Several electricity-consuming components for cooling and heating, illumination, ventilation, and irrigation are used to maintain proper environments of protected crop cultivation facilities. Photovoltaic system is considered as one of the most promising alternative power source for protected cultivation. Effects of environment, type of solar cell, method of installation and operation on power generation performance should be investigated for design and application of photovoltaic system suitable for specific crop, season, and location. In this study, three types of photovoltaic modules were evaluated at different installation angles and times of the day. Units used were single-crystalline, poly-crystalline, and amorphous modules. Installation angle of the modules was varied from 0° (vertical) to 90° (horizontal) on a 15° interval, and measurement times were after sunrise, noon, and before sunset. Solar radiation (total and spectrum) and generated electricity were obtained for 270 seconds for each installation angle and photovoltaic module, and optimum installation angles providing the greatest ratio of tilt to horizontal radiations. The values were 2.77 at 60° and sun-set, 2.39 at 75° and sun-rise, and 1.40 at 45° and noon, respectively, for all of the modules. Power generation was in the order of noon, sun-set, and sun-rise. Generated power of the amorphous module was about 43% of those of single- and poly-crystalline silicon modules. Results of the study would be useful for selection of installation method suitable for different crops and regions.