NEW YORK (TheStreet) -- BP plc (BP - Get Report), Total (TOT - Get Report), China Petroleum & Chemical (Sinopec) (SNP - Get Report), Yingli Green Energy Holding (YGE), LDK Solar (LDK) and ReneSola (SOL - Get Report) are among the cheapest energy stocks.The current upswing in crude oil prices may support energy stocks to outperform broader markets during the upcoming weeks. Year-to-date, the S&P 500 Index gained 4.6%, while the S&P 500 Energy Index surged 12.0%. In the current market environment of volatile oil prices, the following 10 energy stocks are trading at deep discounts, offering bargain opportunities to investors. These stocks are selling at price-to-projected-earnings ratio of less than 9, while the S&P 500 index is trading at a PE ratio of 15.6. In comparison, Exxon Mobil ( XOM), Chevron ( CVX), ConocoPhillips ( COP), Apache ( APA) and Suncor Energy ( SU) have forward price-to-earnings multiples in the range of 9.3-18.5. The following 10 energy stocks have buy ratings in the range of 40%-82% and are expected to gain up to 56% over the next 12 months with a mean upside value of around 21%, according to analysts polled by Bloomberg. The stocks are ordered from cheap to cheapest based on forward earnings multiples.