Solar energy definitions: What is solar power?

Before we proceed further, let’s step back and take a look at what the key solar terms actually mean.

Solar means anything related to the sun. The sun is the star of our solar system, and the original source of all warmth and light on planet Earth.  

Solar energy is any form of energy that is harnessed directly from the sun’s rays. In more technical terms, it refers to the capture of electromagnetic radiation from the sun and its conversion into usable energy, in the form of heat or electricity.

Solar thermal energy is heat energy from the sun that is used to keep us warm, grow crops, and more recently, to heat water for our homes.

Solar power or solar electricity is electricity generated from solar energy. Solar panels we use on our homes do this through the photovoltaic effect, where radiation in sunlight is converted to electricity in a solar cell. This is the way residential solar panels work. 

Solar power can also be created by concentrating the energy of the sun to heat substances that can generate steam. This steam can then drive a conventional turbine to create power. However, there are only a few of these concentrated solar thermal plants in 2020, as conventional solar panels that use photovoltaic solar cells have become much cheaper and are the dominant way to create solar power.

Solar panels are a collection of solar cells that are wired together to increase power production. There are usually 60 or 72 individual solar cells in each solar panel used on a home

See how much solar panels would cost for your home

Amazing solar facts

  • In just two hours, more energy from the sun falls on the earth than the entire human population consumes in a year.
  • We could meet all of the power needs of the United States by placing solar panels on just 11.2 million acres of land. To put that into perspective, that’s just half a percent of the total US landmass.

The image below shows the total space required, divided over three locations.

Twelve million acres is all the land you need to power all of America with solar panels. Image source: Good Inc

These facts make one thing clear: mind-boggling amounts of energy can be produced from solar. Now let’s take a deeper dive and learn more about solar power, how it works, and what it’s good for.

Is solar energy considered renewable?

Solar energy is considered renewable because it does not deplete the finite resources of the earth. While the sun technically is a limited power source, NASA estimates it will continue to produce solar energy at its current rate for another 5 billion years.

Climate change and the importance of solar energy 

Humankind is facing a crisis of its own making. 

Our lifestyles are dependent on access to energy, for heating, for cooling, for lighting, for transport, and for many other things we consider essential. But the way we have traditionally made our energy is destroying our planet and putting the future of humanity at risk.

Traditional methods of energy generation, such as burning coal and gas to generate electricity emit greenhouse gases. These carbon greenhouse gases are warming our planet and changing our climate in ways that if not corrected will leave large parts of our planet uninhabitable in an alarmingly short timeframe. This is very scary and we need to change the way we do energy, fast. 

Another crucial shortcoming of fossil fuels is that they are non-renewable; if we keep using them the way we do now, they will eventually run out. 

The search for the best source of renewable energy

To reduce greenhouse gas emissions we must reduce the use of fossil fuels for electricity generation and for transport. Together these uses have caused the majority of greenhouse gas emissions.

Electric cars are emerging as the winner in the race to be the best technology for emissions-free transport.

This is making emissions-free electricity generation extremely important as it can replace traditional transport emissions as well as traditional emissions from electricity generation.

This will require a global movement to transform our energy systems away from fossil fuels, and replacing them with sources that are clean (emissions-free) and renewable (replenishes naturally).

This is where solar and other renewable energy sources come in. 

Learn more: Why solar energy is vital to the future of the planet 

Foreground: ground mounted solar panels; background: the sun rises behind a city skyline.


Solar power is the leading form of clean and renewable energy

As a result, there has been unprecedented investment in clean energy sources. Wind power, hydropower, and energy from biomass have all attracted attention. But the energy source leading the global energy transformation is solar power.

Over the last decade (2010-2020), solar energy emerged as the single-biggest new source of power generation, beating out every other fossil-fuel-based and clean energy source. And solar will remain the dominant source of new clean energy for the foreseeable future.

According to the International Energy Agency, solar power alone will account for 60% of all growth in renewable energy worldwide through 2024.  

Bar chart shows solar PV capacity growth far outpacing that from wind, hydro, bioenergy and other energy sources

What are the benefits of solar energy?

Solar power technology is used practically throughout the world for both grid-connected and off-grid applications. Solar power systems have many advantages over other non-renewable energy technologies and also other sources of renewable energy such as wind energy.

Solar is the best way to generate power at home 

Energy is an essential part of our lives, and demand for it is constantly growing. Right now, most power is generated in large power plants using fossil fuels such as natural gas.

Renewable energy sources like solar are a growing, but still small, source of power at the utility level. 

It’s a different story for power being produced on a smaller scale. When it comes to on-site generation at homes and businesses, solar is almost always the best choice. That’s because solar power is affordable and easy to install. 

For most homeowners, the power they can generate with solar panels works out to be much cheaper than the power they buy from their utility company.  

Other energy sources may make sense on a utility or even commercial scale, but are just too costly or impractical to be installed at home. 

Without going into too much detail, here are the shortcomings of the other energy sources on a residential scale: 

  • Electrical generators are easy to buy and install but very expensive to run due to high fuel costs 
  • Hydropower requires water running through your property – and upfront costs are very high
  • Wind requires high speed winds where you live – and turbines are expensive

The fuel for solar energy is free

You don’t have to pay to use sunlight. All you need is a rooftop or open space that’s exposed to sun and you’ll have access to a free source of daily fuel for your solar power system. 

This is a big advantage over generators and other fossil-fuel powered sources of electricity, where fuel is an ongoing and ever-changing cost. 

Solar energy is available everywhere 

The sun shines all over the world. Although some locations receive more sun than others, solar panel systems can generate plentiful power almost everywhere. 

Get this: states with relatively cold, dark winters, such as New Jersey, Massachusetts and New York are all among the top 10 states for solar. This is due to excellent pro-solar policies and the fact that they can produce and sell lots of power in the summer.

Rows of ground-mounted solar panels on a snow-covered field, with mountains in the background

Solar energy can be generated anywhere – even in mountainous and snowy places.

Solar panels last a long time

Solar panels are very durable. It’s pretty rare for one to stop working; they have a failure rate of just 0.05% per year. And they’re built to withstand extreme weather conditions such as hail and high-speed winds.

Most manufacturers offer a 25-year warranty on solar panel output. However, experts believe that most solar panels will produce power for 30-40 years.

Learn more: How long do solar panels last?

It’s easy to expand a solar power system

Solar panel systems are modular, meaning it’s possible to add, subtract, or change the system even after it’s been installed. Systems can start small and grow as your energy needs increase or your budget allows.

Solar panels are quiet

Solar energy systems have no moving parts, so they don’t make any noise when they produce power other than a soft electric ‘hum.’ And they are completely silent at night, as no power is generated then.

No moving parts meaning no maintenance

There are no moving parts on a solar power system meaning there is no regular maintenance required. This is a big advantage that solar energy has over wind energy. Wind turbines need constant maintenance.

Learn more: All the pros and cons of solar energy in 2020

From sunlight to solar power: How does solar energy work?

It almost seems like magic – utilizing power from the sunlight that’s all around us and turning it into an energy source that can run appliances, HVACs and even electric cars. So how does it work?

Let’s take a look at how sunlight gets transformed into electricity that is usable for homes, businesses, and the electric grid.

The equipment required to generate solar power

Let’s look at all the components that go into a solar panel system.

A solar cell is an electrical device that contains a semiconductor material – generally silicon – that produces electricity when sunlight hits it. The energy produced by solar cells is direct current (DC) electricity.

A solar panel is a collection of solar cells that are attached together in a frame and covered in glass. There are usually 60-72 solar cells in each individual solar panel. Solar panels are also called photovoltaic (PV) panels or solar modules.

A solar array is multiple solar panels wired together.Solar cells form a solar panel, solar panels form a solar array, and a solar array with allied equipment makes a solar panel system

The components of a solar panel system.

A solar panel system is the complete setup that provides usable solar electricity. It generates and transmits power in a form that is ready for usage, storage, or to export to the grid. It may be comprised of a single or multiple arrays and is combined with accompanying equipment such as mounting and racking, wiring, etc. 

The solar inverter is the most important part of a solar system after the solar panels. The inverter’s job is to receive the DC power generated by the solar array and turn it into AC electricity that can either be used on-site or sent to the grid. 

Learn more: 

What are solar panels? A beginner’s guide

How does solar energy work and how do we use it in our homes? 

What equipment do you need for a solar power system?

Wiring solar panels: Do you wire solar panels in series or parallel?

How does solar energy work with the grid?

Solar power systems interact with the electricity grid differently depending on the scale of the project. 

Utility-scale solar power and the grid 

Solar power plants (also known as solar farms) are usually owned by the utility, or are built for the purpose of selling their output to the utility. That means the power only ever flows in one direction, i.e. from the solar power plant to the grid. 

Home solar power and the grid

Home solar power systems have a more complicated – but also more advantageous – relationship with the grid. Here, the flow of power can work both ways; the home can sell power to the grid, but also buy power from it when needed. 

This two-way, buy-sell relationship means that a home with solar doesn’t need a backup generation source. When the sun isn’t shining, they can simply import power from the grid. It also means that expensive batteries aren’t required – when the panels produce too much power, it can simply be sold to the grid. 

This video explains how a grid-connected solar system works to power a home: 

Beyond solar panels: Other uses for solar energy

Up until this point in the blog, we’ve focused almost exclusively on solar power that’s produced from photovoltaic solar panels. However, it’s important to know that there are many other ways solar energy can be put to use. 

Here’s a quick look at other important solar energy technologies. 

Passive solar design (aka solar heating and cooling)

Passive solar design uses the structural elements of a building in order to heat and cool it, in an effort to reduce the use of high-consumption equipment like HVACs. 

With passive solar design, you’ll need to take into account the following factors in order to have a successful project:

  • Careful consideration of the local climate;
  • The solar energy resource; and
  • Building orientation and landscape features. 

Learn more: Passive solar heating explained

Solar hot water (aka solar thermal)

Adding a solar hot water, or solar thermal system to a home can be relatively easy and of the most cost-effective ways to incorporate renewable energy into your life. 

A properly designed system operates efficiently regardless of outside temperature, and when used together with a backup gas or electric heater, provides ample hot water while cutting down fossil fuel use by up to 80%.

Learn more: The best solar water heaters for your home

Solar cooking 

Solar cooking is a viable renewable alternative and is one of the simplest examples of solar technology. Solar ovens can be built from a wide range of materials and are capable of reaching temperatures of 400 degrees fahrenheit or more. 

How much money can solar panels save you annually?

Concentrating Photovoltaics (CPV) and Concentrating Solar Power (CSP)

Both these technologies are similar, as they use mirrors or special lenses to magnify/concentrate direct sunlight. However, there are some crucial differences between them.

Concentrating Photovoltaics (CPV) is a solar electric technology. A CPV converts magnified light into electricity through the use of solar cells. 

Concentrating Solar Power (CSP) is a solar thermal technology (also known as heat-based, or solar thermoelectricity) that uses magnified light to create heat. It runs a steam turbine which powers a generator, producing electricity.

Both technologies are only feasible at the utility scale.

Bill Gates’ solar success: Heliogen Concentrating Solar Power

In November 2019, a secretive company named Heliogen made a big announcement. The company – which is backed by billionaire Microsoft founder Bill Gates — had used Concentrating Solar Power to achieve record-high temperatures of over 1,800 degrees fahrenheit.

The breakthrough was achieved by using Artificial Intelligence (AI) to optimize the movements of the solar mirrors, which in turn provided increased amounts of heat-generating magnified (aka concentrated) sunlight.  

This technology could play a role in the fight against climate change. The extreme heat it generates is ideal for industries that rely on such heat — like cement manufacturing — that are responsible for a high share of global carbon emissions. 

How can you use solar energy in your life?

From reading this blog you will have learned that solar power is a versatile technology with many applications. This now brings us to the next question: 

How can you apply the benefits of solar energy to your own life? 

There are many answers to that question. Gone are the days when the only solar-powered devices on the market were handheld calculators and wrist watches! Improvements in solar panel technology mean that solar equipment can be made lighter, cheaper, and more powerful than ever before.

Here are some of the most convenient and cost-effective applications of solar power available today.

Solar-powered kits and generators

If you’re an avid camper, hiker, or outdoor enthusiast, you now have a huge variety of solar options. 100-watt solar panel kits are portable, easy to use and are a great source of power for RVs or those who enjoy camping outdoors. 

If you also want backup power, then consider solar-powered generators.

Solar-powered phone chargers

For those who just want to keep their phone alive when they’re on the go, check out our list of the six best solar phone chargers currently available.  

Solar-powered gifts

And if you’re looking for fun devices for a friend or a loved one, check out our blog on great solar-powered gifts.  

Solar power system for your home = highest savings 

If you are a homeowner who wants to save money – and reduce your carbon footprint in the process – you should seriously consider getting rooftop solar panels. 

Right now is a great time to go solar. Thanks to big price drops, solar panels are now cheaper than ever. And there are generous government incentives, such as the 26% federal tax credit, that are currently available (but scheduled to end soon).

In many states, you can now see savings of up to $70,000-$100,000 over the lifetime of your solar panel system.

The calculator below will show you total costs, savings, and even the total reduction in C02 emissions you can achieve. I encourage you to try it out to see if solar power is right for you. 

Find out how much you can save by going solar. See local rebates and incentives!

Importance of the solar energy industry in 2020

More than 2 million homes had solar panels installed on them by the end of 2019.

While the COVID-19 crisis has slowed solar installations, Q1 2020 hit a Q1 installation record (Q1 is traditionally a slow quarter) and tied with Q4 2019 as the largest ever quarter for residential solar. This report gives a good update on the solar industry in Q2 2020 in the wake of the pandemic.

The majority of solar power production is for utility-scale solar projects that have many megawatts (a megawatt is 1,000 kW) of solar panels each.

There are more than 81.4 gigawatts (GW) of solar installed in the U.S., enough to power more than 15.7 million homes.

The solar industry employs more than 250,000 people in all 50 states making it one of the nation’s most significant sources of employment.

Image source: The Solar Foundation

Overcoming the disadvantages of solar energy

The disadvantages of solar energy are mainly the cost to establish it and the fact that it is an intermittent energy source. Those in the coal and oil industries who oppose solar use these things as a way to attack it.

However, the cost of solar at the utility scale has fallen so much that it is now actually cheaper to add new solar electricity capacity than it is to add new coal and gas-fired power plants. Given this is now the case opponents of solar can now only attack it on the basis that it is intermittent (i.e. it does not work at night and so on its own, it can’t be relied upon as baseload power).

This is where energy storage solutions come in. Utility-scale solar farms with energy storage can guarantee 24×7 power availability just like gas or coal-fired power stations. The only catch is that at this point the cost of the energy storage would make this more expensive as a baseload power option as compared to coal or gas.

However, our planet cannot survive with coal and gas electricity generation so investments in reducing the cost of energy storage solutions are crucial. It is important that governments globally support energy storage for renewable generation.

Currently, solar energy storage costs around $0.19 per kWh, which is based on a Tesla Powerwall costing $10,000 with the capacity to store 14kWh of electricity and releasing it at a peak rate of 5kW per hour. So energy storage that guaranteed 1 megawatt of baseload power would cost $2 million, or 200 Tesla Powerwalls.

Add another $1.5 million for the PV generation and you arrive at $3.5 million per mW of reliable baseload power using solar and battery storage with a 3-hour capacity at night.

This is more expensive than the cost to build a combined cycle gas or coal-fired power station (although some reports claim coal does cost $3.5 million per mW). However, when the cost of the coal and gas needed over time is considered, the two are economically very similar in terms of levelized cost per kW of the baseload electricity delivered.

The cost of battery storage only has to fall another 50% for solar and battery storage to be a clear winner over coal or gas. In fact, an NREL battery energy storage cost projection study released in 2019 suggests that this will be the case before 2030.

Ideas for solar energy essays

Much of the information on this page can help you write essays about solar energy and answer many of the questions you may be asked.

Here are some other great ideas for solar essays and educational projects:

  • Using a solar estimator like this one to place solar panels on the roof of your home. You can take a screenshot of the results and add it to your project. Just use the name “Test-Student” when going through the estimator.
  • Researching what batteries and energy storage technologies are emerging that may help to make solar and energy storage cheaper and better. While lithium-ion batteries are currently popular, there are many companies working to improve other types of batteries.
  • Looking into what new types of solar cells may emerge that could make solar a quantum-leap better. Current solar cells are around 20% efficient but NREL researchers in Colorado recently invented a solar cell that was 39% efficient in natural sunlight. It is amazing what may be possible.

If you are looking for a cool, big-picture college assignment idea then consider the effect of zero marginal cost energy on the future economy. Learn more by watching this Ted Talk.

Solar training and how to get into the solar industry

The solar industry is one of the fastest-growing industries in our country and it presents many career opportunities for journeymen to finance executives.

There are great solar industry training resources available both online and often at your local community college.

Standards for solar training are set by a body called NABCEP, the North American Board of Certified Energy Practitioners.

Individual training providers then deliver courses that are designed to cover the required syllabus for solar salespeople and solar installers.

The largest and best-known training provider is the non-profit Solar Energy International. They offer both free and paid courses online and at their training center in Paonia, Colorado. SolarReviews sent our content team to Paonia in 2019 to complete their intermediate solar training course and they loved it.

The great thing is that you can do their free course online first.

The future of solar

Over the past decade, solar energy has exploded in the US, thanks to falling prices and evolving technology. Solar panels are now more efficient than ever, while selling for the cheapest prices. And the prices are predicted to get even lower in the future. 

The record-low prices of solar, combined with the 26% federal tax credit make 2020 the cheapest year to go solar yet. And although the federal tax credit is set to expire at the end of 2021, Solar Energy Industries International (SEIA) still believes that over 5,000 megawatts of solar will be installed in 2023. 

Plus, as the cost of solar continues to decline, the levelized cost of energy will drop as well. In fact, the cost of solar energy is predicted to fall so low that fossil fuels won’t be able to compete. As we continue to focus on building clean energy infrastructure, we will see a greener, cleaner, and cheaper future! 

This guide to solar energy and solar power draws on training materials from Solar Energy International, the leading solar job training organization in the United States.

Find out if solar is worth it for your home