We have had a number of Arduino dataloggers deployed for a couple years now. The first ones were based on the Arduino Pro boards and a datalogger shield from Adafruit. Our newest version is based on the Seeeduino Stalker board. It’s handy because it has a built-in real time clock (RTC), solar charging circuitry, a microSD memory card slot, and an XBee radio socket. On top of the Stalker board is a homemade shield with circuitry to interface with various sensors (usually pressure transducers and soil moisture probes). We put the boards and a battery inside a clear Pelican 1050 case, along with a solar panel, and mount them to a bracket that can be angled for proper sun exposure. The solar panels keep the batteries fully charged, and the radio modules can transmit with a small wire antenna inside the case, or an external antenna using a panel-mount jack.