Power’s out, but I’ve got solar panels so I’ll be all set, right?
During a power outage, the solar inverters that connect homes to the grid get powered down for safety. But a team of engineers at the University of California San Diego is working to change this.
The team has developed an algorithm that would enable homes to utilize and share renewable energy sources during outages. The method, which works by prioritizing power distribution and strategically disconnecting inverters from the grid, would also improve system reliability by 25 to 35 percent.
"We were inspired to start investigating a way to use renewable power during outages after Hurricane Sandy affected eight million people on the East Coast and left some without power for up to two weeks," said Abdulelah H. Habib, a Ph.D. candidate in mechanical engineering and first author of a paper on the research presented at the American Control Conference in Seattle.
Power outages are a big deal: Every year, seven million customers experience power outages. Outages that last more than five to 10 minutes cost customers more than $80 billion each year.
Inside the Algorithm
The researchers’ equations take into account a number of factors:
- forecasts for solar and wind power generation;
- how much energy storage is available, including electric vehicles, batteries, etc.;
- the amount of energy residents are projected to use; and
- the amount of energy a cluster of homes can generate.
The algorithm can also be programmed to include a priority function, based on given parameters—such as giving priority to customers who use life support equipment.
Researchers also investigated which energy storage configuration would work best with their algorithm. While having storage systems in each home leads to optimal performance, employing a community-based system dramatically cuts costs.
"Houses connected together are much more resilient during outages," said Raymond de Callafon, a professor of mechanical engineering and one of the paper’s senior authors. "They're also more resilient to price fluctuations. They can do a much better job at sharing resources, and it benefits every house."
Although the algorithm works with existing technology, additional resources would be required for full deployment. These include:
- equipping each home with circuit breakers that can be remotely controlled;
- installing advanced communications methods that allow power systems in a residential cluster to talk to one another; and
- equipping each home with “grid forming” inverters that can connect to one another (as opposed to the standard “grid following” devices, which can connect only to the grid).
In addition, regulations would need to change: in most states, residential home owners are currently not allowed to sell power to other home owners. The researchers point out, however, that businesses without backup generators would be able to take advantage of the algorithm’s design.