A DS3231 might be what you want. It's an RTC as the DS1307 but has a programmable alarm which then triggers an INT pin which can wake up the Arduino.
You might wanna give the Seeeduino Stalker (V2.1, http://www.seeedstudio.com/wiki/Seeeduino_Stalker_v2.1) a try. It includes an Arduino trimmed for power saving (Atmega 328p running on 8MHz) with a DS3231 (for sleeping/wakeup as well as RTC), an microSD card socket (logging) and a XBEE socket (wireless communication). Everything to control a solar panel and a LiPo battery is also included. A water proof case is also available. I use one of these myself and the only thing you have to change is that you need a USB2Serial adapter to upload your code.