The solar lease has become a huge driver of revenue from solar installers such as SolarCity (NASDAQ:SCTY.DL) and SunPower (NASDAQ:SPWR). But equity financing that takes advantage of tax credits is becoming a limiting factor to industry growth. One alternative is the solar loan, something SunPower recently unleashed in Australia. Solar analyst Travis Hoium covers why this and other financing options are so important to solar growth.