A well-designed and maintained PV system will operate for more than 20 years. The PV module, with no moving parts, has an expected lifetime exceeding 30 years.  Standard warranties for solar panels are 20-25 years depending on manufacturer and 10 years for inverters.  From experience, solar PV system issues are not very common but if system problems occur, they will most likely be the result of poor installation or design.  Failed connections, insufficient wire size, components not rated for dc application, etc are failures due to poor design or installation.  

The more un-common cause of problems are the failure of electronic parts such as the controller, inverter, or protection components. Batteries will fail quickly if they are used outside their operating specification. In most applications, batteries are fully recharged shortly after use. In many PV systems the batteries are discharged and recharged slowly, maybe over a period of days or weeks. Some batteries will fail quickly under these conditions. Be sure the batteries specified for your system are appropriate for the application.