The constant increase in the popularity of renewable energy systems allows residential building users to apply solutions leading to the diversification of the energy supply. The use of RES systems in residential buildings not only contributes to a higher level of environmental care, but also significantly and measurably improves the energy efficiency of the facility. Using hybrid systems allows the supply to be reduced or eliminated from conventional energy sources. The article presents common layouts of renewable energy systems, which are successfully used in residential buildings. It also shows the impact of such systems on the amount of savings achieved in the use of energy from external or conventional sources. In residential buildings, the possibility of energy generation in the form of electricity and heat is dependent on many factors that determine the type and size of the systems used to obtain energy from renewable sources. We should assume the further and continuous development of RES, which will increase the share of electricity and heat produced in households. Technological development, decreasing prices of equipment and components used for the installation of green electricity generation systems will be a conducive factor for increasing the popularity of RES systems, not only for residential buildings but also for other types of buildings. The article also points out the economic aspect of the RES systems application. It presents the positive impact of RES installations on the environment and estimates the average time of financial reimbursement. The economic analysis concerns individual systems of renewable energy systems used in residential buildings.

It is worth mentioning that despite of the decrease of coal generation in the energy mix, the fuel remains crucial for energy sector stabilizing the energy system and securing the energy supply in Poland as well as has a positive impact on the energy security of the European Union. The development of renewable energy will be possible with conventional energy compensating the unstable operation of renewable energy sources as climate conditions in Poland do not allow for the sustainable usage of renewable energy sources and thus, their effective utilization. The modernization of 200 MW energy generating units as well as the possible construction of 2–3 similar units will enable the stabilization of the amount of electricity in the transmission grid. The modern and modernized 200 MW energy generating units are able to maintain grid operation if needed and it will be easier to phase them out gradually as prosumer energy and energy storage technologies are being developed. Due to the held and planned general and additional generation capacity auctions for years following 2020, we are assured that despite the substantial increase of distributed generation sources in Poland’s energy mix, the electricity supply to end-users will be stable and safe.