While Fools should generally take the opinion of Wall Street with a grain of salt, it's not a bad idea to take a closer look at particularly stock-shaking analyst upgrades and downgrades -- just in case their reasoning behind the call makes sense.

What: Shares of SunEdison (NASDAQOTH:SUNEQ) jumped more than 11% Monday following an analyst upgrade.

So what: Citing valuation upside potential from the successful execution of  the renewable-energy specialist's yieldco strategy, Deutsche Bank analyst Vishal Shah upgraded shares of SunEdison from hold to buy. Shah simultaneously increased his per-share price target for SunEdison from $13 to $35, representing a more than 60% premium for investors even after today's pop. Shah also expects "the emergence of 5-6 publicly traded yieldcos over the next 12-18 months to act as a robust growth enabler" for the solar sector as a whole.

Now what: SunEdison shares rose just over two weeks ago after the company announced the proposed initial public offering of its indirect yieldco subsidiary, TerraForm Power. As a yieldco, TerraForm generates revenue from long-term power purchase agreements with utility companies, and gives businesses like SunEdison a place to sell their solar installations.

SunEdison isn't profitable on a trailing 12-month basis, and shares don't exactly look cheap trading around 166 times next year's expected earnings. But that's also not uncommon for a company on the cusp of achieving sustained profitability. If SunEdison continues moving in the right direction, as expected, I see no reason the stock can't also continue rewarding patient long-term investors.