NASA is incorrect when it says the radiation output of the sun is changed very little over the course of the sunspot cycle. Their own studies prove that wrong, but they still cling to that statement like a drowning man in a sea of lies. UV light is radiation. So the radiation output and energy output of the sun varies significantly and dramatically during the solar cycle. However visible radiation varies little just due to the inherent nature of the sunspot area. Dark areas form next to bright areas. NASA has been wrong about this for decades.
“However, there are more important indirect effects: sunspots are associated with what we call “active regions”, with large magnetic structures containing very hot material (being held in place by the magnetism). This causes more ultraviolet (or UV) radiation (the rays that give you a suntan or sunburn), and extreme ultraviolet radiation (EUV). These types of radiation have an impact on the chemistry of the upper atmosphere (e.g. producing ozone). Since some of these products act as greenhouse gases, the number of sunspots (through association with active regions) may influence the climate in this way.”
http://sohowww.nascom.nasa.gov/classroom/notsofaq.html#SUNSPOT_CLIMATE