The Solar Power Potential Of Rooftops In The U.S.

A new report indicates that the equivalent of 75% of U.S. residential electricity demands could be met by rooftop solar photovoltaics on residential buildings.

If you have ever wondered how much of the electricity demand in the U.S. could be supplied by rooftop solar, a new study has the answer.

Last month the National Renewable Energy Laboratory (NREL) released the report Rooftop Solar Technical Potential for Low-to-Moderate Income Households in the United States.

As the name indicates, the study was primarily aimed at the solar photovoltaic (PV) potential on households with low-to-moderate income (LMI) levels (defined as those earning 80% or less of the area median income). Rooftop solar PV to date has been adopted primarily among higher-income households, but declining costs of solar PV are expanding the potential for solar outside of this demographic.

The study utilized light detection and ranging (LiDAR)–based scans of buildings as well as statistical techniques to estimate rooftop solar PV potential. The study found that of the 116.9 million residential buildings in the U.S., there are 67.2 million buildings (57% of the total) suitable for solar PV. Total generation potential was nearly 1,000 terawatt-hour (TWh), which is about 75% of residential consumption (although not necessarily without economical power storage options).

The potential for rooftop solar PV is primarily a function of the orientation of the building/roof. In cold climates, buildings are often orientated to maximize incoming solar radiation. In hotter climates, buildings and associated landscaping are frequently situated to avoid incoming solar radiation. This explains why some counties of Alaska and Montana have a higher percentage of potential LMI rooftops than counties in Arizona:

Rooftop solar PV potential of LMI households by county.

However, the southwest has much higher incoming solar radiation than Alaska, which means that despite the lower percentage of applicable LMI buildings, more than 100% of LMI electrical consumption could be offset by LMI buildings (which include schools and places of worship):

Percent of LMI electrical consumption that can be offset by rooftop solar generation

The NREL study had been inspired by a U.S. Department of Energy (DOE) Solar Energy Technology Office announcement that the falling cost of solar energy could result in 971 GW of solar capacity nationwide, providing 33% of electrical generation by 2050. (For reference, current U.S. installed solar PV capacity is 50 GW).

The NREL study determined that the 33% target is easily technically viable among current LMI households. However, it is important to note that the study did not estimate economic viability.

In order to achieve economic viability, the report suggests the deployment of models other than those commonly found today. The report concluded that coordination issues inherent to rental-occupied and multi-family buildings must be addressed, and models must ensure that rental-property owners are incentivized to install solar on their buildings.

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3 thoughts on “The Solar Power Potential Of Rooftops In The U.S.”

  1. I’m not convinced. First you would need large amount of storage; sun shines about half the time, and not much early and late. You still need to spend money for transmission and peak generation, or storage (which is coming down in price, but has long way to go).

    Many regions of the US not good for solar, think of Ohio or upstate NY. Not much sun in the winter, and you can’t store 6 months. Also a large amount of cloud cover. ‘

    Cheap storage technology – or lack thereof – is key. Look at Germany, they have sky high residential rates and huge solar subsidies, but will miss carbon targets. Sure they can meet most of there electricity needs for a few hours on sunny days, but that does not mean much.

    1. Note that it’s a different thing to say that we could technically produce the equivalent of 75% of our electricity consumption, and that we could do it economically around the clock. I think the math is perfectly viable, but the economics and storage would be a barrier still.

  2. Impressive info on solar power potential. Wonder if anyone has crunched the cost to covert grid? My guess, solar will not replace much conventional power production until the grid is converted to adapt the power source. The grid has mostly been a one way street from power producer to consumer. Interesting challenge to balance the to and fro of the mix. How costly to connect the grid in a way to maximise wind and solar contribution? Given the U.S. time zones, cloud cover, and seasonal variance this we be a monumental task?

    My thinking is the power generation and contribution to the grid will be marginal. That the undispatchible and variable power value is quite low. Better to utilize wind and solar to generate carbon free fuels and gas. To generate remote hydrogen and ethanol for example. Or to utilize the energy to charge (or not) batteries on open schedule.

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