Millions of people came out to watch the solar eclipse that took a 70-mile path across the United States on Aug. 21 and was 85 percent complete over Toledo.
However, University of Toledo professor of physics and astronomy Randall Ellingson, along with graduate student David Raker, came out to watch the eclipse for a totally different reason.
Ellingson and Raker used data collected from the University of Toledo’s solar panels, both on Main Campus and on Scott Park Campus, to determine just how much energy was lost due to the eclipse.
“The eclipse resulted in a total loss of less than 0.1 percent of our annual energy generation, so while it’s an unusual event on an annual basis, the impact is buried within the noise of our usual weather,” Ellingson said.
The information they gathered was collected using a scientific setup designed in a collaborative effort by then-high school student and current University of Toledo student Roan Martin-Hayden. The computer-controlled system allows them to measure the irradiance, or the power in the sunlight, as well as the current power produced by the array over the day.
The solar panels on Main Campus have a nameplate capacity, or the full-sun sustained output, of 32 kW and generates more than 40,000 kWh of electrical energy in a typical year.
“That’s enough to power almost 5 average US homes,” Ellingson said. “It generates that much electricity each year."
During the eclipse, Ellingson and Raker recorded the data to see just how much of the sun’s energy was blocked, to understand how to predict how much energy is lost and what can be done to remedy this problem.
“We were able to calculate how many kilowatt hours of energy were lost, and we know the actual amount of energy that was generated, so you can add those together and figure out just how much energy would have been generated on that day in the absence of the eclipse,” Ellingson said.
This data is of interest for a project Raker is working on at Scott Park Campus funded through the Pacific Northwest National Lab. The project, led by professor of physics Michael Heben, involves balancing energy supply and demand using the photovoltaic array, a battery storage system, and various buildings’ electrical systems on Scott Park, such as heating and cooling.
"We’re collecting data, and we can control all of the building automation systems over on Scott Park,” Raker said.
According to Raker, the goals include storing some of the energy they get from the Scott Park Campus photovoltaic array, which is around 35 times larger than the R1 building’s array on Main Campus, as well as managing campus building systems to yield a relatively even electrical demand level using solar energy and a battery energy storage system.
“It depends on more than how you generate your power. If you plan to just generate your power like that, then you’ll need a place to store it. You’ll also need to manage the highs and lows,” Raker said.
Using a large battery storage system, as well as the various building loads, the project attempts to “smooth the curve” or to predict accurately the amount of energy needed to run campus daily.
“From the utilities perspective, they are getting a predictable power signal,” Raker said.
The project stores energy on campus, such as in the chiller plant, or by curtailing the use of fans or heaters to shift slightly the amount of power being used at a given time to compensate for irregularities in the energy produced by the sun.
“Do you know where Ohio’s electricity comes from? Most of it comes from coal and natural gas and a little less from nuclear, but increasingly we generate electricity from photovoltaics,” Ellingson said. “So as solar electricity becomes more important to the grid, power companies need to know approximately how much solar electricity is going to be supplied over a given period of time.”
The project makes solar power an easier source of energy and more realistic for places like Ohio, where a consistent and powerful sun is not always an option.
“There's no reason that you shouldn’t be able to get all or most of your power from photovoltaics — there's certainly enough sunlight,” Raker said.
Even though solar energy may not be as economically feasible as other sources today, Raker said the environmental benefits and growing field of photovoltaics make it a viable energy source even for places like Toledo.
“Germany has as much photovoltaic capacity as the entire US, and their solar resource is lower than Toledo’s in terms of the average sunlight intensity,” Ellingson said.