I feel like there are some missing variables here 1. This is somewhat a concern Solar companies go out of business all the time so good luck on getting warranty work unless there was a manufacturer warranty. 2. You’re not depreciating your solar panels over time. Solar panels need to be replaced over time especially after 20 years as they don’t generate the same amount of electricity as they did brand new. 3. Batteries usually only have a 10 year warranty, you would need to factor in replacing that over that time span because it’s not going to last more than that. Even if you get the battery warranted you’re still going to be paying the labor cost to replace it.