San Francisco Mayor London Breed is expected to set an ambitious goal Thursday of adding 1,000 beds for homeless people by the end of 2020, in part by opening three new shelters.

The addition would greatly expand the current supply of 2,500 beds, most of which are in emergency shelters. Beds are also available at Navigation Centers and in transitional housing.

Breed wants half of the new beds to be available by the summer.

As the city grapples with a persistent homelessness epidemic, Breed said that adding shelter beds was among her top priorities in the effort to get people off the streets.

“If we want to see a difference, we need places for people to go,” Breed said. “We can’t just leave people out on the street. We need options. Letting people sleep in the streets because we don’t have enough shelter beds, that’s a problem.”

Breed’s plan involves opening three new shelters to accommodate 700 people — with each shelter offering between 200 and 250 beds. City officials are still working to find locations for the new shelters. Breed is calling the new shelters “SAFE” facilities — short for “shelter and access for everyone.”

Similar to the city’s Navigation Centers, Breed wants the new facilities to feature more accommodations than most traditional shelters. The new facilities would be open around the clock, for example, allow partners to stay together, and provide storage for belongings so people can come and go from the shelter more freely.

There would also be some services available on-site, but not to the extent currently offered at Navigation Centers.

The remaining 300 beds would come from the opening of new Navigation Centers, several of which are nearly ready. The city expects to open the 128-bed Bayshore Navigation Center this month. Another, at Fifth and Bryant streets, is scheduled to open in November.

Once the new beds are available, “We will be in a much better place to ensure that all of our very high priority clients, who are often the sickest and longest-term homeless, have access to a bed until they can get housed,” said Jeff Kositsky, director of the city’s Department of Homelessness and Supportive Housing.

Breed said she’ll find the money to pay for the new shelters and beds in the upcoming two-year budget cycle. She’s also willing to consider shifting existing funds away from less successful homelessness programs that she said aren’t delivering results.

Dominic Fracassa is a San Francisco Chronicle staff writer. Email: dfracassa@sfchronicle.com Twitter: @dominicfracassa