Statewide grand jury indicts two in home solar contracting criminal fraud scheme

Dec. 18, 2025 (DENVER) — The statewide grand jury indicted two defendants on 11 counts for allegedly taking payments from clients throughout Colorado to install solar systems on their homes and failing to complete work on the projects, Attorney General Phil Weiser announced today.

According to an August 28, 2025 indictment (PDF), Nathan Billmaier and Scot Birrell, through their company Sopris Solar, solicited and contracted with clients across Colorado, including in Eagle, Park, Prowers, San Miguel, Summit, and Weld counties. The defendants allegedly received customer deposits and then failed to complete work on the projects or provide materials. In all instances, the defendants failed to return the customer’s money for work that was not done.

The state investigation revealed that hundreds of thousands of dollars in customer payments were deposited into a Sopris bank account and then spent for purposes other than for the specific customer’s project. The defendants are accused of using deceptive tactics to commit financial fraud against their customers.

“Colorado law requires that contractors hold collected client funds in trust for the client’s designated project. Failing to do so may lead to criminal theft left charges if a contractor violates this state law,” said Attorney General Weiser. “We’ll continue to hold accountable those who attempt to defraud homeowners of their hard-earned money.”

The defendants are charged with racketeering and conspiracy under the Colorado Organized Crime Control Act, both class two felonies, seven counts various degrees of felony theft, and two counts felony tax evasion. The cases are filed in Jefferson County District Court under case numbers 25CR2138 (Billmaier) and 25CR2137 (Birrell).

The Special Prosecutions Unit in the Criminal Justice Section of the Colorado Department of Law is prosecuting the case.

Birrell is in custody at the Denver Downtown Detention Center. Defendant Billmaier is at-large. The attorney general’s office is asking that anyone with information about his whereabouts to call their local law enforcement agency. Members of the public should not take any action themselves above and beyond contacting their local law enforcement agency to make the report.

A grand jury indictment is a formal accusation that an individual committed a crime under Colorado laws. All defendants are presumed innocent until proven guilty.

See photos of Nathan Billmaier (PNG) and Scot Birrell (PNG).

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Media Contact:
Lawrence Pacheco
Chief Communications Officer
(720) 508-6553 office
lawrence.pacheco@coag.gov