This week, these five stocks have the worst ratings in Cash Flow, one of the eight Fundamental Categories on Portfolio Grader.

MEMC Electronic Materials (NYSE:WFR) manufactures and sells wafers and related products to the semiconductor and solar industries. WFR also gets F’s in Earnings Momentum, Analyst Earnings Revisions, Equity, Operating Margin Growth, and Sales Growth. Shares of the stock have declined 32.5% since January 1. This is worse than the S&P 500, which has seen a 10.1% increase over the same period. For more information, get Portfolio Grader’s complete analysis of WFR stock.

LDK Solar (NYSE:LDK) manufactures multicrystalline solar wafers. LDK gets F’s in Earnings Growth, Earnings Momentum, Analyst Earnings Revisions, Equity, Operating Margin Growth, and Sales Growth as well. Shares of the stock have declined 65.6% since January 1. For more information, get Portfolio Grader’s complete analysis of LDK stock.

Suntech Power Holdings (NYSE:STP) is a solar energy company that designs, develops, manufactures and markets PV cells and molecules. STP also gets F’s in Earnings Growth, Earnings Momentum, Analyst Earnings Revisions, Equity, Operating Margin Growth, and Sales Growth. The price of STP is down 50.6% since the first of the year. For more information, get Portfolio Grader’s complete analysis of STP stock.

ATP Oil & Gas (NASDAQ:ATPG) is engaged in the acquisition, development and production of oil and natural gas properties in the Gulf of Mexico and the U.K. ATPG gets F’s in Analyst Earnings Revisions and Sales Growth as well. Since January 1, ATPG has fallen 95.1%. For more information, get Portfolio Grader’s complete analysis of ATPG stock.

Hanwha SolarOne (NASDAQ:HSOL) manufactures photovoltaic (PV) cells and modules, provides PV cell processing services to convert silicon wafers into PV cells, and supplies solar system integration services in China. HSOL gets F’s in Earnings Growth, Earnings Momentum, Analyst Earnings Revisions, Equity, Operating Margin Growth, and Sales Growth as well. For more information, get Portfolio Grader’s complete analysis of HSOL stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.