This article refutes the assertion, based on an examination of the photoelectric effect, that Planck's
constant is universal, as well as the quantum mechanics that underlies it. Several errors in the energy
balance equation for the photoelectric effect are revealed. It is shown that the quantum yield influences
Planck's constant. The need to account for the efficiency of photovoltaic energy converters (PVCs) and
their relationship to quantum yield is substantiated. The true meaning of a radiation quantum as the
energy required to maintain the "idle" state of a PVC is established, along with its dependence on the
type of photocathode and its operating mode. Based on this, a classical explanation is given for the laws
of the photoelectric effect discovered by A. Stoletov, and the conclusion is drawn that it is erroneous to
contrast it with the laws of quantum mechanics.
