Corporate America has embraced renewable energy. The Solar Energy Industries Association says that by the end of 2018, US businesses had been responsible for the installation of more than 7 gigawatts of solar power generating capacity.

That's a mix of on-site generation (for example, solar panels on a store rooftop) and off-site generation (larger projects connected to the electrical grid).

The 7 GW total is about 0.6 percent of all US generating capacity. That may not sound like much, but remember that these companies are not primarily in the power-generation business and could have simply bought electricity from the grid. They're going to the extra trouble and expense to install their own solar power equipment for one basic reason: They think it's good business.

"While companies decide on solar for many reasons," says the 2018 Solar Means Business Report, "the number of companies committed to reducing their carbon footprint continues to increase."

The Solar Energy Industries Association, the US solar energy industry's trade association, puts out the report annually. It forecasts an even brighter future for commercial solar. "Demand will be led," the report says, "by continued corporate commitments for 100% renewable energy."

Here's the report's list of the top 10 corporate solar users:

  1. Apple, 393.2 megawatts of total solar energy generating capacity
  2. Amazon, 249.8 MW
  3. Target, 229.7 MW
  4. Walmart, 208.9 MW
  5. Switch (a data center builder), 179.0 MW
  6. Google, 142.9 MW
  7. Prologis (an industrial real estate company), 126.3 MW
  8. Kaiser Permanente (a managed health care consortium), 120.3 MW
  9. Solvay, a Belgian advanced materials and specialty chemical company), 81.4 MW
  10. Fifth Third Bank, 80.0 MW

Of the top 25 companies in terms of overall solar energy capacity, 15 rank among the Fortune 500.

The companies use rooftop solar or other on-site technology to supply energy to stores or other physical facilities that gobble power, such as server farms.

The capacity figures also include claims to the renewable energy generated by large solar panel installations located away from a company's facilities and connected to the electrical grid.

Sometimes, companies go with an off-site project because a solar installation isn't feasible at a particular store or other facility. Off-site projects also can be considerably larger than rooftop installations, providing economies of scale and making ambitious renewable-energy goals easier to reach.

"Off-site corporate procurement is growing rapidly," the report says. "The 1.6 GW of off-site systems installed since 2014 represent nearly a third of all installed commercial capacity over that time period."

Overall, the report said, "growth in corporate solar demand has been led primarily by declining prices, which have fallen by 63% over the last decade."

Solar momentum is building. "More than half of all corporate solar capacity has been installed in the last three years," the report says.

Altogether, the systems tracked in the report generate 10.7 million megawatt-hours of electricity annually, enough to power 1.4 million homes.