[JT118]

I assume you are considering solar power for the TX board as a whole. (Temp sensor plugs in to TX board). I use a 12v wall plug with long bit of wire. (Cheap and easy, voltage drop isn,t too bad if you are not too far apart and use thick cable) But if you are going the solar route you just need a panel (sized for latitude and weather, big panel in Scotland!)

Panel example,

http://www.ebay.co.uk/itm/Solar-Panels-P...FBxVpPkr3w

Charge controller example,

http://www.ebay.co.uk/itm/10-20-30A-Amp-...eBrKWZCF_w

Battery example,

http://www.ebay.co.uk/itm/12V-220-8Ah-AG...gvj6PDkbKg
 
All matched as you see fit.