Big Data technologies are often used in domains where data is generated, stored and processes with rates that cannot be efficiently processed by one computer. One of those domains is definitely the domain of energy. Here, the processes of energy generation, transmission, distribution and use have to be concurrently monitored and analyzed in order to assure system stability without brownouts or blackouts. The transmission systems (grids) that transport electric energy are in general very large and robust infrastructures that are accompanied with an abundance of monitoring equipment. Novel Internet of Things (IoT) concepts of smart and interconnected homes are also pushing both sensors and actuators into peoples homes. The power supply of any country is considered to be one the most critical systems and as such its stability is of utmost importance. To that effect, a wide variety of systems are deployed for monitoring and control. Some of these tools are presented in this Lecture with a few from the perspective of end users (Non-Intrusive Load Monitoring, Energy Conservation Measures and User Benchmarking) and a few from the perspective of the grid (production, demand and price forecasting).