Thanks for the details,
correct, Actions have changed during the review process so lets solve them step by step
First
Script execution of rule with UID ‘037_Solcast-1’ failed: An error occurred during the script execution: Could not invoke method: org.openhab.binding.solarforecast.internal.actions.SolarForecastActions.getPower(org.openhab.core.thing.binding.ThingActions,java.time.Instant,java.lang.String) on instance: null in 037_Solcast
Please assure solarforecastActions isn’t null, Maybe you’ve to restart your system with clean-cache
Second
You’ve to provide an Instant timestamp to get power
var hourPlusOnePowerState = solarforecastActions.getPower(ZonedDateTime.now.plusHours(1).toInstant)
After these changes it’s going to work