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PV Output Variability, The Sheep in Wolf’s Clothing

On a recent Get Some Sun webinar, our own Kelly Foley was joined by Thomas Hoff of Clean Power Research and Dr Richard Perez of SUNY–Albany discussing their cutting-edge research on PV output variability and its impact on the grid. Full video of the presentation is available here.

It’s an issue that’s becoming increasingly critical as grid operators and utilities plan for high levels of PV penetration. Unlike the fossil fuel generators around which our existing energy infrastructure has been designed, solar generation fuel is inherently variable. The sun rises and sets. Clouds happen. This mismatch between the renewable energy resources being integrated onto the grid and the models built to plan for new generation has significant implications. Vote Solar and other renewable advocates are particularly concerned that the old models call for significant levels of new natural gas generation development to shape the variable renewable resources being brought online. You read correctly: more solar would mean more fossil fuel generation. It’s like taking two steps forward and one step back on our nation’s path to renewable energy progress. Not good.

We need to fundamentally shift the planning paradigm to include variable renewables as a non-negotiable piece of our energy mix rather than a risky outlier. At that point, the prospect of integrating high levels of solar and other renewables onto the grid becomes eminently manageable. Read more from Kelly on the topic in her recent Renewable Energy World article.

New research from Thomas Hoff, Dr. Richard Perez and others compellingly demonstrates that current assumptions do indeed overestimate the impacts of solar variability on a balancing-area-wide basis. They present fact-based evidence that a dispersed portfolio of solar electricity systems spread across the balancing area “smoothes” the impact of weather–based solar variability to the point that it can be cost-effectively managed without building heaps of new natural gas power plants. In short, PV output variability really is the sheep in wolf’s clothing of grid planning.

Vote Solar is a non-profit grassroots organization working to fight climate change and foster economic opportunity by bringing solar energy into the mainstream.