EGEB: Rooftop solar could match annual total US power generation

In today’s Electrek Green Energy Brief (EGEB):

• The US has enough usable rooftop space to deploy solar that would match current generation levels.
• Renewables will make up most global generation increases to 2050, but will coal still hang around?
• UnderstandSolar is a free service that links you to top-rated solar installers in your region for personalized solar estimates. Tesla now offers price matching, so it’s important to shop for the best quotes. Click here to learn more and get your quotes. — *ad.

US rooftop solar potential

The US has enough usable rooftop space to deploy enough solar power that would match its current generation levels, according to a recent study. The paper, which was published on Nature Communications, came from scientists at the University of Cork in Ireland who assessed global rooftop solar PV potential.

US rooftops could host enough capacity to produce an annual 4.2 petawatt-hours (PWh) per year, which slightly surpasses the country’s current total energy output of around 4 PWh per year. (The petawatt (PW) is equal to one quadrillion [10¹⁵] watts.)

And that’s just the start, because solar panels are currently around 15-22% efficient, and that’s continues to improve with technological innovations. Solar panel efficiency is the percentage of sunlight a single solar panel can convert into electricity.

On a global scale, the study notes:

As the fastest deployable energy generation technology with the highest year-on-year growth rate, solar PV technology is projected to supply 25–49% of the global electricity needs by 2050 while providing employment for up to 15 million people between 2018 and 2050. Out of this, [rooftop solar photovoltaics] deployment will contribute up to 40% of the total solar PV-derived electricity generation by 2050.

Read more: Here are the 3 biggest trends in rooftop solar and battery storage

Mostly renewables, but maybe still coal?

The US Energy Information Administration’s (EIA) “International Energy Outlook 2021” report makes projections based on legal and regulatory inertia – that is, the assumption that current laws and regulations stay as they are into the future.

Using that model, the EIA projects that renewables, particularly solar and wind, will be the largest contributor to global growth in electricity generation through 2050. (That’s consistent with the University of Cork study noted above.)

However, it predicts that certain regions will still mainly use coal for electricity generation. The EIA has a really interesting take on coal consumption (and I’m not panicking – yet – because I assume laws and regulations will change):

The absence of regional carbon policies or regulations along with rising natural gas prices after 2030 — particularly in Asia and in regions that rely on higher-cost liquefied natural gas (LNG) — is likely to make coal the most economical generation fuel to pair with increased intermittent generation from wind and solar. This shift reverses the trend observed over recent decades. Although the cost of mining coal will likely raise coal prices after 2030, we project that coal prices will remain low relative to natural gas prices and provide a cost-competitive option to natural gas-fired generation.

Increases in coal-fired generation in Other non-OECD Asia – which includes Indonesia, Vietnam, and Thailand, among other countries – will account for over 75% of our projected increase in global coal-fired generation from 2030 to 2050. For Other non-OECD Asia, we project that renewable energy sources will account for about 60% of the generation increase over the projection period, primarily from wind and solar. Coal-fired generation will account for nearly all of the remaining growth.

But… on September 24, the Bank of China said it would no longer provide financing for new coal mining and coal power projects outside China, and that announcement preceded the official release of the EIA’s report in October.

So China’s big decision to cancel coal financing abroad will certainly influence “Other non-OECD Asia” countries to look more toward renewables, since they previously got most of their coal financing from China. That effectively impacts 44 coal plants earmarked for Chinese state financing totaling $50 billion.

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