The northwest area provides ideal situation for installing PV power systems with its rich solar resource and open area

such as Gobi desert. A prototype of a shaded photovoltaic module is presented. And then

the typical shading types are concluded

which is classified as front row shading

vegetation

wire poles and distribution rooms and birds dropping after longtime surveys and observation. The shading effects caused by some particular obstacles are measured and analyzed according to the field test on a 20-MW PV system. Reduction of the I-V and P-V characteristic has been observed and compared with the theoretical value.In the end

some suggestions on dealing with these shading problems in the installation and operation of the PV system are proposed.