Until recently, investors were forced to choose among module suppliers for exposure to the solar industry. But SolarCity (SCTY.DL) has brought a new model to the market: Leases provide stable and predictable cash flows to SolarCity investors, and with solar installations growing like weeds, the company is building a great base for the future. Fool.com contributor Travis Hoium sat down to discuss why SolarCity is so hot, and talks about other solar companies to watch.