UPDADTE (2019-08-14): The Witty Pi 2 accessory has proven unreliable. It’s not recommended, but still supported for those who are succeeding with it. See here for more details.
Old Announcement: The Witty Pi hardware board is now supported to save power when you dont’ want to record.
Power consumption has always been the biggest limitation of the Solo, and this alleviates that by turning off the Raspberry Pi when recording is not required.
More details of how to get it working are here.