U.S. Solar Giant Sunrun Is About to Become a Rooftop Juggernaut

Sunrun Inc., America’s biggest rooftop-solar company, is set to become a behemoth through its $1.46 billion takeover of a major rival, Vivint Solar Inc.

The agreement, announced late Monday and subject to approvals, is one of the industry’s biggest, following Tesla Inc.’s 2016 purchase of debt-plagued SolarCity Corp., as well as the failed 2015 acquisition of Vivint by SunEdison Inc., the clean-energy giant that went bankrupt soon after.

The second major U.S. energy deal in as many days -- following Berkshire Hathaway Inc.’s $4 billion purchase of Dominion Energy Inc. assets -- also threatens to further weaken ...