Shanghai-based solar-wafer manufacturer ReneSola (NYSE: SOL) shares took a 20.9 percent nosedive Wednesday after the company released unaudited fourth-quarter earnings.

ReneSola shares fell $2.21 per share, closing at $8.35 per share Wednesday, then grew 3 percent to $8.60 per share in after-hours trading. It was unclear why the shares dropped, although speculated that it might have been a "buy the news" reaction, which means investors anticipated the positive earnings news in advance, leading to share prices rising 28 percent Tuesday, then settling down after the news was announced.

Fourth-quarter net income grew 87.8 percent to $17.5 million, compared with $9.3 million in the year-ago quarter, while revenues nearly tripled to $96 million from $32.3 million in the fourth quarter of 2006.

The company’s top competitor, Chinese solar-wafer manufacturer LDK Solar (NYSE: LDK), didn’t have a great day on the stock markets either.

LDK shares fell $1.47, or 6.1 percent, to $22.63 per share Wednesday after falling 7.3 percent to $24.1 per share Tuesday.

Meanwhile, private investors apparently are still interested in solar technologies that can make the most of silicon, a key ingredient for turning sunrays into electricity.

German concentrating solar company Concentrix Solar said Wednesday it has closed an undisclosed amount in a second round of financing from Good Energies, which also participated in the startup’s first round.

Spanish renewable energy giant Abengoa also contributed to the second round, which Concentrix will use to built its first industrial production line and develop markets in Southern Europe. Concentrix is teaming up with Abengoa Solar to create a joint venture — Concentrix Iberia S.A. — that will tap into the Spanish market.

Concentrix, which uses a lens to concentrate sunlight onto a smaller solar cell, already has a pilot production line.