Solis (knee) will begin a rehab assignment for High-A Potomac on Friday, Kan Kolko of MASN reports.
The 27-year-old left-hander is having a terrific year for the Nationals, posting a 2.43 ERA with 34 strikeouts in 29.2 innings. If Solis comes out of his rehab appearance with no setbacks, he could rejoin the Nationals rotation at some point next week.