The average solar system will last 15 to 20 years (double that of gas, with servicing running from nil to heavy, depending on the type of design. A Heliocol solar system will last beyond 30 years.In my case, I've saved $40000 in fuel ($2000 a year to heat my 18' x 40' inground pool), and roughly $9000 or $10000 in replacement heaters which last only 8 to 10 years. I've saved almost $50000 over 20 years, and expect to save another $23000 over the next 10 years.
A Heliocol solar system will cost between $3000 to $5000, and $300 for maintenance over the next 30 years! Over the lifetime of a Heliocol solar system, you are likely to purchase from 2 to 6 new cars! Go for value, rather than price at all costs.