Solar hybrid power systems

Solar hybrid power systems are hybrid power systems that combine solar power from a photovoltaic system with another power generating energy source.[1][2] A common type is a photovoltaic diesel hybrid system,[3][4] combining photovoltaics (PV) and diesel generators, or diesel gensets, as PV has hardly any marginal cost and is treated with priority on the grid. The diesel gensets are used to constantly fill in the gap between the present load and the actual generated power by the PV system.[2]

Hybrid solar and wind system

As solar energy is fluctuating, and the generation capacity of the diesel genesets is limited to a certain range, it is often a viable option to include battery storage in order to optimize solar's contribution to the overall generation of the hybrid system.[2][5]

The best business cases for diesel reduction with solar and wind energy can normally be found in remote locations because these sites are often not connected to the grid and transport of diesel over long distances is expensive.[1] Many of these applications can be found in the mining sector [6] and on islands [2][7][8]

In 2015, a case-study conducted in seven countries concluded that in all cases generating costs can be reduced by hybridising mini-grids and isolated grids. However, financing costs for diesel-powered electricity grids with solar photovoltaics are crucial and largely depend on the ownership structure of the power plant. While cost reductions for state-owned utilities can be significant, the study also identified short-term economic benefits to be insignificant or even negative for non-public utilities, such as independent power producers, given historical costs at the time of the study.[9][10]

Other solar hybrids include solar-wind systems. The combination of wind and solar 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 such a hybrid system is more constant and fluctuates less than each of the two component subsystems.[11]

The intermittent / non-dispatchable solar PV at the prevailing low tariffs clubbed with pumped-heat electricity storage can offer cheapest dispatchable power round the clock on demand.

Solar thermal hybrid systems

Though Solar PV generates cheaper intermittent power during the day light time, it needs the support of sustainable power generation sources to provide round the clock power. Solar thermal plants with thermal storage are clean sustainable power generation to supply electricity round the clock.[12][13] They can cater the load demand perfectly and work as base load power plants when the extracted solar energy is found excess in a day.[14] Proper mix of solar thermal (thermal storage type) and solar PV can fully match the load fluctuations without the need of costly battery storage.[15][16]

During the day time, the additional auxiliary power consumption of a solar thermal storage power plant is nearly 10% of its rated capacity for the process of extracting solar energy in the form of thermal energy.[14] This auxiliary power requirement can be made available from cheaper solar PV plant by envisaging hybrid solar plant with a mix of solar thermal and solar PV plants at a site. Also to optimise the cost of power, generation can be from the cheaper solar PV plant (33% generation) during the day light whereas the rest of the time in a day is from the solar thermal storage plant (67% generation from Solar power tower and parabolic trough types) for meeting 24 hours base load operation.[17] When solar thermal storage plant is forced to idle due to lack of sunlight locally during cloudy days in monsoon season, it is also possible to consume (similar to a lesser efficient, huge capacity and low cost battery storage system) the cheap surplus / infirm power from solar PV, wind and hydro power plants by heating the hot molten salt to higher temperature for converting stored thermal energy in to electricity during the peak demand hours when the electricity sale price is profitable.[18][19]

  • Typical wind and solar hybrid system
  • Hybrid on Žirje, Croatia
  • Small wind and solar hybrid system

See also

References
  1. Thomas Hillig (22 January 2015). "Renewables for the Mining Sector". decentralized-energy.com.
  2. "Hybrid power plants (wind- or solar-diesel)". TH-Energy.net – A platform for renewables & mining. Retrieved 12 May 2015.
  3. Thomas Hillig (24 February 2016). "Hybrid Power Plants". th-energy.net.
  4. Amanda Cain (22 January 2014). "What Is a Photovoltaic Diesel Hybrid System?". RenewableEnergyWorld.com.
  5. Kunal K. Shah, Aishwarya S. Mundada, Joshua M. Pearce. Performance of U.S. hybrid distributed energy systems: Solar photovoltaic, battery and combined heat and power. Energy Conversion and Management 105, pp. 71–80 (2015). DOI: 10.1016/j.enconman.2015.07.048
  6. http://www.th-energy.net/english/platform-renewable-energy-and-mining/database-solar-wind-power-plants/
  7. Thomas Hillig (January 2016). "Sun For More Than Fun". solarindustrymag.com.
  8. http://www.th-energy.net/english/platform-renewable-energy-on-islands/database-solar-wind-power-plants/
  9. "New study: Hybridising electricity grids with solar PV saves costs, especially benefits state-owned utilities". SolarServer.com. 31 May 2015. Archived from the original on 26 July 2015.
  10. "Renewable Energy in Hybrid Mini-Grids and Isolated Grids: Economic Benefits and Business Cases". Frankfurt School – UNEP Collaborating Centre for Climate & Sustainable Energy Finance. May 2015.
  11. "Hybrid Wind and Solar Electric Systems". energy.gov. DOE. 2 July 2012.
  12. "Solar Reserve awarded AU$78/MWh Concentrated Solar Power contract". Retrieved 23 August 2017.
  13. "LuNeng 50 MW Concentrated Solar Power tower EPC bid reopened overseas suppliers win over". Retrieved 12 September 2017.
  14. "Aurora: What you should know about Port Augusta's solar power-tower". Retrieved 22 August 2017.
  15. "SolarReserve receives environmental approval 390 MW solar thermal facility storage in Chile". Retrieved 29 August 2017.
  16. "SolarReserve Bids 24-Hour Solar At 6.3 Cents In Chile". Retrieved 29 August 2017.
  17. "Cheap Baseload Solar At Copiapó Gets OK In Chile". Retrieved 1 September 2017.
  18. "Salt, silicon or graphite: energy storage goes beyond lithium ion batteries". Retrieved 1 September 2017.
  19. "Commercializing Standalone Thermal Energy Storage". Retrieved 1 September 2017.
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