Although solar photovoltaic (PV) panel prices are rapidly dropping, integrating a high quality solar energy into the grid will have added costs, particularly because solar is an intermittent resource with highly variable output and repercussions for transmission grids.
To assess the issue, the US Department of Energy and Nevada’s utility, NV Energy, jointly sponsored a study conducted by Navigant Consulting on what the integration of solar in Nevada will mean for the utility. Download the full study here.
The study found that because solar is an intermittent resource, NV Energy will need 1 MW of additional thermal generating capacity to firm 25 MW of solar PV capacity, and on average, 1 MW per minute of additional ramping capability for 75 MW of PV power.
“If generation cannot ramp up or down quickly enough to respond to variable PV, system upgrades or changes in operations would be required. Even if upgrades are unnecessary, the additional generation required to be on line to meet NERC reliability requirements will generally result in higher costs,” the study says.
Authored by five Navigant consultants, including Eugene Shlatz and Lisa Frantzis, the study considered the impacts of 1042 MW of combined large-scale PV and distributed generation (DG), with each ranging from 5 to 300 MW of generation capacity, in southern Nevada. It did not assess concentrated solar power plants.
Shlatz told Breaking Energy that the study was highly location specific. Though the Nevada study found that rapid cloud cover and the resulting drop in solar generation will be costly for the grid, he said studies in places like Toronto have shown different results. Load patterns, weather patterns, and utility make-up all affect solar output, he said.
“There is no one magic rule of thumb,” he said. He added that storage devices could be helpful in making solar power more predictable, but are also extremely costly, making it unlikely that small developers would consider installing batteries. There are “many technologies out there that can provide additional firmness.” The question remains: Who will pay the additional cost for those technologies?
For more on solar energy storage, see this Breaking Energy interactive infographic.
NV Energy submitted an application to the Public Utilities Commission of Nevada (PUCN) for the study in early 2010 when large amounts of solar projects–both small distributed generation projects and larger utility-scale plants–were being built and developers were requesting interconnection.
Photo Caption: US Senate Majority Leader Harry Reid (D-NV) (right) talks with workers while touring the Copper Mountain Solar Facility April 5, 2010 in Boulder City, Nevada.