On the use and testing: The product is used under sufficient light conditions. STC standards need to meet the following conditions: Atmospheric pressure 101kPa Solar irradiance 1000W/m² Module temperature 25℃ Air quality AM1.5 So versatile, these mini solar panels are ideal for use in science projects and electronic applications. Perfect for using as a convenient charger for small DC batteries (great for taking with you when camping or fishing!), the compact solar cells are also ideal for DIY and home projects including creating solar lawn and landscape lights or powering small motors to create solar toys. Tips: -The product has a film on the surface, it is recommended to tear it off before use -Multiple pieces in parallel and series can increase power Storage Battery ----relation---Solar Panel 1.2V------------------------2.0V 2.5V 2.4V------------------------3.5V 4.0V 3.6V------------------------5.0V 6.0V 6.0V-----------------------7.5V 9.0V