of solar facilities occurs.
How environmentally friendly is the building back of solar energy	Solar panels themselves can be classified as hazardous waste depending on the type of metals present in the semiconductor and solder. Recycling end-of-life solar panels can help ensure any toxic chemicals do not leach out into the environment.

Final Thoughts

One of our most advanced and widespread renewable energy technologies is solar energy, the conversion of sunlight into electrical energy. Solar is generally considered safe for humans, animals, the environment, and our infrastructure, and it is an effective and efficient way of generating energy that is cleaner than traditional fossil fuels.

Solar energy is poised to see continued growth in the future as we look to reduce greenhouse gas emissions and mitigate global warming. As we look towards a future powered by renewables, solar energy is predicted to continue increasing in capacity because it benefits both our atmosphere and Earth’s biota.

Stay impactful,

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