Shares of thin film solar maker First Solar (NASDAQ: FSLR) rocketed up more than 20% this morning on a great earnings report and analyst praise.

While it technically announced its earnings yesterday, the impact of its numbers apparently only sank in overnight.

First Solar reported extremely strong Q4 results with revenue of $52.7M and non-GAAP EPS of $0.16, beating most analysts' estimates. Year-over-year growth in revenue was an impressive 388%, with gross margins topping 50% and operating margins topping 24%, excluding stock based compensation charges.

"We continue to be very excited about the company and firmly believe it is a 'must own' in the solar space," wrote analyst Dave Edwards of ThinkEquity to clients.

First Solar modules are based on a Cadmium telluride (CdTe) thin film process, and are designed for large scale, grid-connected solar power plants. They're also sold to leading solar project developers for use in commercial photovoltaic (PV) projects. While they're not as efficient as silicon-based PV panels, they're less expensive to produce.

The company appears to be doing a good job boosting production while controlling its costs.

"First Solar has two powerful levers to pull to improve its operating efficiency: power per square meter and square meters per minute. It is clear by the company's performance this quarter that the company successfully pulled these levers in Q4. The result was a substantial increase in throughput and a reduction in manufacturing costs per watt of 12% from the prior quarter to $1.25 per watt," wrote Edwards.

Demand for its products does not appear in short supply. Today First Solar announced it will supply solar modules for a 40-megawatt solar power plant to be constructed in the Saxon region of Germany in the municipality of Brandis.

Upon completion, the €130 million project will be one of the largest photovoltaic projects in the world, utilizing approximately 550,000 solar modules and producing around 40 million kilowatt hours of clean power annually. Construction is scheduled to begin in the second quarter of 2007 and is expected to be completed within 30 months.

A new factory First Solar is building in Germany to augment its Ohio production site is expected to be online later in 2007, and the company has also announced plans to open a facility in Malaysia in 2008.

First Solar expects to have $310 million to $340 million in sales this year, but profitability will depend on start-up costs in Germany, the company warned.

In morning trading today, shares of First Solar were up $7.14 to $41.42, almost 21%.

First Solar went public in November of last year. See Cleantech.com's First Solar still edging up.