HARRISBURG — Starting the dishwasher, plugging in a hair-dryer or flicking on a light switch will register with utilities almost instantly when their customers are monitored by state-of-the-art electric meters. So-called “smart meters” represent about four in 10 electric meters installed across the state, and utilities appear to be running ahead of schedule in introducing them before a 2023 deadline. Upgraded meters that give electricity companies and their customers real-time information about energy use are long overdue, regulators say. “Power is still billed the way it was 100 years ago,” said Nils Hagen-Frederiksen, spokesman for the state’s Public Utility Commission. But consumer advocates cite downsides — including higher bills for some households. Others complain that customers shouldn’t be forced to accept the technology, even though it’s required by a 2008 state energy conservation law. Pennsylvania is slightly behind the curve in implementing smart meters. The meters are installed in more than 90 percent of homes in Nevada and Maine, according to a separate study this spring. More than half of the homes in at least 16 states have them. Pennsylvania’s progress is localized, with three of four smart meters installed in Philadelphia and its suburbs. In western Pennsylvania, PennPower has replaced old meters with the new technology, as well. In most of the state, the rollout begins this summer and continues during the next four years. The technology itself won’t translate into higher energy bills, say consumer advocates, lawmakers and industry officials. But it does allow utilities to charge based on the time of day, with higher rates for running appliances or the air conditioning when demand is greatest.