“My dad claims that it never paid for itself but I skeptical. All of their hot water needs were covered “
NO, NO, NO. That is not passive solar. That is solar hot water. It is expensive. It is theoretically possible to make a completely passive solar hot water set up, but it is seldom done because the heat exchange is so poor.
There are do it yourself ways to do solar hot water which can be more cost effective, but they tend to be “red-neck” :-) or less professional.
Non passive = photovoltaic cells to generate electricity.
Passive (everything else) = uses the heat energy and the heat transfer process to do “passive” things like heat water, heat the house in winter, etc. It can be as expensive as a solar cell heat exchange system or a barrel of water painted black.