ARLINGTON — A pilot program offering bite-sized solar investments in Snohomish County filled up in less than a month.

The Snohomish County Public Utility District’s Community Solar program allows homeowners and apartment-dwellers alike to buy into solar energy generated in Arlington. It lets those who can’t afford their own rooftop solar unit, don’t have an adequate roof or live in rented housing to support the development of solar power.

PUD customers could purchase units from a 2-acre solar panel array just west of the Arlington Municipal Airport, in the Arlington-Marysville Manufacturing Industrial Center. Each unit consists of one-fifth of a solar panel and costs $120.

The units went up for sale on Earth Day, April 22, and were all spoken for by May 15. Sales won’t be finalized for 90 days, so program manager Suzy Oversvee encourages anyone who is interested to still submit an application, which is free.

There is currently a 50-person wait list.

More than 500 PUD customers reserved all 7,290 units available.

Their investment will be regained in roughly eight years through rebates on PUD bills and state clean energy incentives. For each unit, the annual savings would total $16.50 — $4.50 in bill credits and $12 in state reimbursement.

The return over the entirety of the 20-year project would be $186 for one unit. For 130 units, the return would be $24,180.

More than a dozen customers have reserved 130 units, the maximum number allowed.

Despite the program’s popularity, Oversvee said it’s unclear if the PUD will build more units to meet demand. The funding that made Community Solar possible won’t be available again.

“We are currently on a waiting list for a future funds if other projects in the state are not built,” she said in an email. “This makes it difficult to plan a project similar to the Arlington project.”

Ten percent of the panels were set aside for a low-income program. Oversvee said more details on that will be available later this summer.

Julia-Grace Sanders: 425-339-3439; jgsanders@heraldnet.com.