Supermarket sales of solar panels and other energy-saving products are set to create 85 new jobs at the British Gas Cardiff call centre.
The utility firm has signed a five-year deal with Sainsbury's, which is promoting its own home-energy services for potential customers.
Workers at the call centre, which already employs 1,500 people, will answer calls about the products.
General manager Lynda Campbell said the jobs boost was "great news".
Sainsbury's said research showed, in the main, British consumers did not know what "microgeneration technologies" were or where they to go to buy them.
These include wind turbines, solar systems, and ground source heat pumps.