This is going to be my last Fool article for a while, as I'm taking a short leave to collaborate on a book about the future of energy. Until I'm back, you solar Fools will have to just talk among yourselves. (Have you visited the Renewable Energy message board? Check it out!)

First Solar (Nasdaq: FSLR) grabbed most of the headlines this week, first by snagging another large solar development pipeline, and then by reporting earnings that got investors pretty fired up.

That wasn't all that went down this week, however.

On Monday, Innovalight announced that it has hit 19% conversion efficiencies with silicon ink processed solar cells. The California company is looking to bring better than 20% efficiencies to partners like JA Solar (Nasdaq: JASO), which could really ratchet down costs. At one point, Innovalight pegged the potential cost reduction at 50%. This Harris & Harris (Nasdaq: TINY) portfolio company is one to keep an eye on.

Elsehwere on the bleeding-edge technology front, German researchers hit record 20.1% efficiencies with a thin-film cell. The cell used CIGS technology (a different sort of semiconductor from what First Solar employs), which only sports 10%-12% efficiency in commercial modules today. CIGS has had buzz for years, but the promise of the technology may be finally catching up with the hype. Companies pushing the CIGS envelope include Dow Chemical (NYSE: DOW), IBM (NYSE: IBM), and Ascent Solar (Nasdaq: ASTI).

Midweek, we heard from REC Group and Sharp, solar heavyweights from Europe and Japan, respectively. REC issued a positive outlook for the second half of the year, which is encouraging to hear from a firm that describes itself as "very dependent on the German market." (German feed-in tariff reductions have been causing a lot of analyst unease this year.) Sharp, meanwhile, says it's looking to make inroads in the utility-scale market, and will hike production by 50%, to around 1.2 gigawatts this year.

As for aspiring solar sluggers, DuPont (NYSE: DD) has taken its original $1 billion PV sales goal -- and doubled it. The company is looking for $2 billion of solar-related sales by 2014. I don't think DuPont is on many solar investors' radars yet, but this appears to be one of the more highly committed conglomerates out there.

First Solar and Harris & Harris Group are Motley Fool Rule Breakers choices. Try any of our Foolish newsletters today, free for 30 days.

Fool contributor Toby Shute doesn't have a position in any company mentioned. Check out his CAPS profile or follow his articles using Twitter or RSS. The Motley Fool has a disclosure policy.