  Photovoltaic (PV) modules have been employed in visible light communication
(VLC) for simultaneous energy harvesting and data reception. A PV-based
receiver features easy optical alignment and self-powered operation. It is
commonly assumed that PV modules in VLC have a linear optical-electrical
response, which is generally true under high illumination levels. This paper
will illustrate the exacerbated PV's nonlinear distortion when under typical
indoor illumination. The nonlinearity of a PV module for different numbers of
PV cells is also characterized. We investigated the transmission performance of
a 1-Mbit/s PAM4 signal under different illuminance. Experimental results show
that the bit-error rate (BER) first decreases and then increases with the
increasing illuminance. Thus, an optimal illuminance to minimize BER exists. In
addition, we demonstrated two distortion mitigation methods, namely localized
distortion compensation lighting and post-distortion compensation. BER
reduction from 3.2x10-1 to 2.6x10-3 and 2.8x10-2 to 1.5x10-2 are achieved with
the two respective schemes.
