David Tepper is pissed of about TerraForm Power

David Tepper, founder of the hedge fund Appaloosa Management, has stepped up his public battle with TerraForm Power, a company that owns and manages solar-energy projects.

Appaloosa, which owns 9.5% of TerraForm, sent the company a letter demanding to see all documents related to a deal announced in July in which TerraForm Power's parent company, SunEdison, attempted to purchase Vivint, the second-largest installer of residential solar panels in the US.

Appaloosa wants to see books, minutes, analysis, transaction documents, engagement letters, retention agreements — everything.

The fact that Appaloosa is waging a public battle is really odd. The hedge fund is typically very private.

SunEdison, which makes solar-power devices, financed the deal with debt and by selling $922 million of assets to TerraForm Power.

The market hated the deal, seeing it as a sign that SunEdison was cash-poor. The deal sparked an epic dive in SunEdison's stock, which is down 73% year-to-date.

In Tepper's view, SunEdison sold TerraForm Power crappy assets, which is unfair to shareholders. His fund sent TerraForm Power a letter about this at the end of November. TerraForm Power announced this month that it would improve the deal.

But the improvements are clearly not enough for Tepper and Appaloosa, with SunEdison still locking TerraForm Power into a take-or-pay agreement in which TerraForm has to buy residential solar assets from SunEdison or pay SunEdison a fee.

TerraForm Power's stock is down 1.7% on this news. SunEdison's stock is getting hammered, down 25%.

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