Ontario hydro customers are in for a shock as the price of electricity gets set to rise yet again.

The Ontario Energy Board (OEB) announced new time-of-use pricing Monday that jacks up the peak rate to 16.1 cents kWh from 14 cents kWh, effective May 1.

It will be more than twice as expensive to use electricity between 11 a.m. and 5 p.m. on weekdays than at night or on weekends.

A typical household will see a $5.71 or 4.6% jump in their monthly hydro bill based on the new pricing, the OEB says.

Ontario Progressive Conservative MPP John Yakabuski said the figure used by the OEB to estimate the impact on bills is just an average, and many people will see a bigger increase on top of years of rising prices.

Ontario’s hydro rate is the second highest in Canada, behind PEI, and more than most jurisdictions in the United States, he said.

“People are at their wit’s end,” he added. “Every time you turn around, you’re getting hit with another increase.”

As of May 1, time-of-use electricity pricing switches over to summer hours.

Off peak power rates — overnight and on weekends and holidays — rise slightly to 8 cents kWh from 7.7 kWh.

Mid-peak rates also climb to 12.2 cents kWh from 11.4 cents kWh.

“Increased costs from Ontario Power Generation’s (OPG) nuclear and hydro-electric power plants make up about half of this increase. Costs from new generation sources are another driver, representing about one-third of the increase,” a statement says. “The OEB is also introducing a new 2:1 ratio between on- and off-peak prices that will benefit customers who shift their use to the cheapest time period.”

Yakabuski said the “new generation” must refer to the wind turbines sprouting up around the province.

Premier Kathleen Wynne said the new on-peak/off-peak rate differential should encourage conservation which ultimately helps keep bills down.

“The increase that the OEB announced today is not as high as it was projected to be in our long-term energy plan,” Wynne said. “Everything that we are doing in terms of energy prices is an attempt to put that downward pressure on them.”

Ontario Environmental Commissioner Gord Miller has called for a greater difference between off and peak power rates to encourage people to shift their electricity use to a time of day when there is less demand — like at night.

The electricity system would then have to build fewer costly power plants.

However, not everyone can move electricity use to off hours, Yakabuski said.

“If you’re one of those people who runs a mid-day business ... — small little ma and pa restaurant serving the lunch crowd — you have no way of getting out of that peak,” he said. “If you’re a senior suffering from a respiratory disorder that requires you to run air conditioning during the summer months, you’re getting hammered again.”

If the OEB maintains the pattern it has adopted since 2007, hydro prices will increase again in the fall.

The unpopular Debt Retirement Charge disappears from hydro bills as of Jan. 1, but so does the Ontario Clean Energy Benefit that reduces bills by 10%.

HOW TO AVOID A SHOCK

(Or when to run your washing machine, air conditioning and big screen TVs after May 1)

•7 p.m.-7 a.m., weekends and holidays — at 8.1 cents per kwh this is your cheapest (although not cheap) time to use electricity.

•7 a.m.-11 a.m.; 5 p.m.-7 p.m. weekdays — at 12.2 cents per kWh, it’s going to hurt but still less expensive to turn on dishwasher and dryer during these two periods than when peak rates kick in.

•11 a.m.-5 p.m. weekdays — unless you’ve got a money tree in your backyard, try to power down — that electricity costs a shocking $16.1 cents kWh