First Solar is buying an under-the-radar startup called TetraSun to add expertise around silicon solar cell manufacturing to its technology portfolio, which until now has focused on using the material cadmium telluride to make solar cells.

The Arizona-based thin film solar giant announced the pending acquisition on Tuesday during its analyst day — its first since 2009 — in which it laid out a persuasive technology and business development plan for the next five years. Investors liked what they heard and pushed the company’s stock up by nearly 50 percent during trading.

So why TetraSun? Apparently Silicon Valley-based TetraSun has some disruptive silicon cell designs that set it apart from the rest of the silicon solar companies. Its designs require fewer manufacturing steps to produce conventional silicon cells, and eliminates the need for silver and transparent conductive oxide. Silver is used to transport electricity produced by the cells, while the oxide is a coating that protects the cells and helps the semiconductor material (such as silicon or cadmium telluride) to grab the light more effectively to produce electricity.

First Solar claims that TetraSun’s cells also can perform better in hot climates than conventional silicon cells. That feature will make solar panels with TetraSun’s cells more desirable in places like the Middle East and India, two markets with a lot of potentials for growth. First Solar says it plans to start making TetraSun’s cells in the second half of 2014.