Because the system is poorly optimised for this. Imagine a system using adhesives saving $30,000. That sounds like a lot of motivation.

> For years, Fraunhofer CSE has been working with the U.S. Department of Energy, through its SunShot initiative, and other stakeholders on approaches to lowering the cost of installing solar PV, including a “Plug and Play PV” approach designed to reduce the installed cost of solar to $1.50 per kilowatt by 2020, about half of today’s average price. To meet this objective, Fraunhofer CSE and its partners have worked to develop an adhesive-based mounting system that eliminates the need for drilling holes through the roof structure and for electrical grounding, which can save installers several hours of work per site.