Distributed Energy Resources

Heartland uses DEED grant to develop solar calculator

Heartland Consumers Power District in Madison, S.D., has developed a solar power calculator for its customers using an American Public Power Association Demonstration of Energy and Efficiency Developments (DEED) program grant.

There are already calculators available to estimate the costs and benefits of solar power, but they tend to be generic and to use general assumptions. “We were looking for something customized for our customers’ locations and regulations,” Adam Graff, director of power supply at Heartland, said.

Heartland is a wholesale utility that serves municipalities and entities in South Dakota, Minnesota, Iowa, Kansas, and Nebraska.

With behind-the-meter renewable generation becoming more popular, Heartland was receiving a growing number of requests from its customers seeking guidance on the costs and benefits of potential solar power installations.

Those requests mostly took two forms, large solar farms being developed by third parties or homeowners interested in installing solar panels on their homes.

In the first case, Heartland needed to have a way to assess large solar projects proposed by developers under the Public Utility Regulatory Policies Act (PURPA).

Ordinarily a distribution utility would be required to buy the output of a solar qualifying facility (QF) under PURPA, but that could prove to be a burden for the distribution utilities in Heartland’s territory that serve small towns or municipalities.

In March 2016, the Federal Energy Regulatory Commission granted a waiver filed by Heartland, allowing the wholesale utility to step in as the purchaser of power from a QF for 22 of the utility’s 28 customers in South Dakota, Iowa and Minnesota.

Since it bears the obligation to purchase power directly from QFs, Heartland realized it needed an accurate calculator to determine the effect any new generation would have on its customer base as a whole.

In the second case, vendors of solar systems were approaching end-users who would turn to their local utility for advice. The local distribution utility, in turn, would turn to Heartland. Both Heartland and the local utility wanted to be sure they were providing the end-user with accurate information and a realistic picture of the ultimate possible benefits of solar installation.

From an operational point of view, the solar calculator that Heartland developed using the DEED grant has “turned out pretty good,” Graff said. The calculator has two different versions. Graff said a residential customer using the retail version used it to assess a potential installation and found the numbers were marginally different that the numbers the vendor was giving. That customer is still moving ahead with the project, but is now trying to “right size” it to better match their load, he said.

The DEED grant was awarded May 5 and the project ran from May 15 to Aug. 20. It took the form of a scholarship, which was awarded to Peter Choudek, a student at St. Cloud State University in St. Cloud, Minn. Choudek was an intern at Heartland this summer. The DEED grant helped Heartland pay for his internship.

The calculators – there is one for residential and one for wholesale projects – allow users to enter data such as state of residence, electricity cost, home electric usage, solar array size and budget and then provides the user with estimated energy savings, cost savings, and potential payback period.

The results are customized for the individual user based on their inputs and incorporate state and federal laws and applicable tax credits. In addition, a number of assumed average inputs, such as electricity cost, electric usage, solar cost, unique to the individual’s location are included in the calculator. The calculator also incorporates all data inputs into an algorithm that estimates the financial impact of a solar installation on a retail utility.

Choudek says it took about two months for him to build the calculator, which was the first energy app he has worked on. He based his work on other online solar calculators, but customized it for local regulations, such as the fact that Minnesota has net metering for solar power and South Dakota does not.

In addition to local regulations, the calculator also built in applicable regulations for all 50 states. The focus, going into the DEED effort, Graff said, was to create something that could be used by utilities anywhere in the country.

Choudek was also given access to a monitoring system for a solar array at one of Heartland’s customer communities, which helped determine production of different sized arrays. “The data gathered was helpful in getting production curves for different weather patterns,” Graff said.

Graff said Heartland is now interested in taking the project to the “next level” with the roll-out of a web-based version.

The current calculator uses Microsoft’s Excel spreadsheet application. A lot of work has to be done before that happens, however. That could be a project for another intern, possibly in the summer of 2020, Graff said.

For additional information about the DEED program, click here.