Large scale deployment of solar and wind changed the paradigm of the power system and electricity markets, where prices were traditionally based on marginal generation cost and closely related fuel prices. Most of the generation capacity was considered as dispatchable and available throughout most of the year. Solar and wind do not require fuel and have practically zero marginal generation cost, while being available only when the sun shines or the wind blows. This had a significant impact on the operation of the power system as well as the electricity market. IRENA is at the forefront of the discussion on how to best plan and operate a power system with large shares of solar and wind, as well as contributing to the global debate on electricity market design for renewables. Specific issues raised by Member countries have been timely addressed through the production of specific guiding documents, such as the one on grid codes for variable renewables, or by providing specific advice to Members on those issues.