Complex sentence: It has been suggested that solar furnaces could be used in space to provide energy for manufacturing purposes, although their reliance on sunny weather means that they are unlikely to be used as a major source of renewable energy on Earth.
Split into simpler sentences: It has been suggested that solar furnaces could be used in space to provide energy for manufacturing purposes. Their reliance on sunny weather may mean that they are unlikely to be used as a major source of renewable energy on Earth.