According to a new report from Rocky Mountain Institute, corporations have signed contracts for 2.8 GW of solar in the United States this year, a gigawatt more than the deals signed in all previous years combined.

It’s been a banner year for corporate renewable energy. According to the latest numbers from the Business Renewables Center at Rocky Mountain Institute (RMI), corporations have signed deals to procure 2.8 GW of solar, as part of 6.4 GW of off-site renewable energy contracts in the United States penned this year.

This is not only far more than any other year, but according to RMI the 2018 deal volume for solar is 1 GW more than all other years combined. This is part of a boom in renewable energy procurement overall, with the 2018 capacity double that of the next-biggest year, 2015.

Tech leads the pack

The 22 renewable energy deals signed by Facebook, including deals for around 1 GW of large solar plants to serve data centers in Alabama, Georgia, New Mexico, Oregon and Utah make it the top company for renewable energy procurement this year. This is explosive growth from last year when Facebook only signed two such contracts, and comes as the social media giant has come under increasing scrutiny for its alleged role in the spread of false and misleading news stories in the lead-up to the 2015 election.

But while Facebook’s 1.85 GW of deals puts it well above any competition, AT&T’s 820 MW of renewable energy procurement is also a massive volume, and is particularly remarkable as this is the company’s first year of market participation. The telecom company is followed by Walmart, which has been one of the largest adopters of on-site solar, and earlier this year signed a deal to install 23 MW of solar at 21 of its facilities in Illinois.

Microsoft and Apple came in #4 and #5, which should not be surprising given that technology companies have been the leading adopters of renewable energy. However, perennial leader Google is much lower on the list this year, likely because it has already offset all of its electricity usage with renewable energy purchases.

Exxon?

The company with the third-largest corporate renewable energy purchase this year may be a bit of a surprise: ExxonMobil.

ExxonMobil is certainly feeling the heat under allegations that it deceived the public and helped to obscure the science around climate change for decades, but the reason for its adoption of renewable energy may be simpler: economics. The company has signed 12-year contracts to buy power from wind and solar projects developed by Denmark’s Ørsted to power its oil extraction in the Permian Basin, and in an email to Bloomberg, ExxonMobil cited diversification and “competitive costs”.

Four-fold increase by 2025

RMI’s Business Renewables Center tracks corporate renewable energy purchases, but was not able to provide information about when these projects will go online. It is likely that many of these projects will start by the end of 2019 to take advantage of the full 30% Investment Tax Credit (ITC). However, they could take several years to complete as under current IRS guidance developers can push out the completion of solar projects through the end of 2023 and still claim the 30% credit as long as there is continuous construction work.

RMI and others are anticipating further growth. Miranda Ballentine, CEO of the Renewable Energy Buyers Alliance (REBA) says that she expects a four-fold increase in corporate renewable energy procurement by 2025.