Tata blamed the slow progress on the delay in getting permission from the local authorities for laying the network.
It also blamed the regulator for not approving the proposed investment for the work.
Commission member Chandra Iyengar pulled up Tata Power for disobeying MERC directives Consumer representative Ashok Pendse too was highly critical of the company.
Other representatives Rakshpal Abrol and Sandeep Ohri justified the delay in laying the network.
In its statement, Tata said that it has added around 8,000 to 9,000 consumers every month since August.
The MERC directed Tata to file a statement based on Reliance Infra’s submission by July 19 and give details of the network rollout since 1998.
It has also asked Reliance to file their reply on Tata submissions by July 24.