This ref. 902 is from Patek Philippe's early series of table clocks fitted with a 17''' mechanical movement, electrically wound and powered through the solar cells. The movement features a conventional lever escapement wound by speed increasing gears activated approx. every 5 hours by an electric micro-motor which in return is powered by an accumulator charged by the photoelectric cells on top of the clock’s case. In perfect working condition the appeal of the present clock is further enhanced by the retailer signature Gübelin,

Watchmakers are always in quest of free sources of energy, the disadvantage of light however is that it is not available around the clock. Patek Philippe opened its Electronic Division in 1948 with the goal of exploring photoelectric, electronic, and nuclear timekeeping. The department produced the groundbreaking solar clock, the first of its kind.

In 1954, Patek Philippe patented its extraordinary photoelectric energy mechanism (Patent No. 298564). Photoelectric cells charged an accumulator which then powered a motor to wind a conventional Patek Philippe 17''' hand-wound pocket watch movement. With energy stored in either the accumulator or the movement spring, the firm claimed that the clock was capable of running in complete darkness for a year and with an accuracy of within one second per day.

A similar table clock is described and illustrated in Patek Philippe Museum - Patek Philippe Watches Vol. II, p. 399, Inv. PE-16.