Valve-regulated sealed lead-acid batteries are the mainstream type for current photovoltaic energy storage, widely used in various solar energy storage systems due to their maintenance-free feature and high stability. With excellent sealing performance, they have no electrolyte leakage during operation and require no frequent water maintenance, making them suitable for outdoor and unattended photovoltaic scenarios. They deliver stable voltage output and perfectly match the power generation characteristics of photovoltaic modules, effectively alleviating the intermittency and volatility of solar power. Deep-cycle lead-acid batteries support 80% deep discharge with over 2000 cycle times and excellent overcharge and overdischarge resistance. Their low monthly self-discharge rate of about 5% enables long-term solar energy storage for daily energy storage demands.