Crossbench deal-maker Nick Xenophon has defended helping the Turnbull government land its company tax cuts, saying his negotiated terms will improve power supply security, and help low-income earners pay their power bills.

Under attack from Labor and the Greens for the agreement secured on the sidelines of Parliament on Friday, Senator Xenophon said welfare recipients would get help with their winter power bills, while Australia's energy market would also be more effective.

The deal secured one-off payments to low income households worth $260 million and plans for a "power affordability and reliability policy", the details of which are yet to be announced. The government agreed to consider policies to bring unused gas fields on line and to encourage more domestic gas supply.

"I did the best I could in the constrained set of circumstances... to put downward pressure on power prices and to comply with our Paris Agreement targets," he told ABC radio on Monday.