This all depends on what you want to achieve and what space you have available. Do you want to save on your monthly electricity bill? Do you want to go completely off the grid? Or do you simply require backup power for those dark times?
Solar can be a tricky affair, as we mentioned in our answer about solar panel suitability, we detailed that solar is a lifestyle change, and may not be a solution to every situation.
Solar installations can also be limited by available roof or mounting space, and shading from trees, buildings, etc. can ultimately influence where panels can be installed.
Please refer to our answer on solar installation types for more information.