May 14, 2022

Cellphone-sized device automatically adjusts a home’s energy use to save money

A cellphone-sized device automatically adjusts a home’s energy consumption up or down to save consumers money and increase the resilience of the power grid.

The effects of climate change are pushing power grids around the world to their limits. Last year, unprecedented cold weather caused Texas residents to turn up their thermostats, which overwhelmed the power grid and caused power outages lasting days. And in California, the power goes out before there is a strong possibility of a fire.

To combat vulnerabilities in the power grid and reduce the use of non-renewable energy sources, researchers at the Department of Energy’s SLAC National Accelerator Laboratory have developed technology that automatically adjusts the power consumption of a home in response to price fluctuations that are established by real-time market demand.

The technology, called Transactive Energy Service System or TESS, also moves electricity across the grid to where it is needed most. This increases the resilience of the network and saves both consumers and the utility company money.

TESS was installed in four homes last month for the system’s first residential test. It will be installed in hundreds of homes across the Northeast United States over the next two years. The people who live in the homes where the trials are taking place are in economically disadvantaged areas to show how TESS is a cheap and effective way to ensure everyone has equal access to electricity.

SLAC transactional energy service system

Small enough to fit in your hand, this device adjusts a home’s energy consumption up or down in response to fluctuations in energy prices that are established by real-time market demand. The Transactive Energy Service System (TESS) is currently being tested in four Colorado homes and is expected to be installed in hundreds more homes over the next two years, with the goal of saving consumers and utilities money while making the electrical network more resilient. TESS was developed by the Grid Integration Systems and Mobility (GISMo) laboratory at SLAC. Credit: Holy Cross Energy

Data coordination in the cloud

The key to making the system work is for consumers to be in control, setting the price at which they are willing to reduce their energy consumption and the price at which they are willing to resell the energy they generate from solar panels or other sources in the network, explains Dave Chassin, group leader of the Grid Integration Systems and Mobility (GISMo) laboratory at SLAC and principal investigator of the TESS project.

A smartphone-sized device monitors the home’s electricity consumption based on energy prices that are evaluated and recalculated every five minutes based on market energy demands. TESS only monitors devices that are flexible in their electricity use – things like a thermostat or a refrigerator that don’t need to be on all the time to perform their function. (A light bulb, on the other hand, is not flexible, as it must be turned on exactly when you want it to be.)

The TESS device tells the utility company how much prices need to increase before the consumer is willing to reduce their consumption, and at what price they would be willing to increase their contribution of renewable energy to the grid. When the price of electricity changes, TESS automatically changes the amount of consumption on behalf of the consumer so as to reduce their cost and maximize their income. All this information is exchanged through a cloud-based platform.

Installation of TESS solar panels

Workers install solar panels on a home in Basalt, Colorado, which is part of a test site for the Transactive Energy Service System (TESS), which adjusts a home’s energy usage up or down based on real-time energy market prices. SLAC’s GISMo lab installed the devices in four state-of-the-art homes built by Habitat for Humanity, electric utility cooperative Holy Cross Energy and other local partners. They are part of a net-zero, all-electric affordable housing complex for teachers and other local workers. Credit: Holy Cross Energy

With TESS, the electricity company does not determine the price of electricity. It’s based purely on supply and demand, and is therefore “clearly the effective price – the correct price,” says Chassin. “The idea is that it will enable utilities to fundamentally change the way they operate to focus more on customer service.”

Consumers who have TESS devices in their homes can also choose to be paid more for the electricity they generate and contribute to the grid and pay less for the electricity they consume, Chassin explained. The fact that the system is fully automated and reacts to price changes as they occur makes it unique in the market.

Putting TESS to the test

TESS researchers are partnering with Holy Cross Energy (HCE), an electric utility cooperative, to deploy TESS devices in December to four homes in Basalt, Colorado, about 180 miles west of Denver. These state-of-the-art homes were built by Habitat for Humanity, HCE and other local partners as part of a zero-electricity affordable housing complex for teachers and other local workers. The plan is to put TESS to the test during the winter heating season, when energy consumption peaks on the HCE system.


One of four homes in Basalt, Colorado testing the Transactive Energy Service System (TESS), which was developed by SLAC’s GISMo lab as a way to save money for consumers and utilities electricity utilities while increasing the use of renewables and making the grid more resilient. The homes were built by Habitat for Humanity, electric utility cooperative Holy Cross Energy and other local partners as part of a net-zero, all-electric, affordable housing complex for teachers and other local workers. . Credit: Holy Cross Energy

“We’re excited to provide the TESS project with a real-world testbed that can now take what we’ve learned in the lab and move it forward,” said Bryan Hannegan, CEO of Holy Cross Energy and former lab associate. director of the DOE’s National Renewable Energy Laboratory. “We see a lot of value and benefits for our business and for our consumers by being at the forefront of innovation.”

Having co-founded the DOE’s Grid Modernization Initiative during his NREL days, Hannegan is familiar with the development of the TESS platform and says he believes TESS or a similar approach can help Holy Cross Energy achieve its ambitious goal of have a 100% carbon-free power supply by 2030 and have net zero or better greenhouse gas emissions across their business by 2035.

Make clean energy accessible to all

The next stage in the development of TESS is to deploy the devices to several hundred homes in three rural communities in Maine and New Hampshire as part of the DOE’s Connected Communities program. For this project, he is partnering with the Post Road Foundation, an Oakland-based nonprofit organization that helps underserved communities build sustainable infrastructure to support high-speed internet and power grid modernization.

TESS researchers plan to test the extent to which energy storage can be integrated into the system to increase its resilience and reliability, especially in an emergency. During this time, the foundation will work to identify the benefits of TESS for the communities where it is deployed and find ways to fund the project in underserved areas.

“When it comes to inequality, we focus on rural areas — areas where energy costs can be a significant expense for households,” says Seth Hoedl, president and chief scientific officer of Post Road. For these rural and underserved consumers, installing TESS in their homes would make switching from oil or propane to electric appliances more cost-effective, Hoedl says. People who install renewable energy devices in their homes will benefit even more from TESS’ reduced energy costs and the ability to sell the excess energy produced by these renewables.

When considering options to help the planet, consumers often feel like they have to choose between improving their standard of living or doing what’s best for the environment, Hoedl says. TESS not only provides a way to achieve both goals, but also costs relatively little because it doesn’t require a significant amount of new infrastructure to be built, he says: “It can have really financial and operational benefits. and the same climate benefits as building a large renewable energy plant.

Chassin says, “Things are going to change quite quickly over the next 10 to 20 years, and technologies like TESS are going to be part of the suite of climate change solutions that utilities are going to start rolling out. Their customers will have more interesting and useful opportunities to participate in solving the problem. »

Funding for TESS comes from the DOE’s Office of Electricity. Funding for TESS Connected Communities comes from the DOE’s Office of Building Technologies within the Office of Energy Efficiency and Renewable Energy.