The NRG Symphonie iPack for PV Only contains a 12V rechargeable gel cell battery pack and PV charging circuit in a specially designed weather-tight enclosure. PV panel must be ordered separately. Applications Provides a "Stand-Alone" power solution for the NRG Symphonie Logger when using sensors requiring more power, such as the NRG BP-20 Barometric Pressure Sensor and the NRG RH-5 Relative Humidity Sensor. Features Interfaces directly with the NRG Symphonie Logger by connecting to a DB25 port located on the back of the NRG Symphonie Logger. The iPack and NRG Symphonie Logger are secured to the shelter box via four long screws. Modular approach provides flexibilty as the iPacks can be moved to different sites as new technologies or system requirements evolve. Not sure which iPack you need? See our iPack comparison chart... Note: All NRG Symphonie iPacks are compatible with both Symphonie and SymphoniePLUS data loggers.