If the world covered every suitable roof with solar panels, it could supply 2/3 of humanity’s total electricity consumption – allowing the globe to transition completely off of fossil electricity generation, according to a new study out of the University of Sussex.

The study examined satellite data to determine the total suitable roof area around the planet which could be used for rooftop solar panels. It took into account roof slope, shading from other buildings, and so on.

It found that rooftop solar could provide a total of 19,483TWh of electricity, which is about 2/3 of global electricity use (which was 29,664TWh in 2023).

This total is actually more than the amount of electricity the world currently generates from fossil fuels – that number was 17,718TWh in 2024, driven mostly by coal and methane, two highly polluting sources.

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Thus, if all of the world’s roofs were covered with solar panels, all of current fossil fuel electricity generation could be eliminated, taking a big chunk out of the unhealthy pollution created by human activities.

Certain regions are seen as more ripe for deployment of solar panels, like East Asia which has a large percentage of the world’s building stock (due to the region’s high population), and Africa where despite low housing stock, solar penetration is currently very low and solar capacity is high.

In total, the study says that this move alone could reduce global temperatures by 0.13C. While that number doesn’t seem too large, it’s a big chunk of the 1.5C warming “budget” that scientists have determined the world has to work with – and every bit of movement past that number risks additional cascading effects that will make the world less livable for humans and other species, and cause more catastrophic effects like we’re already seeing as a result of the fossil fuel industry’s operations around the globe.

The study does include a caveat that as world temperatures continue to rise, this could make certain types of solar panels less effective, leading to a drop in total generation capacity. Thus, the more we confront climate change now, the more effective this tactic will be.

However, this effect is also balanced by the potential of solar panels to be deployed more effectively by optimizing tilt angles. The study’s base case assumes flat horizontal installations – but if optimal tilt angles or solar tracking was used, the panels could be up to 39% more effective. This means if the world covered every roof with sun-tracking panels, it couldn’t just cover 2/3 of electricity production, but all of it.

It also doesn’t cover the potential of large grid-tied solar projects, just rooftops. If we used certain desert land for solar plants (which could regenerate desertified locales), that only adds to the world’s solar potential.

But we have only compared these numbers to current electricity use. The world does use energy for lots of other things – and one of the largest chunks of this is oil for transportation. As global transportation shifts rapidly to electrification, this will mean electricity use will go up significantly (though total energy use for transportation will go down – since EVs are much more efficient than gas cars).

So while rooftop solar may be enough for our current electricity needs in an ideal situation where every rooftop is covered, there will still be other sources needed to cover the rest of the shifting landscape of electricity use. Ideally, those sources will be clean – which shouldn’t be hard, given that renewables are cheaper than fossil generation.

Further, solar is less suitable in some areas than others, and for certain tasks (such as the obvious nighttime electricity use), so electricity storage (either provided by EVs, home battery systems, or grid storage) or other low-carbon generation methods like wind, hydro or nuclear still have a place, particularly in instances when they have cost advantages.

Electrek’s Take

Among some governments’ efforts to make energy more expensive and harmful to your health, it’s nice to have some good news sometimes.

This study provides that news, showing that the roofs above our heads, which currently provide no active benefit (beyond the passive benefits of heat retention, shelter from elements and so on), could be leveraged without having to build any additional structures or use any additional land, and could cover a huge portion of our current energy use.

It’s something that has been estimated by advocates many times before, but now we have a study showing just how effective rooftop solar can be.

Not to mention that it can help you save money on your energy bills, while you contribute to solving the biggest problem humanity has ever had to confront (and hey, lookie here, Electrek even has a handy affiliate link to help you find out how much money you can save… isn’t that nice!)

If you’re considering going solar, it’s always a good idea to get quotes from a few installers. To make sure you find a trusted, reliable solar installer near you that offers competitive pricing, check out EnergySage, a free service that makes it easy for you to go solar. It has hundreds of pre-vetted solar installers competing for your business, ensuring you get high-quality solutions and save 20-30% compared to going it alone. Plus, it’s free to use, and you won’t get sales calls until you select an installer and share your phone number with them. 

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