In the field of off-grid photovoltaic energy storage, 12V lead-acid batteries are classic products balancing cost performance and practicality. They feature mature technology, low failure rate, low procurement and maintenance costs, as well as simple installation and commissioning without complex supporting equipment, enabling ordinary users to build small photovoltaic energy storage systems independently. However, they have obvious shortcomings such as low energy density, large size and weight, shorter cycle life than lithium batteries, and accelerated aging caused by deep discharge. Thus, they are more suitable for small and medium-power off-grid scenarios with limited budgets and convenient maintenance, rather than high-power long-term energy storage. Standard use gives full play to their practical value to meet basic off-grid photovoltaic power demand.