Why have solar thermoelectric generators not competed well with silicon solar cells in spacecraft?

The premise that solar thermoelectric generators have not competed well with silicon solar cells in spacecraft is accurate. While solar thermoelectric generators have been designed for use in orbiting spacecraft, they have struggled to compete with silicon solar cells primarily due to two factors: lower efficiency and higher unit weight.1

In contrast, silicon solar cells offer superior performance in these critical areas, making them the preferred choice for most spacecraft designed for extended periods in Earth orbit. While thermoelectric technology remains vital for space exploration, it is most commonly utilized in the form of radioisotope thermoelectric generators, which provide a reliable, long-lived power source for deep-space probes by converting heat from radioactive decay directly into electricity.213