Residential solar installation costs have remained stubbornly high due primarily to non-hardware “soft” costs. We address one soft cost contributor, installation labor, by investigating the use of adhesives to attach conventional PV modules to asphalt shingled residential roofs. In addition to simplifying the installation process, (thus reducing cost) adhesive mounting eliminates roof penetrations and the associated risk of leaks. The project team has developed a non-penetrating adhesive mounting system for conventional framed c-Si modules for residential steep-slope asphalt shingled roofs. A substructure is adhered to the roof, and the PV modules are mounted to these substructures with traditional mounting clamps. The substructure transmits and distributes the module loads, including wind uplift, to the shingles. By distributing the force (and thus reducing stress) over the full area of the module, the integrity of the load-path between module and roof is maintained, ensuring that the system can meet uplift requirements. Adhesive mounting reduces residential solar LCOE by simplifying the installation process as compared with traditional mounting approaches. The labor associated with locating the rafters and flashing the penetrations is eliminated. Training and skill requirements are thus reduced, opening the PV installer labor force to a larger labor pool. Data from several studies will be presented: 1. Mechanical Load Study: Mechanical load tests (MLT) UL1703 section 21, 2. Yield Study: The impact of the reduced module-roof gap on module temperature and module performance was studied. The adhesive mounting system was compared to a reference system on a test roof-deck in Albuquerque, NM. The study determined the yield loss associated with adhesive mounting, 3. Fire testing: UL 1703 fire tests: ‘Spread of Flame’, and ‘Burning Brand’, and 4. Installation Process Assessment: A Time and Motion (TM) study was performed on an adhesively mounted system and an equivalent reference system. A professional installation crew performed both installs. The comparison indicates the labor savings associated with adhesive mounting. All current mounting approaches require roof penetration and associated flashing, which puts a time, cost and complexity floor on installation cost. In addition, rail-based mounting is heavy, has a high part-count and a complex installation process. Adhesive mounting represents a potential paradigm shift. By simplifying the installation process and removing the need for roof penetration substantial savings are possible.