It's worth modeling the cost of capital of your system to provide a fair comparison. Assuming the it lasts 20 years before you need to replace it entirely and a

It's worth modeling the cost of capital of your system to provide a fair comparison. Assuming the it lasts 20 years before you need to replace it entirely and after maintenance you save $2600 a year ($217/month) then what rate of interest could you pay if you took out a loan to cover the initial capital outlay? Plugging the figures into: https://smartasset.com/personal-loans/personal-loan-calculator https://smartasset.com/personal-loans/personal-loan-calculat... and adjusting the interest rate slider you get a monthly payment of $217 when the interest rate is 11.75%. That's a pretty good rate of return for your investment. Not ridiculous, but solid.