Because renewable energy depends so much on Mother Nature, Tucson Electric Power is partnering with the University of Arizona on sophisticated weather forecasting to predict how solar and wind installations will perform.

The information is crucial for planning purposes as TEP works to maximize its renewable energy portfolio while preserving reliable service for customers, said Nicole Bell, TEP Renewable Energy Forecasting/Trading Analyst.

“We convert various weather models into a renewable energy forecast. Then, we use the forecast to better predict how TEP’s renewable energy systems will perform,” Bell said. “If we know that clouds will roll in at a particular time, we know we will receive less energy from our solar arrays. This allows us to plan and provide reliable service for our customers.”

The forecasting models utilize information from approximately 100 ground-level solar radiance monitors located throughout the Tucson metropolitan area. Cloud movement, wind direction and speed, and additional data are fed into the models to gain the most accurate predictions.

The models look at three different time horizons: long-term, which is up to eight days out; short-term for a one- to two-day outlook; and real-time forecasting for up to three hours out. Each model uses a different combination of data and numerical modeling.

TEP’s partnership with the UA puts it a step ahead of utilities that rely on forecasting from commercial providers. “We have really utilized the skills and talents of our local university,” Bell said.

Weather forecasting is a crucial aspect of managing renewable energy and the grid, said Ted Burhans, TEP Manager of Renewable Energy.

“Solar is an intermittent resource. By having accurate weather forecasts, our grid operators know when they can count on the solar output,” Burhans said. “It’s helpful from a grid reliability and stability standpoint.”