Prepare in advance.
The electricity in the Punta Cana tourist zone is 24/7 with little interruption. However, this does not excuse one from taking measures to have a backup source of power should there be an extended interruption caused by a major equipment fault or natural disaster. Got to say when Hurricane Jeanne passed over the area in Sept 16, 2004 PJT lost public power from about 4:00 am to 8:00 pm. Yet, he had a generator that was put to used during the outage. The question you have to ask yourself is can you or want to get by without power for a short period or should prepare to have backup power source for an extended period. It's not like you can take a trip to Home Depot or Lowes should things go awry, you have to prepare in advance as it will be your only opportunity.
Regards,
PJT