How Solar Energy Works

The sun is one of the most powerful physical object known to man. Think about it: it's massive, over 100 times the size of the earth. It's so bright that it can blind you. It emits such intense radiation that it can burn you. Light, the fastest moving thing in the entire universe, takes minutes to travel from the sun to the earth. Pretty powerful for being a staggering 91.45 million miles away.

The sun is also the ultimate power source. It powers nearly all life on earth. The only exceptions are a handful of remote deep-sea vent and cold seep ecosystems. It is the base of the food chain, the ultimate source of the energy that all life needs to survive and to function.

So it makes a lot of sense that the sun is also a very important source of renewable energy for our homes.

There's a better way than fossil fuels

During the second half of the 20th century, it became increasingly evident that our historical reliance on fossil fuels was not sustainable.

Fossil fuels, like coal and petroleum, form only under very specific geological conditions, and the supply is finite. Burning fossil fuels generates greenhouse gases and pollutes the air. Heading into the 21st century it's become obvious that we need an alternative to fossil fuels.

And what better source of energy than the sun, that powerful star that sustains our very existence? In recent years, new developments have decreased the cost of solar energy significantly, while improving the efficiency of solar panels and solar cells.

How does solar power work?

All light, including sunlight, contains energy.

When light hits certain types of materials, that energy converts into an electrical current. The first true solar panels used large crystals of silicon. This element is an intrinsic semiconductor. Due to its atomic structure, when silicon is exposed to light, the electrons move, and an electrical current is generated. Silicon can convert a significant amount of light energy into electricity, but the cost of creating these silicon crystals can be quite prohibitive.

Newer photovoltaic materials use thin, flexible films made from less costly materials, such as copper-indium-gallium-selenide, which are combined into devices called solar cells, and arranged on solar panels.

Rooftop solar panels are best for homes in geographic areas where sunshine is reliable and tree coverage is at a minimum. The photovoltaic cells on a solar panels collect sunlight during the day, which converts into direct current. A device called an "inverter" converts this DC electricity into alternating current (AC), which is sent to an electrical panel to power your home. These solar power setups generate an excess of energy, offsetting energy use at night and during overcast weather.

How does solar energy work step-by-step?

1. Sunlight hits the solar panel
2. The photovoltaic cells within the panel turn the light energy into a direct current
3. The direct current then flows into an “inverter”, which converts the direct current into an alternating current, which can then be used
4. On a home set up, the electricity is then fed through a meter and into the home
5. The home then uses that free electricity
6. Any excess electricity not used can be fed back into the national grid to be used by others or stored for later use

How is energy produced from solar?

To understand this, we’ve got to go back to High School science classes. You may remember that light is made up of photons, which are particles of radiant energy produced by the sun. Each photon contains a different amount of energy (depending on the wavelength of the solar spectrum, but you don’t need to understand this to move on).

When light hits a solar cell, some of the photons will be absorbed, while others will be reflected. You may remember that black surfaces tend to absorb heat (which is good news for solar panels), while white surfaces reflect it. When a cell absorbs a sufficient number of photons, the electrons within the cell separate from their atoms.

The electrons then move to the front surface of the cell, which is made to be attractive to the free electrons. These electrons hold a negative charge, and so an imbalance is created between the back of the cell and the front. The space in between creates a voltage potential (like each end of a battery). When each end (in this case, surface) is connected to other sources, electricity flows.

How does solar energy work in a house?

When solar panels are placed on a home, they absorb photons from within the sunlight, and then the process explained above takes place. Once the electricity has been created, it is a “direct current,” which cannot be used in our homes. An inverter then converts this energy into an alternating current, which can flow into the home and be used for energy.

Unless a home is entirely off the grid, then excess energy will flow into the grid, where it can be used by others. The homeowner will be paid for this energy. A home will also use energy from the grid when there is not enough sunlight to create energy to power the home.

Can we run AC with solar power?

Most solar panels (on residential properties) produce an average of 250 to 400 watts per hour. Most houses need between 20-25 panels to power all their needs, including AC.

If you were thinking of running your AC exclusively off solar panels, you’ll need to consider if it’s worth it. AC systems use up to 2.5KW, so the minimum of your solar power system would need to be 3KW. That means you need around 12 panels just to run your AC, and panels aren’t cheap.

While it may make sense to run your AC when there is intense sun, the system may not be enough to keep you comfortable. Since solar systems are a big investment, you’re likely better off installing them for the whole home, or not at all.

If you’re looking for an eco-friendly way to power your AC, consider making the switch to renewable energy. Inspire provides customers access to 100% clean energy without any installation needed. Find out more about our clean energy plans here.

Can a house run on solar power alone?

Yes and no. If you have a big enough solar system, it should be able to power your entire home. However, the (big) caveat here is that it can only do so when there is a good level of sunlight. That means that you may be able to run your home from your solar panels year-round in areas like LA, but a home with solar panels in Western Washington will struggle to do so.

Which country is the largest producer of solar energy?

Currently, China produces the most amount of solar energy¹. China has over 30.1 GW of photovoltaic capacity. China’s lead used to be huge (51% more than other countries in 2021) but has decreased over time to around 27% of the entire solar market. The U.S., Japan, Vietnam, and India follow.

Who invented solar energy?

French physicist, A. E. Becquerel, was the first to discover a photovoltaic effect, way back in 1839. There’s a lot more to this story, however, which you can read more about here: Who Discovered Solar?

What are the pros and cons of solar?

Pros:

• 100% clean energy
• Renewable
• Abundant (though in some areas of the world more than others)
• Will never go away
• Cheap to maintain
• Can be installed on rooftops, rather than taking up a new footprint

Cons:

• Expensive to install
• Still can’t work at night or on overcast days
• Isn’t practical in all areas of the world

Do solar panels work at night?

Not yet. At the beginning of 2020, a group of scientists² designed a new type of solar cell that can generate power on clear nights. While it’s not a lot (about 25% of output they can get during the day), we can hope to see 24-hour solar panels within the near future.

Do solar panels work in the rain?

The rain itself does not hinder the ability of a solar panel to work, but the clouds do. Solar panels do not yet work during heavy cloud cover, which is nearly always present on rainy days.

Do solar panels work in winter?

Yes, provided there is bright sunlight. As with rain, solar panels aren’t affected by temperature, just by cloud cover, which is common in winter. It’s worth noting that solar water heaters will likely be affected by cold temperatures since they’re relying on the sun’s heat instead of the sun’s light.

Do solar panels last forever?

Unfortunately not. The useful lifespan of a solar panel is increasing all the time, but they currently last for around 20-25 years before they need replacing.

How many solar panels does it take to run a house?

The average U.S. home needs 21-34 panels to cover the entirety of their monthly utility bill³.

Are solar panels worth it?

It depends on what your goals are. If you’re looking for ways to save money on your utility bills, then installing solar panels means you won’t see the benefits of that for around 6-7 years, because the cost of the installation is so high. If you plan to sell your home in the near future, then you may be able to install them and get your money back when you sell your property.

However, for most the cost of installation and their unsuitability for so many areas of the world means that they may not be worth it, and you might be better off doing your part for the planet by switching to a renewable energy plan.

The future of solar energy

The key to improving the efficiency and cost-effectiveness of solar power lies in developing more efficient photovoltaic cells.

As solar technology develops, it could potentially become one of the world’s leading sources of electricity. A 2011 report from the International Energy Agency estimated that by 2060, solar power could potentially provide over 30% of the world's energy. This could go a long way toward reducing fossil fuel dependence and greenhouse gas emissions.

With sufficient funding for research and technological development, along with true commitment from politicians and industry leaders, the sun's energy may be one factor in getting us closer to a cleaner future.

Is solar energy right for you?

All of us here at Inspire are dedicated to decreasing the U.S’s reliance on fossil fuels and making clean energy accessible to everyone. If you want to decrease your carbon footprint, we’re here to help. Our clean energy plans can provide your home with access to 100% renewable energy at a fixed monthly price.

If you are interested in learning more about the benefits of renewable energy or how to switch to clean energy, you're in the right place. Inspire is a renewable energy company focused on lowering reliance on fossil fuels. Click the banner below to learn more.

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1. investopedia.com/articles/investing/092815/5-countries-produce-most-solar-energy.asp↩
2. sustainability-times.com/low-carbon-energy/a-solar-panel-that-works-at-night-here-it-comes/↩
3. solarreviews.com/blog/how-many-solar-panels-do-i-need-to-run-my-house↩