ReneSola Ltd, a China-based solar wafer producer, joined a slew of companies in cutting its quarterly revenue and gross profit margin view, as lower subsidies in major European markets weigh on sales and prices.

ReneSola shares, having nearly halved their value this year, fell 8 percent to a low of $4.29 on Tuesday. Other solar stocks, including those of First Solar, Suntech Power, Trina Solar, Yingli Green Energy and GT Solar International, were also down.

Solar companies such as STR Holdings, China Sunergy Co and SunPower have already pointed toward shrinking profit margins or sales.

"Our industry checks continue to suggest prices continue to weaken and demand remains weak," Credit Suisse said in a note.

ReneSola Chief Executive Xianshou Li said: "We experienced greater-than-expected price declines in our core wafer business and supporting module business."

Wafer business pulled in about 57 percent of its net revenue last year. Europe -- where governments are slashing subsidies on renewable energy -- contributed more than 35 percent.

Goldman Sachs last week cut its 2012 average selling price (ASPs) outlook for Chinese modules to $1.15 per watt from $1.32. Wafer ASP expectation was lowered by 3 cents to 45 cents per watt.

ReneSola, which also cut its total solar wafer and module shipments forecast, now expects its second-quarter gross profit margin to be in a 17-19 percent range, down from its previous outlook of 25-27 percent.

"ReneSola is one of the more cost-competitive companies" Morningstar analyst Stephen Simko said. "So if they are seeing their margins slice in half ... for less efficient companies, especially the equities that trade outside the US that have far lower margins, it seems pretty darn likely that this is going to be a quarter of losses."

To lower the cost of making solar products, companies like JA Solar Holdings and ReneSola have already started in-house production of key raw materials such as polysilicon and wafers. They have also looked at acquisition.

"We will maintain our focus on our core wafer business, as well as horizontal expansion to reduce costs, and will continue selling modules to our customers," CEO Li said.

ReneSola cut its April-June revenue forecast to $235-$245 million from $280-$300 million. Analysts were looking for $287 million, according to Thomson Reuters I/B/E/S.

"I don't think this is the last piece of negative information or the last earnings outlook reduction we're going to see," Morningstar's Simko said.