Why would I get solar instead of instantaneous water heaters?

Instantaneous water heaters only replace about 15-25% of the energy used by a conventional water heater while solar water systems replace 70-90%. An article by Consumer Reports states that the tankless heater "savings can add up to some $50 per year compared with conventional heaters. But even at that rate, it will take more than 25 years for an average household to recoup the extra $1,300 or so those units cost to buy, install, and maintain." An average family can expect $300-500 savings each year.