Hydroponics can be as simple or complex as you choose. It's entirely possible to grow crops without electricity, but you're likely to get more abundant crops with a little bit of added complexity. Without using electric pumps, you'll probably need to set your system up to manage water flow using gravity, which means you'll need to manually transport water back up to the starting tank with your own muscle power at the end of each day. Alternatively, you can use a simple wicking system to draw water from a stationary tank into the root zone.
Without electricity, you won't be able to provide artificial light, so you'll need to plan your hydroponics setup accordingly and you may have to restrict use to summer growing season when natural light is at its maximum.
