The battery capacity determines the amount of energy that can be stored. Built-in 2400 mAh rechargeable lithium-ion battery makes this light brighter and more long-term. We also increased the conversion rate by 50% using SunPower solar panel that is 35% higher than other products in the market. It could light up 8-12hours with sensor mode and more than 12 hours with dim mode, which is enough to light up the night