You can nitpick all you want, as the market appears to be doing, but compared to almost any company, GT Solar (Nasdaq: SOLR) reported outstanding earnings last night. The equipment maker's mix change may leave some lumpy results in the future, but it looks like smooth sailing for now.

In the fiscal first quarter, revenue grew 71% over last year to $231 million, gross margin improved to 49%, and to top it off, earnings per share grew 273% to $0.41. Maybe most impressive is the company's $2.3 billion backlog, which includes $952.5 million from the sapphire business that had very little revenue this quarter.

If you wanted to focus on one negative, that would be a slowing of the photovoltaic and polysilicon business. They're both maintaining demand at near historic levels for now, but the question is, will that demand fall off as customers like LDK Solar (NYSE: LDK) and Trina Solar (NYSE: TSL) slow expansion?

Even if the photovoltaic and polysilicon businesses fall off next year as some analysts predict, GT Solar's growing diversification will weather the storm.

Cheaper by the day
One of the reasons I called GT Solar one of the best cleantech stocks in both June and July was its incredibly low valuation. Based on the company's reiterated guidance of $1.55 to $1.85 in earnings per share for fiscal 2012, shares are trading between a 6.8 and 8.1 forward earnings multiple. Seriously?

Combine that with the fact that GT Solar has a $1.6 billion market cap, $473 million in cash, and just $95.6 million in long-term debt. Even if solar demand slows in 2012, GT Solar has an up-and-coming sapphire business and a ton of cash to weather the storm. It seems like a very cheap stock to this Fool.

It's all in a name
GT Solar also announced it was tired of being associated only with the solar sector and will now be known as GT Advanced Technologies. The company's ticker will also be changed to GTAT on Monday, August 8, so make sure to make the change in you newsfeeds and on My Watchlist.