Massachusetts Institute of Technology (MIT), a Cambridge, Massachusetts-based research university, has studied the more than 99% decline in solar photovoltaic (PV) panel costs since the 1970s. According to MIT, this reduction was driven by 81 innovations in PV modules and balance-of-system (BOS) components, identified using a quantitative cost model and literature analysis. Hardware advancements such as antireflective coated glass and wire sawing, which alone cut PV system costs by $5/W, contributed the largest share of savings. BOS cost reductions were achieved mainly through process innovations, including automated permitting, streamlined installation techniques, and advanced project management tools, though their historical impact was significantly smaller than hardware’s.MIT has stated that innovations have originated from industries including semiconductors, metallurgy, electronics, petroleum, glass manufacturing, software, and utilities. The study has highlighted that timing, policy support, and cross-industry knowledge transfer were critical in accelerating adoption.