large solar farm in california

How Many Solar Panels Would be Needed to Power the U.S.?


Written by qualified solar engineer Aniket on August 17, 2019

About 786 million solar panels would be needed to power the U.S. on solar energy. This is derived from the fact that every year the U. S. consumes around 4000 billion kWh of electricity. This means an astounding consumption of 12,000 kWh per year per capita.

If each one of the 7.5 billion humans on the planet start consuming this amount of energy, all of the oil in the world would last only nine years. In addition to this, climate change data repeatedly points to a probable 2°C rise in average temperatures in this century, bringing catastrophes like never before. These are reasons enough to wonder how the entire U.S. can become solar powered. Let’s find out how.

The Total Installed Capacity Required

If we were to think of the solar panels needed to power the entire world, a significantly large portion of that would be needed for the U.S. alone. Currently, the existing infrastructure in the nation churns out over 4000 billion kWh every year. That means a daily average of almost 11 billion kWh.

Dividing the above number by the number of hours of energy consumption would give us hourly energy data, or simply the power consumption (kilowatt-hours ÷ hours = kilowatts). Now, unlike conventional power generation sources, solar cannot operate 24 hours a day. This is why the hourly consumption and hourly generation numbers for solar power cannot be the same.

For example, if one needs 24 kWh per day, his hourly average consumption would be 1 kW, but a 1 kW solar plant would not generate energy for 24 hours. This is due to the day-night cycles. Owing to this, the number of hours of peak sunshine at any location matters.

In our case, the full sunshine hours in the U.S. vary from 3.5 to 5.5. For our calculation, we will assume a national average or 4. This can, of course, be different based on the latitudes where the majority of the solar plants are located. Going back to our calculation, 4000 billion kWh with a 4-hour full generation every day gives us 11 billion kWh ÷ 4 hours = 275 million kilowatts, or a staggering 275 GW.

diagram to show the annual pv solar radiation in the United States(Image Source – NREL)

The current standard size of panels used in a large sized solar plant is easily over 350W. Assuming this power rating, we would need to divide 275 GW by 350W, which gives us the gigantic number of 785.7 million (785714285, to be precise) panels required. This number does look intimidating, but with a large number of solar companies in the U.S., it can be turned into reality.

Area and Costs Required

It is nearly impossible to install all these panels at a single location for more than one reason. We can, however, hope for a cumulative installed capacity crossing the required number (with plants spread throughout various states). A megawatt of solar power plant requires about 5 acres of land. 275 GW, or 275,000 MW would require 13,7500 acres.

An important point to note here is that not all the panels have to be installed on vast areas of land. Rooftop solar plants have rapidly gained traction. The number of solar panels required to power the average house, in almost all cases, would find sufficient roof space on homes in the U.S.

For many decades, high cost remained a serious obstacle in the widespread adoption of solar. In the past few years, costs of solar panels have experienced a nosedive. The installation costs don’t burn a hole in your wallet, thanks to a well-established industry with considerable competition. Focusing on large scale deployment of solar, costs can be controlled even more by purchasing panels made in the U.S.

In the end, we cannot afford to ignore the climate story. We need to make sincere efforts towards remarkably large deployment of solar power, starting today.


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