Temperature/RH Sensor for Grain Bin

What I would like to do is have on Arduino per grain bin connected via a wireless network in order to get sensor readings. The Arduinos would have to be solar powered. What I'm trying to figure out right now is what parts to use for the sensors.

Here is an example of an existing cable http://www.advancedgrainmanagement.com/media/31281/moisture%20cable.pdf

and some more information here http://advancedgrainmanagement.com/media/31284/stormax.pdf

It looks like the current commercial cables communicate via SMBus, but I'm not sure how if that is the way to go. However, it would be nice to have arduinos setup to work with existing cables.

I have looked at the DHT22 sensor, but I'm not sure if that is really a good option if I'm going to be using 7 sensors on a cable.

Does anyone have a sensor recommendation for this project?