Development of engineering of solar space power system involves as a first stage the launch of demonstration space solar power plant (SSPP) based on the current satellite platforms and launch vehicles. The type of general-arrangement diagram of space segment of SSPP will be the class of transformable structure of photo convertors with maximum surface area. In this manuscript is carrying out analysis of different versions of transformable structures of photo convertors in PROTON launch vehicle use. It is proved that such kind of version would allow successfully implement demonstration SSPP with reasonable power of transferable laser energy to the ground receiving point.