The United States and many other countries around the world are heavily investing in solar power as an energy source as part of a global effort to transition to renewable energy sources and eliminate the use of fossil fuels. To do so, there will need to be a massive expansion of solar infrastructure capable of producing massive amounts of energy. According to a recent study published by the United States Department of Energy, solar power has the potential to produce 45 percent of all electricity. This will necessitate the generation of 1,600 gigawatts of power.

Understanding how power is measured, generated, and harnessed will become increasingly important as we see a shift toward solar and other renewable energy sources. So let’s define a gigawatt, how many gigawatts of power the US currently generates, and how many it will need to generate in order to meet its future targets.

A gigawatt is a unit of electrical power measurement. A gigawatt is equal to one billion watts in this context.

You’re probably more familiar with the wattage measurement in relation to lightbulbs. If you look around your house, you’ll probably find bulbs ranging from 60 to 100 watts in your lamps and lighting fixtures. While we often think of this as the brightness of the bulb, it is actually a measurement of how much energy is required to power it.

Solar panels produce watts of electricity by absorbing sunlight via photovoltaic panels or mirrors that concentrate solar radiation. This energy is then converted into electricity, which can power anything from a lightbulb in your lamp to an entire power grid. According to the Department of Energy, it takes more than three million solar panels to generate one gigawatt of power, which can then be stored and dispensed as needed. So, what does a gigawatt of power get you? That’s a lot of light bulbs, to say the least. If you go back and look at the 100 watt bulbs you have around the house, you could power approximately 10 million of them. Switch to LED lights, which consume far less energy, and you can power over 100 million of them.

However, here’s a more practical measurement: One gigawatt of energy is enough to power approximately 750,000 homes.

Solar panels currently generate approximately 97.2 gigawatts of electricity in the United States. According to the Department of Energy, that is enough to power 18 million American homes. That is a significant increase from just a decade ago, when the country received less than one gigawatt of power from this renewable energy source, owing largely to the rapidly declining cost of solar panels and increased availability for residential buildings. Solar panels are expected to be installed in one out of every seven homes in the United States by 2030.

The average American home consumes 10,715 kilowatt-hours (kWh) per year, which equates to approximately 29 kWh per day. Because the average solar panel produces between 250 and 400 watts of power, the average home requires 20 to 25 solar panels. This varies according to geographic location, sun exposure, and the energy capacity of the panels. Regardless, solar energy contributes to lower electricity costs for the majority of people.

The United States government has set a goal of generating 45 percent of its energy through solar power by 2050 under the current administration. This will necessitate 1,600 gigawatts of power and a large number of solar panels. Many will end up on houses and property around houses, but the government will also look into opportunities to establish solar panel farms on land deemed unsuitable for other uses. To meet these targets with the current energy capacity of most panels, solar panels would need to cover up to 0.5 percent of the land surface area in the contiguous United States.

Solar power is continuing to grow, both for personal use at homes and through government expansion to help power the electrical grid in a clean and sustainable way. In order to shift to renewable energy, generating lots of solar energy will be key. That means you should expect to hear a lot more about gigawatts in the future — the more we are generating, the closer we get to the goal of a sustainable energy future.