More than 10,000 Valley businesses and residences were still without power Friday afternoon, a day after heavy winds toppled trees and plunged large parts of the city into darkness. As of 3:30 p.m. Friday, outages were mostly concentrated in the mid-Valley, affecting 17,000 customers in Pacoima, 3,600 in Sherman Oaks, 606 in North Hollywood and 817 in Van Nuys, said Department of Water and Power spokeswoman Kim Hughes. Citywide, more than 47,000 DWP customers were without electricity Friday afternoon, Hughes said, down from the initial 109,000 Thursday evening. About 300 DWP technicians are working 16-hour shifts to bring power back online, although it could take until Sunday evening for power to return citywide, the DWP said. “We’re still working as quickly and diligently as we can,” Hughes said. “We’ve knocked it down quite a bit.” The gusts, which reached 50 mph in some places, also knocked out traffic signals. Downed power lines also sparked a blaze in Palmdale that scorched about 20 acres before flames were knocked down late Thursday.