The 220W solar panel is compatible with the 1st generation EcoFlow River Pro as long as the voltage and current of the panel are within the specifications of the River Pro (10-25 V DC, max. 12 A) and an MC4 to XT60 adapter cable is used. The River Pro supports a maximum solar input power of 200W, so the 220W panel is slightly above the rated power, which should be noted. EcoFlow recommends the use of panels with MC4 connection and compliance with the voltage and current limits for safe use.