Solar and wind offer clean and renewable ways to produce large amounts of electricity. They have boomed over the last few years, evolving from an eco-daydream to a major market and showing unprecedented growth rates. Yet, installing solar panels and wind turbines is by no means the end of the story. The electrical grid, which connects production means to the end-users’ sockets, is not a simple electron pipe. It is the beating heart of our electricity system and ensures its stability. Solar and wind raise specific challenges for the grid, and these challenges will have to be tackled if we want to deploy larger amounts of renewable sources. The aim of this lecture is to introduce these challenges and some approaches considered to overcome them. We are convinced that everyone involved in this journey, from investors, to entrepreneur, policy makers or simple customer should be aware of these issues if we want to make sure they don’t become a bottleneck limiting further development of renewable sources.