How about this great little gadget from Horseware……2*3 speakers with a 5.5V solar panel. This will charge an Iphone/Ipad/MP3/MP4/mobile phone. Multi-unit charging choices. The padded unit protects your phone/device around the yard or stable. Great quality amplified sound, perfect for weekends away or for when you are busy on the yard.
Solar charge 25-30 hours
USB charge 4-6 hours