It is not uncommon for a Solar Panel Seller or Manufacturer to offer a long term warranty on their products. These warranties generally cover the actual panel and additional components such as the Solar Inverter and the Solar Tracker.
Most of the time it is up to the company making the promise to fulfill the obligation in the future. One big challenge is that the buyer of the products are relying on the seller or OEM to be in business in the future to pay any claims.
Some buyers require the seller to obtain backing for their warranties to ensure performance in the future, regardless of the status of the seller. In addition, some buyers want a longer warranty than the seller offers.
Solutions exist to provide buyers and sellers with secure backing for their Solar Panels and other ancillary components. These are generally custom solutions based on each unique situation.