LONGSUN SOLARELECTRIC CO.,LTD strictly selects the raw materials of high performance solar panels-polycrystalline solar panel. We constantly check and screen all incoming raw materials by implementing an Incoming Quality Control - IQC. We take varies measurements to check against collected data. Once failed, we will send the defective or substandard raw materials back to suppliers.. To establish Longsun brand and maintain its consistency, we first focused on satisfying customers' targeted needs through significant research and development. In recent years, for example, we have modified our product mix and enlarged our marketing channels in response to the needs of customers. We make efforts to enhance our image when going global.. At Longsun Solar Panel, we offer expertise combined with personalized, one-on-one technical support. Our responsive engineers are readily accessible for all of our customers, large and small. We also provide a wide array of complimentary technical services for our customers, such as product testing or installation..