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How Many Solar Panels To Power the US?

Have you ever wondered if its possible to power the US only with solar panels? Find out how many modules would be needed here.

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Carlos Huerta
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In 2020, the U.S. was responsible for generating 4,571 million metric tons (MMmt) of energy-related CO2. Around 1,448 MMmt of these emissions were caused by the U.S. electric power sector. This sector generates 54% of its energy with coal and 44% with natural gas. These greenhouse emissions are dangerous for the environment and could increase natural disasters caused by climate change.

Powering the whole U.S. with solar energy would greatly reduce energy-related CO2 emissions. To power the whole country, the US would require to install a very large solar farm with about 6 billion solar panels for a high generation capacity that could amount to a solar capacity of under 3.2 TWp. This is quite an achievement, considering that biggest solar farm in the world is the Bhadla Solar Park in India with only 2.25GW.

In this article, we will be calculating the approximate photovoltaic (PV) system that would be needed to power the whole country with solar panels. Here we will cover simple formulas to make this calculation, estimating the results by considering actual consumption and solar radiation in the country, and we even check out some projects that could be set in the future to achieve this.

What Is the Annual Power Consumption of the US?

Before diving into the formulas to calculate how many solar panels are required to power the US, we should know how much power the whole country demands. According to the U.S. Energy Information Administration (EIA), electric utilities all over the country sold around 3.66 trillion kWh in 2020 to their customers, representing 96% of the whole power consumption.  

The 100% of the energy consumed in the country would add up to 3.8 trillion kWh, but this unaccounted 4% representing 0.14 trillion kWh, is the direct use of electricity in the US. Directly used electricity is the energy produced and consumed by the same consumer, this considers both residential and commercial solar installations with solar photovoltaic (PV) systems, wind electric systems, and other renewable energy sources.

To calculate the number of solar panels required to power the US, we will only consider the energy sold by utilities. This means that we are going to calculate the system by considering a yearly demand of 3.66 trillion kWh, which is the same as 3.66 x 10^12 kWh = 3.66 x10^15 Wh = 3.66PWh(Petwatts).

How Can We Calculate the Number of Panels Needed?

With the yearly power demand of the U.S. in hand, we can size a DC system large enough to meet this demand with solar energy. To calculate the number of panels required for this PV system, we are going to use three simple formulas, which are the following:

The first formula helps us calculate the average power demand in one day. For this formula, we need to divide the yearly consumed energy by the days in a year.

The second formula we need, helps us size the DC system required to power the country. This is a very simple formula that divides the daily energy demand by the Peak Hours of Sunlight (HPS) and a derating factor. This last one is a loss factor that considers real-world operability for PV systems (taking into consideration design factors such as tilt, orientation, temperature, and shading) when compared to nominal conditions of the panels . Particularly, a value of 0.6 also assumes efficiency losses in energy storage capabilities which would be required to power the US at night.

Knowing the DC size of the PV system that will power the country, we can now calculate the number of panels. For this calculation, we will need to divide the DC power of the system by the power rating of the panels used in the installation.

With these three formulas, we can know how many panels would be required to power the US, these are the same steps you would go through to calculate how many panels you need to power your home.

Calculating Solar Panels Quantity

With the information and required formulas in hand, it is time to calculate how many solar panels would power the country. First, we will calculate the average daily consumption of the U.S. with formula (1).

Knowing the daily energy demand of the U.S., we can calculate the DC size of the PV system. To achieve optimal sun peak hours, we will consider a state with more sun peak hours per day. In this case, we will pick Texas, since this state has solar radiation of 4.5 – 6 kWh / m2/ day or 4.5 – 6 sun peak hours, but we will use 5.25 HSP, which is the medium of 4.5 – 6. With this information, our solar system will have the following size:

To power the U.S., we require a 3.18TWp PV system that allows the country to fully dive into renewable energies and leave the combustion-generated energy behind once and for all. To calculate the number of panels, we should consider high-end solar panels that deliver a high power output. In this case, we will be using 540W PV modules. With these panels, we require the following number of solar panels.

As you can see from our calculations, a PV system with a 3.18 TWp generation capacity comprised of around 5.89 billion PV modules, could be enough to power the demand of the whole country.

Are There Plans to Power the US With Solar Panels?

While there are no current projects in place to power the U.S. with solar panels, this idea has been proposed several times by a well-renowned celebrity in the engineering sector. No one other than Elon Musk has openly spoken about powering the U.S. with only solar energy, detailing specific numbers for this.

The first time Musk spoke about it, he did so at the 2017 Governors Association Meeting. Years later, he said again on his Twitter account, defending solar energy against a video of Bill Gates, in which Gates stated that the only way to power the country with clean energy, was by using nuclear power.  

The idea of Musk to power the U.S. with solar energy is in theory quite simple. He states that the country only requires a PV system installed at a location in Texas or Nevada, occupying a 100 x 100 miles area. Aside from the PV system, he proposes a battery storage system installed in a 1 x 1-mile area, allowing the country to be fully powered with solar energy 24/7.

Conclusion

An installation with 6 billion solar panels, is quite a challenge, but it is necessary to reduce the greenhouse emissions caused by the energy sector in the States. While placing the whole generation of the country in one spot is not strategically viable, this can work as a guideline to pave the road for going 100% renewable.

Instead of one giant installation, there could be sectional solar farms in each state, allowing each of them to generate their solar power locally. For states with fewer sun peak hours, the designated farm could be placed in a neighboring state with higher solar radiation.

This calculation might only be the start, but the road for solar energy is promising. Knowing that Elon Musk, one of the most revolutionary minds in the solar and energy sector is up for the idea, shows that the goal could be met in the following decades, allowing the U.S to become a country with a lower carbon footprint.

Frequently Asked Questions (FAQs)

Will Solar Energy Be the Only Renewable Source Used in the US in the Future?

Currently, the U.S. diversifies its renewable energy portfolio among many renewable sources. The country generates part of its clean energy by using Biomass, Hydropower, Geothermal, Wind, and of course, solar energy. While in the future solar energy might be the most prominent one, this does not mean that the demand of the country could be met using several renewable energy sources instead of just solar.

How Much Will Powering the US With Solar Energy Reduce Greenhouse Emissions?

As of today, the U.S. generates around 1,448 MMmt of CO2 in the electric power sector, representing around 32% of the CO2 emissions in the energy sector. If the whole country was powered with solar energy, these emissions would be practically eliminated, allowing the country to cut its CO2 emissions by 14,480 MMmt every 10 years. This is the same as not burning 1.4 billion gallons of diesel or 33.5 million barrels of oil.

Can the Whole World Be Powered Using Solar Energy?

The U.S. is currently the second country with the highest electric power demand in the whole world, with China claiming the first position in the list. Even though China represents the biggest challenge, since powering the U.S. with solar power is viable, powering the rest of the world with solar energy is also a possibility.

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Author Bio

Electrical Engineer with background in solar PV designs for residential and commercial projects as well as power systems development. Fan of renewable energy topics and projects. Technical writer for papers, articles and research in related topics to sustainability and especially solar power.

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