During the 1960s, Patek Philippe explored an unusually inventive approach to table clocks with its Pendulettes à remontage automatique par la lumière; clocks whose mechanical movements were automatically wound using energy derived from light. Rather than using solar energy simply to power a conventional quartz movement, photovoltaic cells generated the energy required to wind a traditional mechanical calibre. The resulting clocks brought together emerging technology with the traditional mechanical watchmaking for which Patek Philippe was already renowned.

Introduced around 1964 and produced for approximately five years, the ref. 503 is among the rarer expressions of this concept. Its architectural gilt-brass cabinet houses the calibre 17-250 E, derived from a pocket-watch movement and mounted horizontally within the case. Beyond its unusual solar winding system, the reference incorporates a perpetual calendar, making it considerably more complicated than a conventional Patek Philippe desk clock. With only a small number of examples known, the ref. 503 represents a fascinating and distinctly experimental chapter in the manufacture's mid-century history.