Batteries don't last forever. Sometimes can be easily recycled, those materials used to make new batteries. If anyone knows what equipment is needed to do this, and the cost of setting up a small scale community system, please add that information here.
Solar cells loose efficiency over time but if well made will last forever. Watch out for low quality ones from China that break within the first year. Search for reviews from those who have purchased from that company previously before buying the product.
Gasoline goes bad after one to two years. If you want to stockpile fuel, get 100% alcohol. You can also make alcohol easily from a bag of sugar.
Medications go bad after a time. Best to grow the plants and produce what you can on your own if possible.
Birth control will run out. You don't want people to have more children than they can take care of, or want. And most women probably don't want to remain pregnant all the time anyway.
Do you have a doctor in your group? What about a dentist? How are you prepared to deal with various problems that may emerge?
You can make your own electricity by taking the alternator from a car, and building a windmill blades from some boards or other material, and producing a junk metal windmill that way. If doomsday comes to us, there should be plenty of dead vehicles around to salvage from. If a storm damages it, its easy to repair or replace.