Solar is such a no brainer. Everyone has access to sunlight and can easily harness it's power.
Even in it's present ineffecient form it is worth having. If this turns out to be a viable option that makes solar even better.
I know it's not necessary but think of the advantages of being able to charge your flashlight batteries, your laptop or run a small fridge or microwave after a collapse. Perhaps run some security devices or cameras as well.