Fundamentally, Solarcity uses less of everything to install mass produced high efficiency modules. It's just plan math here. They use approx 1/3 less of everything, compared to a standard efficiency panels of lower panel cost. As we know, at a scale with automation advances Solarcity has put in place (Elon influence here), you can see how overall cost will go down.
Soft costs revolve around permitting and inspection times and specifically in California,(which is 50% of all installs) they enacted legislation that significantly reduces permitting time.
In addition, Solarcity will continue to buy current demand of Chinese panels and is expected to only increase its orders, so Chinese manufacturers will continue to produce at capacity. Also, Solarcity buys tarring free panels in Mexico for operations there so I expect non stop demand for Chinese panels. Bottomline, Solarcity is ordering from all its suppliers in addition to its own module manufacturing self consumption.
I know those that have invested in Chinese stocks are hurting too right now, but it's not Solarcity's fault. Makes no sense to troll it to pump your own.