On a satellite in low-Earth orbit, solar energy incident on the solar cells provides a power of 1,400 watts per square metre.
Certain interplanetary probes operating in deep space a very long way from the Sun have solar panels spanning 30 square metres and use nuclear radioisotope thermoelectric generators (RTGs) as a supplementary power source.
Most energy consumed is converted to heat, which does not dissipate easily. Heat exchanges therefore have to be controlled to avert overheating or excessive cooling.
The satellite’s internal temperature is regulated by reflective and insulating blankets. Excess heat is rejected to space by radiators.