Elon Musk took a lot of heat last year when his Tesla Inc. bought solar-panel installer SolarCity for $2 billion. The synergies between his two companies didn’t seem immediately obvious, among other issues, critics said.
But now other solar installers are looking to partner with companies as they wrestle with a market that is shrinking after 16 years of rapid growth. Their longtime sales model -- knocking on doors, cold calling at home, setting up mall kiosks -- has proven to be costly. Far more effective to use the umbrella of bigger established companies to find customers, they’ve decided.