NEW YORK ( TheStreet) -- Pre-announcement season picked up steam in the solar sector on Tuesday, with two solar inverter companies and one polysilicon company saying they wouldn't meet previous earnings guidance.

While many solar stocks have fallen to levels that some solar experts consider "trough" values, the risk of guidance revisions and a weak third-quarter outlook remains an overhang on the sector, coupled with a lack of positive catalysts for shares.

The most significant pre-announcement came from U.S. solar inverter company SatCon ( SATC). SatCon didn't only lower its second-quarter revenue guidance to a range of $45 million to $47 million (down from $50 million to $60 million), but showed significant balance sheet vulnerability, slashing its work force by 15% and issuing $16 million in convertible debt to an institutional investor.

SatCon's peer inverter company Advanced Energy Industries ( AEIS) also revised its second-quarter revenue guidance to a range of $137 million to $140 million, below the range of $148 million to $160 million previously provided by the company. AEIS said that earnings would be at the low end of or slightly lower than the previous guidance of 36 cents to 44 cents a share.

SatCon shares declined by 23% on heavy volume on Tuesday, while AEIS shares declined by 12.4%.

Power-One ( PWER), the largest of the three U.S.-based solar inverter companies, was down 6.7% on the news from its peers, though it hasn't revised its guidance of revenue of $250 million to $270 million.

The SatCon and Advanced Energy Industries revisions are relevant to Power-One in several respects. First, while SatCon and AEIS are more focused on the U.S. solar market than Europe, where Power-One is a dominant player, European market weakness was cited in the guidance revisions. Second, Power-One has been focusing on its U.S. sales effort as a buffer against declines in the European market. The solar inverter company revisions suggest that the second-quarter conditions in the U.S. were less robust than expected. Finally, the solar inverter market has been working through an inventory glut in the first half of the year, and SatCon cited this glut in projecting an earnings miss.

Solar inverter companies often make the argument that they are insulated from the pricing pressure that exists at other points in the solar supply chain. Power-One also notes that its pricing has been lower than competitors to begin with, alleviating the need to slash pricing. However, when an entire market is not buying solar modules because it expects further price declines, and financing and permitting delays continue, it has a larger impact on the inverter market than any relative pricing strength.

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