Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of residential solar installer SolarCity (NASDAQ:SCTY.DL) jumped as much as 18% today after announcing an acquisition.

So what: SolarCity is buying solar module start-up Silevo for $200 million with another $150 million potential in earn-outs. This is the company's first move into solar panel manufacturing and further vertically integrates the company. 

Now what: On a conference call today, Chairman Elon Musk said that he was worried the world wouldn't have enough solar panels for SolarCity when it increased installations to near 10 gigawatts per year. He also said that conventional panels aren't efficient enough and Silevo's higher efficiency should help lower costs on a per kW-hr basis. This is a massive bet on a technology that's not yet proven at the scale SolarCity is talking about, so it's a huge risk but a big opportunity at the same time.