However, the stove and the vent pipe may not be guaranteed if you are not using wood pellets (I think the manual for the stove states that it can burn standard or premium grade wood pellets - does not mention corn or grass pellets). I believe that corn is much harder on the vent pipe as opposed to wood pellets.
As for back up, how long do you want the stove to run for? You need to get a big enough UPS. Here is a link to a thread on the P61A power draw.