Mass. utilities are raising rates in August. Here’s who’s affected.

Many — but not most — Massachusetts residents can expect to pay a little more for electricity starting Aug. 1.

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That’s when the state’s electric utilities, including National Grid, Eversource, and Unitil, reset their “supply rate” for the next six months. That’s the wholesale cost that the utility pays for electricity, a cost that is passed on to consumers.

Right now, the three utilities are charging their customers around 15 to 16 cents per kilowatt-hour; in August that rises to around 17 to 18 cents. With the typical household using about 600 kilowatt-hours a month, customers can expect their monthly bills to rise about $10.

But the majority of utility customers don’t pay the official supply rate. For instance, only 31 percent of National Grid customers will be affected by the price hike, only 36 percent of Eversource customers in western Massachusetts, and only 15 percent in eastern Massachusetts, which includes Boston.

Why so few? Because in Massachusetts, utilities don’t generate electricity; they just distribute it. A host of power generation companies sell electricity to the utilities, under contracts that get re-negotiated twice a year, in February and August.

Boston and many other cities have set up municipal aggregation programs, which let cities negotiate prices with one or more electric suppliers, much as the utilities do. But the cities generally make better deals.

For instance, Boston’s Community Choice plan charges as little as 13.6 cents per kilowatt-hour, compared to the 15.6 cents now charged to Boston customers by Eversource, and the 17.3 cents it will charge starting Aug. 1. Also, the Community Choice rate is locked in until December 2027. The city estimates that customers enrolled in the plan save around $200 per year.

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According to data from the state’s Department of Energy Resources, more than half of Massachusetts electric customers are signed up with a municipal power program, so the August rate hike won’t affect them. People in cities that offer such plans are signed up automatically when they activate their electric service. The Department of Public Utilities runs a website with a list of communities that offer this lower-cost option.

Another 25 percent of Massachusetts electric customers won’t be affected by the August rate hikes, because they buy power directly from electricity retailers. At the state’s Energy Switch website, it’s easy to find alternative power suppliers that charge consumers a penny or two less than the standard electric company rate.

But it’s also easy to get scammed by these alternative suppliers. Some have been accused of switching customers onto their networks without permission, or raising rates sharply and without warning after having promised a much lower price.

A report from the state attorney general’s office estimates that customers who switched to alternative services have paid $738.7 million more over the past decade than if they stayed on standard utility service.

If she had her way, Governor Maura Healey would ban these companies from selling direct to consumers. Language in an energy regulation bill that recently passed the state Senate doesn’t go this far, but would impose a variety of new rules to prevent many common abuses. The bill is currently under negotiation with members of the State House of Representatives, so its final form remains uncertain.

But one thing’s for sure: Even with the state’s competitive marketplace, electric service in Massachusetts is brutally expensive. The direct cost of the electricity itself is only part of the cost. For many consumers, delivering the electricity to the home costs even more. Add in taxes and other fees, and Massachusetts residents pay the fourth-highest electric bills in the US, trailing only Hawaii, California, and Connecticut.

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