Tumbling solar-plus-storage costs could see the hybrid technology become a money saver for US firms grappling with expensive legacy coal portfolios, according to the Institute for Energy Economics and Financial Analysis (IEEFA).

Utilities shutting down coal units ahead of their end-of-life point and replacing them with renewables, stand to reap savings in the “hundreds of millions”, the think tank claimed in a recent update.

PacifiCorp, a subsidiary of Warren Buffett’s Berkshire Hathaway Energy, is one a raft of utilities IEEFA said is “reckoning with a new reality” of coal closures. In a recent review, the firm found early retirement of certain coal units would create “potential benefits” for its 1.8 million customers.

According to IEEFA, PacifiCorp’s coal units can’t compete with “cheaper and cleaner alternatives” despite their high power performance levels. For the firm – reportedly the largest grid operator in the US West – the savings from early closures could reach the US$248 million mark, depending on scenarios.