A 2-hour battery takes 2 hours to charge or discharge its full capacity: it can be set to charge or discharge at a slower rate, for example for 4 hours, but at only half power. Let's cut to the chase: energy storage isn't just about storing electrons anymore – it's about storing opportunities. With the global energy storage market hitting $33 billion and generating nearly 100 gigawatt-hours annually, the real question isn't whether to adopt storage solutions, but. Energy storage with more than four hours of duration could assume a key role in integrating renewable energy into the US power grid on the back of a potential shift to net winter demand peaks, says the US National Renewable Energy Laboratory (NREL). Four-plus-hour energy storage accounts for less. The energy market is observing a progression toward longer-duration battery storage, specifically 4-hour systems. The Role of the Power Conversion System (PCS) The power conversion system (PCS) is the “brain” of a battery. Different energy storage technologies offer different discharge duration ranges – a measurement indicating how many hours of energy can be delivered in one discharge cycle.