The five biggest challenges that utility-scale solar pose to the grid
1) Variability:Power plants that run on fuel (along with some hydro and geothermal plants) can be ramped up and down on command. But solar plants produce power only when the sun is there is sunshine. Grid operators do not control solar plants, they accommodate it, which requires some flexibility of the network.
2) Uncertainty: The output of solar plants cannot be predicted accurately in day-ahead and day-of forecasts, so grid operators have to keep excess reserve running just in case.
3) Location-specificity: Sun are stronger (and thus more economical) in some places than in others — and not always in places that have the necessary transmission infrastructure to get the power to where it’s needed.
4) Nonsynchronous generation: Conventional generators provide voltage support and frequency control to the grid. Solar generators can too, potentially, but it’s an additional capital investment.
5) Low capacity factor: Solar plants only run when sun cooperates. The average capacity factor — production relative to potential — for utility-scale solar PV was around 28 percent. The average capacity factor of nuclear power was 92 percent; those plants are almost always producing power. Because of the low capacity factor of solar, conventional plants are needed to take up the slack, but because of the high output of solar in peak hours, conventional plants sometimes don’t get to run as often as needed to recover costs.
There are solutions for integrating solar into the grid, they may include the following:
• Improved planning and coordination
• Flexible rules and markets
• Flexible demand and storage
• Flexible conventional generation
• Interconnected transmission networks