Sky imaging: a necessary complement to storage for efficient operation of hybrid solar-diesel off-grid power plants

[From HPAC Engineering]. In recent years, solar-diesel hybrid applications have become more and more interesting as the technology allowing for integrating photovoltaic (PV) energy into diesel power plants has improved considerably and PV investment costs have decreased.

Typical daily solar+storage power diagram (source

Technically, the main challenges have arisen from the unstable energy generation of PV power plants and the fact that traditional diesel gensets are not very flexible and can hardly deal with loads of less than 30%-40%. The whitepaper shows how accurate forecasting can help address these challenges and boost hybrid system efficiencies.


Besides storage, a second solution for dealing with intermittencies in a solar-diesel hybrid project is prediction. If sudden output changes in the solar power plant can be forecasted, then additional spinning reserve can be provided for certain time periods although not constantly.

Sky-imaging-SteadySunSolar power forecasting provides the ability to adjust the spinning reserve dynamically. In addition, knowledge about the duration of power output changes allows the optimization of the operation of the assets, both for the diesel gensets and the storage system. In the end, solar power forecasting can significantly reduce the Levelized Cost of Energy (LCOE) of solar-diesel hybrid systems.

The forecasting of the irradiation and the production of the PV plant is extremely reliable in the short-term, with sky-images cameras (like the one pictured here supplied by SteadySun) taking hemispherical photos every minute, while a forecasting algorithm provides power production forecasts for periods from 1 minute to 1 hour.

You may download the whole white-paper (10 pages) here [pdf], with contribution from The Energy.


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