If you’ve invested in solar stocks this year, you’ve likely got a big, sunny smile on your face.

Stocks in the sector have been on fire, with many of the group’s stalwarts logging triple-digit percentage gains in just the last six months. As a group, solar stocks have been bid way up this year, and that has sent the Guggenheim Solar ETF (TAN) — which holds a basket of the solar standouts — up more than 50% year-to-date and more than 75% during the past six months.

And while those gains are stellar, they pale in comparison to the gains in some of the fund’s top holdings.

Take First Solar (FSLR), which is the biggest single holding in TAN. This industry leader’s shares are up nearly 100% during the past six months.

Then there’s MEMC Electronic Materials (WFR), which is up more than 165% during the past six months.

Finally, there’s the big winner in the group, SunPower (SPWR). This stock has exploded, with an incredible 330% flare-up in the past half-year.

So, with all of the extreme gains we’ve seen in the sector, you would think that now would be the time to start considering lightening up on your positions. And certainly, if you haven’t stepped into the sun yet, now doesn’t seem like the time to do so.

But don’t tell that to Goldman Sachs.

On Thursday, Goldman solar analyst Brian Lee sent out a note to clients that was very bullish on the sector. He cited factors such as a clear picture for strong earnings growth in the near term as reasons for the optimism. More importantly, Lee upgraded his 12-month outlook on solar, raising the price targets on the aforementioned First Solar, MEMC and SunPower.

Lee upgraded FSLR to “buy” from “neutral” and raised his price target on shares to $64. He also called WFR Goldman’s top idea in the space, improving his rating to “Conviction List buy” from an ordinary “buy” and raising his price target to $10. And there was some love for SPWR in the note, as Lee upgraded shares to “neutral” from “sell” and set an $18 price target.

Now, I like Brian Lee, and I think he’s a good analyst. However, it certainly seems like Goldman is late to the party on this one.

Then again, analysts arriving late to the party is nothing new. When I was a broker at Morgan Stanley, we used to laugh at this kind of late-to-the-party call by joking that our research department had just declared that bees were now bullish on honey.

Still, despite the Johnny-come-lately status of the Goldman call, I do agree that solar stocks are likely to continue shining due to the potential for strong earnings growth driven by increasingly positive demand metrics. Strong demand for solar in places such as China, Japan and even the United States is likely to keep revenue and earnings shining, and that’s likely to keep a bid in on solar stocks.

Will the solar party keep raging the same way it has over the past six months? I suspect not, but that doesn’t mean there isn’t still a little sunshine left for investors to bask in.

As of this writing, Jim Woods did not hold a position in any of the aforementioned securities.