Powering Strong Communities

Heartland develops web-based renewable energy calculator with DEED internships

Heartland Consumers Power District in South Dakota has developed a web-based renewable energy calculator using Demonstration of Energy & Efficiency Developments (DEED) internships from the American Public Power Association.

Heartland customers can use the calculator to determine the costs and benefits of installing a renewable energy facility, particularly a solar power array.

In 2019, Heartland initially developed this solar power calculator using a prior DEED internship for funding. Then, in 2020, the utility applied for and won another DEED internship that was used to make a more user friendly version of the original calculator.

Though it was functional and ran well, the original calculator ran on an Excel spreadsheet and used custom macros. Instead, Heartland wanted a version of the calculator that could run with a modern programming language like C# and could be used on any device with a browser such as a tablet or smart phone.

Heartland used its DEED internship to help fund a summer intern, John Kirkvold, a computer science major at South Dakota State University, who wrote the code for the new calculator.

The updated calculator uses data on solar power production from behind-the-meter installations while taking into account weather conditions as well as changing market prices. The calculator also takes into account state regulations that allow customers to sell solar output back to a utility, i.e., net metering. In states without net metering, the calculator uses avoided cost values to determine sell-back values.

After factoring in those variables, the calculator shows the user annual savings in payback time in years it would take a customer to recoup the cost of installing a solar array on their property.

The calculator has assumptions built into it based on the user’s location, which need to be updated periodically. Using a web interface ensures that the latest data is always available to the user.

The aim in designing the calculator was to allow customers to calculate the savings on their annual electric bill, as well as the annual cost to the utility and to the wholesale power entity.

The project also included making data displayed in Heartland’s lobby web functional and able to update automatically, particularly information on Heartland’s resources and generation.