SALT LAKE CITY -- Solar industry advocates rallied at the Utah State Capitol this week to oppose a bill known as STEP.

Rocky Mountain Power says the Sustainable Transportation and Energy Plan will improve Utah’s air quality, but others say the language in Senate Bill 115 doesn't support solar.

Brandy Smith, a communication coordinator for the group Utah Clean energy, said they got word of a last-minute amendment to SB 115 on Thursday.

“Right away we started getting calls from solar home owners, the solar industry saying, ‘Oh my goodness, this is a nightmare. This is going to kill solar in Utah,’” Smith told the crowd at the Capitol.

Advocates said the language in the bill changes the process for evaluating the benefits of rooftop solar.

“Some of the lines of this bill regarding net metering tariffs create an unfair process, where Rocky Mountain Power can ignore the economic benefits of solar,” said Kelly Curtis, CEO of Solaroo.

These solar power advocates claim that if the bill passes, it will likely result in a rate hike for all solar customers.

“All of our homes and businesses that have solar on their roofs actually reduce costs for all rate payers,” said Sophie Hayes, a staff attorney for Utah Clean Energy. “And so by increasing their rates, you’re actually punishing customers who potentially reduce rates for all customers.”

More than 2,600 people are employed in Utah’s solar industry, but Hayes said this bill could change that.

“The changes to this bill could have dramatic and devastating impacts on those jobs,” Hayes said.

Paul Murphy, Spokesman for Rocky Mountain Power, released a statement, saying in part: “The bill allows the Public Service Commission to continue its work to determine what a fair rate is for rooftop solar customers.”

Murphy said this would happen with or without this legislation, and added that: “environmentalists should be cheering for STEP instead of protesting it because it will help improve the air and increase the use of renewable energy."

Click here for more on RMP’s position on STEP.

Utah Clean Energy is asking the legislature to amend the bill to omit all net metering language and policy changes.

“It’s really important that the senators get this bill right, and we’re willing to work with them and we hope that they will give this legislation a really critical eye,” Hayes said.