NEW YORK ( TheStreet) -- GT Solar ( SOLR), JA Solar Holdings ( JASO), Helix Energy Solutions ( HLX) and Energy XXI (Bermuda) ( EXXI) were top performers this week, while Vestas ( VWRDY), Aventine Renewable Energy Holdings ( AVRW) and LDK Solar ( LDK) eroded substantial ground.Among the advancers, GT Solar topped the charts, jumping 18.2%. Ardour Capital reiterated a buy on the stock on improved prospects from the company's Sapphire business. JA Solar rose 10.5% and Helix Energy Solutions gained 8.3% the week of June 20. Energy XXI (Bermuda) advanced 8.3%. Analysts at Rodman & Renshaw maintained market perform on the stock and observed higher-than-expected production. Other winners were Rosetta Resources ( ROSE) up 7.1%, Brigham Exploration ( BEXP) rose 6.6%, Tesoro Corporation ( TSO) grew 6.6%, Holly Energy Partners ( HEP) added 6.6%, Cheniere Energy Partners ( CQP) gained 6.5%, Unit Corporation ( UNT) improved 6.5%, Atwood Oceanics ( ATW) and TC PipeLines ( TCLP) piled 6.3% each. Bill Barrett Corporation ( BBG) moved up 6.2%. Global Hunter Securities equity analyst Michael Bodino rated a new accumulate on the stock with a 12-month target price of $59 per share. Berry Petroleum ( BRY) gained 6% during the week. Oil States International ( OIS) rose 5.5% after its subsidiary secured a contract from Subsea 7 to supply 27 FlexJoint Steel Catenary Riser terminations and 40 receptacle assemblies for the Guara and Lula NE oilfields in Brazil. Other movers were Oceaneering International ( OII) rising 5.5%, Teekay LNG Partners ( TGP) up 5.2%, Weatherford International ( WFT) rose 5%, and Holly Corporation ( HOC) added 4.7% during the week. STR Holdings ( STRI) advanced 5%. Analysts at Maxim Group rated a new buy on the stock with a price target of $22 per share. PAA Natural Gas Storage ( PNG), Bristow Group ( BRS), Mcmoran Exploration ( MMR) and Dril-Quip ( DRQ) closed the week with gains of more than 4%. Vestas was the top lagger, shedding 13.3%. Citi rated a sell on the stock on stretched valuations. The brokerage says the company could miss its year-over-year order intake growth for 2011 of 7 to 8 GW. Aventine Renewable Energy Holdings declined 5.9% and LDK Solar lost 5.3% during the week. EnCana Corporation ( ECA) erased 4.6%. S&P revised Encana's outlook to negative on closure of PetroChina joint venture. Niska Gas Storage Partners ( NKA) pared 4.2%. UBS lowered its price target on the stock to $19 per share from $20 and maintained a neutral rating on it. Nabors Industries ( NBR) fell 4.2%. Analysts at Raymond James downgraded the stock to market perform from strong buy. Others on the downside were Occidental Petroleum ( OXY) sliding 3.3%, Legacy Reserves ( LGCY) dropping 3.3%, Nexen ( NXY) erasing 3.1%, Frontline ( FRO) losing 2.5% and Imperial Oil ( IMO) eroding 2.1%.