12V lead-acid batteries are the most widely used energy storage devices in small and medium off-grid photovoltaic energy storage scenarios. Featuring mature technology, low cost and strong compatibility, they are ideal for low-voltage energy storage applications such as household small photovoltaic systems, outdoor lighting and power supply in remote villages. Compatible with conventional PWM and MPPT solar controllers, they have a standard charging cut-off voltage of 14.4V-14.8V and a discharge protection voltage of 11.8V, matching the power generation characteristics of off-grid photovoltaic systems. Compared with lithium batteries, they have lower initial investment and proven stability, requiring regular maintenance with a recommended discharge depth within 50%, making them a cost-effective choice for off-grid energy storage.