What: Shares of renewable energy developer SunEdison Inc (NASDAQOTH:SUNEQ) dropped as much as 24% today and its main yieldco TerraForm Power Inc (NASDAQ:TERP) also dropped 18% after they released earnings results.

So what: Third-quarter revenue increased just 1.5% to $476 million and net loss grew slightly to $284 million, or $0.91 per share. That far exceeded Wall Street's estimate of a $0.65 loss per share and shows a slow turnaround in selling projects for a profit as SunEdison hopes to start doing more.  

TerraForm Power said it generated $71 million in cash available for distribution in the quarter and raised its dividend to $0.35 per share. On an annualized basis that gives the stock a 9% dividend yield, but not even that could save shares today.

Now what: One of the big problems is that debt has ballooned from $6.99 billion a year ago to $11.67 billion at the end of the third quarter, including $7.88 billion in SunEdison's level (the rest is in subsidiaries). But with losses continuing, revenue stagnant, and the yieldco's dividend yield so high it won't be able to buy projects, investors don't know what SunEdison is going to do.

I've called SunEdison's business a house of cards in the past, and that's true today more than ever. Management thinks it can get to cash flow positive by the middle of next year as it focuses on higher-margin projects, but whom is it going to sell those projects to?

I have my doubts about SunEdison's long-term plan to make money and think it got too far over its skis building out a renewable energy giant. Until it can prove the ability to build projects and sell them profitability, and reduce debt, this isn't a stock I would be buying.