What is Cross Subsidy Surcharge?

Cross Subsidy Surcharge (CSS) is a penalty imposed to HT consumer where they are purchase power through private sources when TNEB is having surplus power.
The advantage of sourcing power through Renewable Energy is that the CSS is charged only for 60% as a need to promote Green /Renewable Energy. This benefit is not implied for Thermal Power plants.
The consumer still gets a decent saving in the energy cost irrespective of CSS imposed.