Your Y2 Camera comes with a solar panel that includes a lifetime warranty. That lfetime warranty doesn't cover damage caused by animals, humans, or natural disasters (unless you're on the Outfitter plan, in which case, we've got you covered there too). 
You don't ever need to buy one of these solar panels unless a) you aren't on the Outfitter plan and b) your solar panel fails as a result of animal damage or a natural disaster.