Various innovative solutions are necessary to make the integration of RES into the common energy system more flexible. Energy storage options are already widely used. It is possible to accumulate both electricity and heat.

Currently, the largest electricity reserves are stored directly in HPPs reservoirs, as well as in pumped hydroelectric energy storage (PHES). PHES operates in a similar way to HPPs by pumping extra water from the lower tank to the upper one. To better integrate solar and wind energy into the energy systems, pumped storage will not be appropriate. For now, electricity is stored in batteries. Although, they rapidly lose their maximum energy storage capacity and are still being improved.

In addition to batteries and energy storage in water reservoirs, other solutions for energy storage are being sought both for the short term and long term. Energy storage technologies such as compressed air storage, hydrogen production from renewable energy sources and energy storage in various household electrical appliances, including electric cars, are already being explored as potentially useful in the future. These technologies have not yet been put into practice. Energy storage opportunities are important in both commercial energy generation and energy generation for own consumption.