Plus the time getting the material, driving to the hardware store another time to get something you forgot, doing the registration, plus the time needed for planning/ calculation of economical feasibility/ decision making. Even at a very moderate 50 € per hour rate (for the typical Gamer) the material cost is the smallest part of the project. Treat it as a hobby, but don’t tell me it is an investment.

You get everything you need shipped from Amazon. You open the box and install it. These things are designed to be set up by amateurs. It’s half a dozen screws per panel. To hardest part is lifting the panels outside the balcony.

As with many things, the hardware store is probably going to be rather expensive and transport is a hassle (most people do not have a car with enough space to transport solar panels). So you order this stuff from specialized companies who will deliver it to your doorstep in one more or less convenient shipment. Same for pretty much any bigger, more expensive things needed when building or extending a house. Hardware stores are convenient if you quickly need something but that's mostly it, IMO.