The Space Solar Sheet of two configuration types using InGaP/GaAs/InGaAs triple junction solar cells has been developed. Two types of shielding material are utilized for the Space Solar Sheet. One type uses transparent resin films (Film type), and the other one uses cover-glass and back-sheet (Glass type). This solar sheet has possibility of the realization of the lightweight and high efficiency solar panel. Detailed reliability tests of the two types of solar sheet were performed to confirm their tolerance in a space environment. The test results indicate that they have high reliability in a space environment. Depending on the space environment and the application, two types of solar sheets can be properly used.