It's not the best day to be a publicsolarinstaller.

Broomfield, Colo.-based Real Goods Solar (NSDQ: RSOL) discovered that during its Nasdaq debut Thursday (see this Green Light post). The residential installer’s initial public offering began at $10 per share – at the low end of the expected $10- to $12-per-share price range – and shares fell 12 percent to close at $8.80 per share.

In after hours trading, the stock fell another 1.7 percent to $8.65 per share.

The same day, Akeena Solar (NSDQ: AKNS), a large solar installer in Los Gatos, Calif., fell a whopping 19.4 percent to $5.35 per share after missing first-quarter expectations and lowering its full-year guidance (also see this MFFAIS post).

The company posted a net loss of $4.6 million, or 16 cents per share, which represents a loss that nearly quintupled the $933,000, or 6 cents per share, loss of the year-ago quarter. Analysts expected a loss of 13 cents a share, excluding one-time items, according to Reuters Estimates.

The loss came in spite of net sales that grew 94.7 percent to $12.2 million, compared to $6.3 million in the first quarter of last year, which met analyst expectations. Operating expenses nearly tripled to $7.1 million from $2.4 million due to more offices and employees, the company said.

Akeena said it will cut staff and streamline its operations. It also lowered its guidance for the full year, forecasting growth of 40 to 50 percent over last year’s revenue of $32.2 million, down from a March prediction that it would double revenue this year.

The reason? The federal investment tax credit. Akeena’s management “now assumes that the ITC will not be extended this year,” according to the announcement.

“In the short term, the recession and ITC uncertainty will dampen investments in solar power; in the medium term, the escalating cost of energy will only serve to stimulate demand,” CEO Barry Cinnamon said in a written statement. “In the meantime, we will continue to promote the benefits of solar power while applying strict cost discipline to managing our business.”

Brian Yerger, a research analyst with Jesup & Lamont, called Akeena’s decision to reduce guidance “prudent.”

After all, the company is getting hit with the tax-credit uncertainty, the subprime credit crunch and the economic downturn, all at the same time, he said.

Customers are backing away from projects that might not be completed by the end of the year, because the penalty of any delay could amount to a 30-percent increase in cost for commercial projects, if the tax credits aren’t renewed, he said.

And the downturn in the economy, especially in the housing market, has reduced the equity that homeowners can use to invest in solar power, he said.

Real Goods may be suffering from the coincidence of going public on the same day that Akeena, the largest public solar installer in the United States, missed its earnings, he said.

“It’s just bad luck,” Yerger said. “If Real Goods had come out yesterday, it might not have been down. It just came out on a day when Akeena had bad guidance, which may have created a ripple effect and given it a bad time.”

The bad influence could continue for a little while, as Mark Cox, CEO of the New Energy Fund, predicted that Akeena could drop to $4 per share and stay there “for a bit.” As it is, the stock is 68 percent off its 52-week peak of $16.80 per share, set on Jan. 7.

“In this environment, you get punished, especially if you have not held up,” said Cox, who said his fund previously owned Akeena shares, but sold them at $16 per share. “Akeena Solar hasn’t held up.”