Technology opportunities to enable high mass specific power

Inverted Metamorphic Multijunction (IMM) technology has demonstrated excellent energy conversion efficiency, 32% AM0. In addition to high conversion efficiency, this technology also offers the potential for ultra-high mass specific power at the blanket level. Because the substrate is removed, the thin, flexible epitaxial cell can be incorporated in a variety of novel blanket structures. Several novel array technologies have been proposed which would take advantage of the flexible nature of the IMM by incorporating rolled stowage for launch. The flexibility of the IMM may lead one to assume that the IMM is a much higher efficiency drop-in replacement for conventional thin-film photovoltaics (ex. amorphous silicon, copper indium gallium diselenide). An important differentiation between these technologies is the radiation hardness of the different technologies to the space environment. This paper presents a study to examine the photovoltaic blanket specific mass achievable with IMM technology depending upon the orbit of interest and the end-of-life performance requirement. The impact of radiation shielding, both front and back, is assessed.