HALLOWELL — Around two dozen solar power proponents rallied outside the Maine Public Utility Commission office Wednesday to protest proposed electricity rate changes they say will discourage individuals from investing in renewable energy sources.

Most rally attendees donned yellow “Solar for ME” t-shirts handed out by members of out-of-state advocacy groups before filing into the building for the public hearing on the proposed changes.

Advocates and users of renewable energy — from homeowners with solar panels to larger institutions such as private colleges and the Brunswick Landing business park — have objected to a portion of Central Maine Power Co.’s proposed new rate plan that would levy a charge for customers who generate their own power.

CMP also is trying to raise the fixed monthly fees it charges residential and small business customers, while lowering the variable price charged for electricity.

Both the standby charge for customers using renewable energy sources and the changes to the fixed and variable fees would harm current and future users of solar power, said Fred Greenhalgh from Revision Energy, a renewable energy company with offices in Maine and New Hampshire.

Greenhalgh, who spoke at the rally before the PUC public hearing, said the changes would be unfair to people who have already invested in solar power or other renewable sources and would discourage people from using renewable sources by making the investment less economically feasible.

However, CMP says the standby charges for self-generating users and the fixed and variable charge changes are needed to better reflect the cost of providing and maintaining services to the company’s 610,000 customers.

“This is really a question of fairness for all customers,” said Gail Rice, a CMP spokeswoman, by phone on Wednesday. “When customers self-generate, our costs to serve them does not change, and when they pay less to CMP for their delivery service, other customers have to pay more.”

She said it costs CMP the same to maintain the distribution lines to customers generating their own electricity with solar panels or wind turbines as it does for customers relying entirely on electricity from CMP.

The proposals are being reviewed by the PUC as part of the utility company’s new five-year rate plan that will go through 2019. If approved, the new rates will go into effect July 1, Rice said.

Organizers of Wednesday’s rally are holding another protest before the next PUC public hearing on Thursday at 7 p.m. at the University of Southern Maine in Portland.

An attendee at the public hearing in Hallowell, John Williams, 60, said he and his wife use solar power for their home in Lincolnville and use the electricity generated to charge their Chevy Volt.

He said he thinks CMP should increase the usage charge for electricity instead of the fixed monthly fee.

“What they want to do is gonna discourage people from putting solar on their houses and that’s not the right way to go,” Williams said.

About 1,350 CMP customers have installed self-generating power sources, largely solar, Rice said. That’s up from around 1,000 when CMP filed its plan last May, she said.

Those customers still rely on CMP to provide electricity when they can’t generate enough themselves, and the standby rate would be a way to charge those self-generating customers even though they aren’t buying electricity all the time.

The changes proposed by the electricity distribution company are part of a transition to put more of an emphasis on the fixed costs in response to flat or declining overall consumption, Rice said

The proposed monthly standby charge is $24.83, about $12 higher than the fixed monthly fee for residential customers, Rice said.

With the fixed and variable fee changes, a typical residential customer using around 525 kilowatt hours a month would see $1 to $2 increases in their monthly bills, according to Rice. Higher-use customers would see smaller increases, and customers using 800 kWh per month or more will see their monthly bills decrease, she said.

But opponents of the changes say people shouldn’t be given incentive to use more electricity.

“We all need to be reducing our electric use as much as reasonable and coming to cleaner sources,” Greenhalgh said. “And the policy basically encourages the exact opposite.”

Paul Koenig — 621-5663 pkoenig@centralmaine.com Twitter: @paul_koenig