Hybrid power plants (wind- or solar-diesel)

PV-diesel-hybrid-power plants without storage have rather low capital requirements. In the picture there is an option to connect the plant to the grid, which is applied in regions with an unstable grid. In the typical off-grid solution, the electricity from the solar power plant is used with priority, the diesel gensets generate the missing gap between the solar output and the load from the island off-takers.. 

The hybrid off-grid power plant without storage requires rather low investment costs. As neither solar nor wind energy are a stable source of energy and diesel gensets need a certain time for start-up, this solution normally requires the gensets to run constantly at least at a minimum load.

Hybrid power plants with storage contain an additional component in comparison to the plant-type described above. A battery storage is dimensioned in such a way that it can store energy until the diesel gensets start-up, if for example a cloud deteriorates the solar output. The costs of the additional battery components are quite substantial. So obviously, this plant type is associated with higher investment costs.

The advantages of adding a battery storage cannot be neglected either. It allows on the one hand side for turning-off the generators during daytime and on the other hand side it can increase the renewable energy penetration considerably. The penetration rate indicates the percentage of renewable energy in the total power system.