Hybrid solar energy systems are hybrid energy systems that combine the solar energy of a photovoltaic system with another source of energy that generates energy. A common type is a hybrid photovoltaic diesel system, which combines solar photovoltaic (PV) and diesel generators, or diesel generator sets, since PV has only a marginal cost and is treated with priority in the network. Diesel generator sets are used to constantly fill the gap between the current load and the actual power generated by the photovoltaic system.
Since the solar energy fluctuates and the generation capacity of the diesel generator sets is limited to a certain range, it is often a viable option to include the storage of the battery to optimize the contribution of solar energy to the overall generation of the system hybrid.
The best business cases for the reduction of diesel with solar and wind energy can usually be found in remote locations because these sites are often not connected to the grid and the transport of diesel over long distances is expensive. Many of these applications can be found in the mining sector and on the islands
In 2015, a case study carried out in seven countries concluded that, in all cases, the generation of costs can be reduced by hybridizing mini-networks and isolated networks. However, the financing costs of diesel-powered electric networks with photovoltaic solar energy are crucial and depend to a large extent on the ownership structure of the power plant. While the cost reductions for state public services may be important, the study also identified that the short-term economic benefits are insignificant or even negative for public non-public services, such as independent energy producers, given the historical costs in the time of the study.
Other solar hybrids include solar wind systems. The combination of wind and solar energy has the advantage that the two sources complement each other because the peak operating times for each system occur at different times of the day and year. The power generation of said hybrid system is more constant and fluctuates less than each of the two component subsystems.
Solar thermal hybrid systems
Although Solar PV generates cheaper intermittent energy during the day, it needs the support of sustainable sources of power generation to provide energy throughout the day. Thermal solar plants with thermal storage are generating clean and sustainable energy to supply electricity throughout the day. They can perfectly meet the load demand and function as base load power plants when the extracted solar energy is in excess in a day. The right combination of solar thermal energy (thermal storage type) and photovoltaic solar energy can completely match the load fluctuations without the need for costly battery storage.
During the day, the additional auxiliary energy consumption of a solar thermal power plant is almost 10% of its nominal capacity for the process of extracting solar energy in the form of thermal energy. This auxiliary power requirement may be available from a cheaper photovoltaic plant by designing a hybrid solar plant with a combination of solar thermal and photovoltaic plants at one site. Also to optimize the cost of energy, generation can be from the cheapest photovoltaic solar plant (33% generation) during the day, while the rest of the time in a day is from the solar thermal storage plant (67%) of generation of the tower of solar energy and types of parabolic channels) to comply with the operation of base load 24 hours. When the solar thermal storage plant is forced to inactivate due to lack of local sunlight during cloudy days in the monsoon season, it is also possible to consume (as a battery storage system of lower capacity, lower cost and lower efficiency) the surplus / weak economic power of the photovoltaic, wind and hydroelectric power plants by heating the hot molten salt to a higher temperature to convert the stored thermal energy into electricity during the peak hours of demand when the sale price of electricity is profitable.