In comments to the Texas PUC in a rulemaking proceeding concerning substations, NRG Texas Power LLC and various other NRG companies said that increased transmission costs are an, "alarming trend," and said that the PUC, "should consider actions that would mitigate the continued escalation in TCOS increases for the benefit of ERCOT consumers."

NRG said in its comments that from 2002 to 2018 ERCOT annual TCOS have increased by $2.2 billion or 298%.

NRG said in its comments that, "Some of the increase in TCOS is attributable to the development of Competitive Renewable Energy Zones (CREZ). However, since the completion of CREZ in 2014 the ERCOT transmission rate base has grown by billions per year while annual TCOS collections have grown by several hundred million per year to now total more than $3.5 billion. Drivers of the post-CREZ transmission cost increases in the ERCOT region include a variety of projects for reliability, economic projects that support wind development and other projects needed for system maintenance and new generation interconnections. In 2018 $2.8 billion of new transmission infrastructure has either been energized or planned and will soon become part of the annual transmission cost charged to loads. More than $5 billion of transmission development is in the engineering, routing and construction pipeline for the six-year period of 2019 - 2024. Moreover, these cost figures do not include all of the transmission projects that exceed $50 million that are currently undergoing ERCOT Regional Planning Group (RPG) review and approval."

NRG's comments can be found here