Fox flasher MkII – high power 2 LED solar powered beacon described a LED driver for an animal deterrent using a Chinese 8051 architecture microcontroller, the STC15F104E.
This article documents its failure in June 2018 after three years service.
With the passage of time, the PV array surface has degraded until solar collection was insufficient to maintain the battery over several heavily overcast Winter days.
Above, a close up of the PV array surface. The pic is of about 8mm width, and one can barely see the silicon stripes which are about 2mm wide.
Two problems were identified:
- the UV activated adhesive securing the clear cap over the LDR had degraded and although still in place, it was pushed off with little effort; and
- the surface of the PV array was crazed and maximum current on full sun had degraded from 160mA to 17mA.
The issue of the PV array is a serious one. It is low cost and comes from China, but there appears to be no way to buy produce with a known quality that includes UV resistance resin used to encapsulate the cells. It is a significant problem to solve.
Meanwhile, it was repaired like for like to buy time to evaluate other options. A new PV array from the same batch as the first was installed, and a new cap glued on with the same adhesive, battery charged and the thing reinstalled in the garden.