I am trying to temporarily fence a few pastures at the back of my farm so I can make use of the grass since the perimeter fence is lacking. My group of heifers are trained to one strand of poly tape but I'm going to add another strand in these pastures just to be safe. The first pasture I am doing will be around 1500 ft of fence and later on, the second pasture would be 1700 ft, so in all close to 3/4 mile. It has to be a solar charger and I would like to buy one strong enough to handle both pastures. I don't have a fortune to spend but I also don't want to cheap out on something that won't get the job done. How many joules should it need? I am pretty good about keeping fence clean. Thanks for any input.