LONGSUN SOLARELECTRIC CO.,LTD strictly selects the raw materials of circle solar panel-why are solar panels good. 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.. In order to deliver satisfactory service at Longsun Solar Panel, we have employees who really listen to what our customers have to say and we maintain a dialogue with our customers and take note of their needs. We also work with customer surveys, taking into consideration the feedback we receive..