SFU(Space Flyer Unit), a 4-ton class experimental platform, was on orbit at the height of 480 km circular for 10 months from 1995 to 1996. It carried environment diagnostic packages which contained plasma probes and wave receivers to study the plasma environment surrounding the SFU. The potential of the SFU main body during the daytime reached about 40 V negative with respect to the ambient plasma, which was driven by the electromotive force of the SFU solar array paddles(52 V). It was found that the negative potential resulted in the formation of ion flow towards the SFU main body with fluctuations in a frequency range below 100 kHz. In the sunlight, the wave receiver detected broadband fluctuations extending beyond 1 MHz. This study provides the first observation on the plasma effects of spacecraft potential biased by the solar array voltage. ¿ 1999 American Geophysical Union