A comparative study of high renewables penetration electricity grids

Electricity grids are transforming as renewables proliferate, yet operational concerns due to fluctuations in renewables sources could limit the ultimate potential for high penetrations of renewables. In this paper, we compare three electricity grids - California, Germany, and Ontario - studying the effects of relative cost of solar and wind generation on the selection of the renewables mix, and examine the resulting excess generation. We then observe the effects of the renewables mix and the use of baseload energy generation on the limits to renewables penetration, quantifying what proportion of delivered energy can be provided by renewables. Our study shows that the optimal renewables mix, from the perspective of minimizing total cost of generation, is highly dependent on the relative costs of technology, and that above a certain penetration rate, different for each grid, the optimal mix must contain both solar and wind generation.