Hi Mae

There are some great threads on this topic in the
Policies and Procedures forum that you might find helpful. When you click through to that forum, use the 'Search this forum' option on the inside right hand corner there to search for 'vacation' and they'll turn up for you.
Personally, I haven't had to deal with an extended lack of electricity but the few times I was abroad or traveling and the power or internet went down I would go to and use a local coffee shop's wifi or similar to check email, notify clients (if necessary), and get some work done.
The nice thing about working for yourself is that you set your own schedule and don't necessarily have set business hours (as long as the work gets done and deadlines are respected, clients don't really need to know when or from where you are working) so these kinds of issues can be circumvented for the most part.
And I've (thankfully) never been so sick that I couldn't prop myself up on the couch with my laptop and get things done.
With that said, I do know that some VAs who live in areas that are plagued by hurricanes etc. do have clauses in their contracts relative to this kind of thing and I think some of those situations are mentioned in the threads you'll find in that other section.
I also know that some VAs will create a network of 'backup VAs' who are trusted and known to them that they can call on in the event of an emergency. Other VAs run larger teams and can parse out work to someone on their team as needed.
I hope this helps a bit!
Surely you'll receive more answers on this thread from those who've had more pressing experience with the situations you're looking at.