If only people would understand, most reputable manufacturers offer a 25year production warranty.
I feel, as the standard size Solar array most retailers & installers offer is 6kW solar, this is largely due the the Fact that they get the system owner to sign over there STC to them. That is largely due to a 6kw system providing some $3’600 in STC to Install 20+/- panels odd, onto what is simple roof racking, not bad for what should commonly be a days work!
With the current low cost of Solar panels, NiFe and newer safer LiFePo4 Battery technology cost 550kW, most systems Owners these days would be a lot smarter/better-off investing in a Battery bank, that simply stores the energy usage from sunset through to sunrise, where Solar takes over again.
What that means: A Solar system only needs to provide slightly more kWh energy than a customers largest 24hour consumption, as once the batteries are charged, thay will provide the energy through to the next sunrise, instead of paying (if grid connected) three times the cost of any feed-in-tariff (FIT) rebate the retailers offer during the day!
However, I doubt may retailers guide customers in that direction, as the STC on a 6kW are to tempting to resist, especially where possibly half the panels may only be required.
In my opinion, with battery storage also being so affordable, that is taking advantage out of ill informed !