I am trying to understand the roles of the QPU and the solvers in a quantum device, specifically I am reading for this purpose the documentation of D-Wave. While it is clear to me that the QPU of a quantum device could be defined as the quantum chip that contains interconnected qubits, a solver, as far as I understood, is a resource (not a physical one) responsible for the encoding problem, a sort of intermediary between the quantum device and the optimization problem. (Please, correct me if I am wrong)
Could the QPU be treated as a solver in some cases?
Thanks in advance.