Solar PV power is a commercially available and reliable technology with a significant potential for long-term growth in nearly all world regions. This roadmap estimates that by 2050, PV will provide around 11% of global electricity production and avoid 2.3 gigatonnes (Gt) of CO2 emissions per year. Achieving this roadmap's vision will require an effective, long-term and balanced policy effort in the next decade to allow for optimal technology progress, cost reduction and ramp-up of industrial manufacturing for mass deployment. Governments will need to provide long-term targets and supporting policies to build confidence for investments in manufacturing capacity and deployment of PV systems. PV will achieve grid parity -- i.e. competitiveness with electricity grid retail prices -- by 2020 in many regions. As grid parity is achieved, the policy framework should evolve towards fostering self-sustained markets, with the progressive phase-out of economic incentives, but maintaining grid access guarantees and sustained R&D support.