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 upgrades and downgrades -- just in case their reasoning behind the call makes sense.

What: Shares of solar products company ReneSola (NYSE:SOL) climbed 4% in pre-market trading Tuesday after strong quarterly results prompted a upgrade from neutral to buy from Roth Capital.

So what: Along with the upgrade, analyst Philip Shen boosted his price target to $5 (from $3.80), representing about 30% worth of upside to yesterday's close. So while momentum traders might be turned off by the stock's sluggishness over the past several months, Shen's call could reflect a growing sense on Wall Street that ReneSola's prospects are now too cheap to pass up.

Now what: According to Roth, ReneSola's risk/reward trade-off is quite attractive at this point. "We believe the integration into poly differentiates SOL by allowing the company to preserve (and potentially even expand) GMs in an environment where spot poly pricing increases to $25/kg, which we now view as a realistic scenario," said Shen. "Additionally, we like SOL's differentiated OEM approach to capacity expansion as it requires less capex vs. in-house expansion and allows for a more nimble manufacturing approach given the fluctuating state of global tariffs." Of course, given ReneSola's still highly volatile and speculative nature, only the most risk-tolerant of investors should consider buying into that bullishness. 

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.