Control system enables grid flexibility by turning homes smart

Researchers at Pacific Northwest National Laboratory (PNNL) have developed a control system to enable homes to provide flexibility to the grid.

The system effectively transforms existing home heating and cooling units and hot water heaters into smart appliances that can manage their electricity use in ways that help the grid coordinate supply and demand, according to a statement.

In the US the system could benefit an estimated 120 million homes. In particular, it is intended for homes where residents do not want or are unable to afford smart appliances and it is retrofittable.

“From the beginning, our goal has been to develop a solution that’s inexpensive, simple to install and use and puts residents in charge of its operation,” said Michael Brambley, staff scientist at PNNL, who leads control system development.

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“In return for helping the grid, households must receive an incentive, such as a more favourable electricity rate.”

In developing the control system, the researchers focused on four appliances in existing homes – electric resistance furnaces, electric resistance water heaters, heat pumps and air conditioners.

In testing, the hot water heater and air conditioning results were found to be particularly promising.

For water heaters, the control system demonstrated the potential to achieve electricity demand reductions from 34 to 83% over seven hours, depending on hot water usage levels.

Air conditioners were helped to maintain cool temperatures and decrease electricity consumption. In one example, electricity demand was reduced up to 46% during four-hour tests in which cooling was sustained within a three-degree range considered acceptable to occupants.

This was based on a 20-degree difference between indoor and outdoor temperatures and reductions should be greater for larger temperature differences.

Electric furnace tests also yielded demand reductions of 25%. By having the control automatically preheat the home by three degrees above the usual thermostat setting right before a peak grid period, the reduction should be increased to nearly 46% over a four-hour span.

Partners in the development included smart technology firms ecobee and Shifted Energy as well as the University of Oklahoma.

In the next step, the project team plan to prepare the control system for deployment in occupied homes.

In the US, homes use more than one-third of the nation’s electricity. Thus, connected homes are expected to play a key role in the drive for decarbonisation with the flexibility they can provide to the grid.