In the field of solar backup energy storage, lead-acid batteries dominate the small and medium-sized PV market with superior cost performance. Compared with lithium batteries, they have lower unit energy storage cost and lower initial investment, without requiring complex battery management systems. Featuring mature technology, low failure rate and strong impact load resistance, they stably handle sudden power loads of PV systems. They are widely compatible with household rooftop PV, outdoor small PV equipment and rural off-grid PV stations to realize excess power storage and emergency backup power. Despite limited cycle life, their high stability, low cost and easy maintenance make them an economical and practical preferred choice for solar backup power.