Several generations of solar PV technologies have seen significant progress on many fronts in recent years.
The most established solar PV technology is wafer-based crystalline silicon (c-Si). C-Si technology entered the market more than 50 years ago and continues to account for the largest market share by far. Since then, manufacturers have reduced costs and increased efficiency significantly. The efficiency of commercially available c-Si cells is now at 21%-23% (the theoretical limit is 29%) (IRENA, 2016i).
While silicon solar PV technology has achieved maturity, several non-silicon technologies are under development and remain a long way from their technical limits. These include more advanced thin films, such as CIGS (copper indium gallium (di)selenide) and CdTe (cadmium telluride), which together represent 6.5% of the market share. In addition, several emerging and novel technologies oer the potential for even higher efficiency and lower cost.
Many technologies are experiencing major progress, passing new efficiency and other milestones on a regular basis. Cells are getting thinner, more flexible and easier to transport, with less resource-intensive and cheaper production techniques. Of the several emerging PV technologies nearing commercialisation (see Table 4.4), the most promising are perovskites and multi-junction cells.
Innovations continue in lightweight, adaptable and low-cost technologies, such as solar windows, solar roofs, spray-on solar and printed solar cells. Such developments will enable the use of PV not only on rooftops but also on building facades and windows, which will allow for large scale integration of solar into the world’s cities (IRENA, 2016i; Merck KGaA, 2016; REN21, 2016).