Selecting an energizer.  Energizers are the heart of electric fencing systems and are NOT a component that you should try to “save” money on.  A low-cost energizer often costs more in terms future repairs and replacements and possibly loose livestock.  If electrical service is available, plug in energizers are considerably more powerful and offer the best value in terms of cost to power ratio.  For remote areas, solar or battery powered energizers are viable alternatives for smaller acreages.  Power comparisons of energizers should be done using “stored energy” which is measured in joules.     ~ Dr. Chris Teutsch