The Reliance group firms also sought directions to the PSUs that they should not cut power supply to them on account of non-payment of dues as it would lead to outages in major parts of Delhi.
A bench headed by Justice J Chelameswar reserved the verdict after lawyers for Delhi Electricity Regulatory Commission (DERC) and power generating PSUs concluded their arguments in the case.
Earlier, senior advocates Kapil Sibal and P Chidambaram, appearing for the BSES firms, had said the discoms were facing "unviable" financial situation and the revenue gap could only be bridged by raising the power tarrif from 20 to 25 percent.
Delhi Electricity Regulatory Commission (DERC), which fixes the power tariff, had opposed the plea of the private discoms saying they have "buffered up" the losses.
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"Tata Delhi Power Distribution Limited (TDPDL) is the third private discom which supplies power in Delhi. It also acts under the same so-called draconian regulatory regime and it has paid every penny to the power generating companies.
The BSES firms have said a major portion of the revenue was being spent in purchasing electricity from the government-owned power generating companies and the firm was denied "cost reflective tariff" from the regulator (DERC).