Which is more suitable for home energy storage system, Li-ion battery or lead-acid battery?

According to foreign media reports, in the past, most of the residential solar energy users who deployed the battery energy storage system used lead-acid batteries, especially the batteries completely separated from the grid, but in the past few years, this situation began to change, with the residential energy storage system using more and more lithium batteries. So, which is more suitable for energy storage system, lithium-ion battery or lead-acid battery? Here is an overview of the advantages and disadvantages of both.            Application of lead-acid battery            Since the 1970s, lead-acid batteries have been used as backup power for residential solar power facilities. Although they are similar to traditional automotive batteries, batteries used in residential energy storage systems are called deep cycle batteries because they discharge and charge more than most automotive batteries.            Traditionally, lead-acid batteries cost less than lithium-ion batteries, making them more attractive to residential users. However, their working life is much shorter than that of lithium-ion batteries.            Comparison of cycle life of lead-acid battery and lithium-ion battery in fixed energy storage system            The working life of lead-acid battery is lower than that of lithium-ion battery. Although some lead-acid batteries charge and discharge as many as 1000 times, lithium-ion batteries charge and discharge between 1000 and 4000 times.            Most lead-acid batteries have a service life of about 5 years and a corresponding warranty period. Therefore, in the overall service life of solar power generation facilities, residential users will have to replace lead-acid batteries many times.            The energy storage efficiency of lead-acid battery is lower than that of lithium-ion battery and other energy storage technologies. Because of their low efficiency, they can't charge or discharge as fast as the lithium battery energy storage system.            The discharge capacity of lead-acid battery is low, which means that consuming too much energy will lead to the rapid deterioration of its energy storage capacity. The research of National Renewable Energy Laboratory (NREL) found that 50% of energy released in lead-acid battery can make it complete 1800 charging and discharging before the energy storage capacity drops significantly. If discharge to 80% capacity, it can only withstand 600 charges and discharges, and then its capacity will be significantly reduced.            Because the energy storage efficiency of lead-acid battery is relatively low and can not discharge completely, lead-acid battery needs more energy storage capacity and space than lithium-ion battery. The lead-acid battery is also much heavier than the lithium-ion battery, which requires a stronger bracket and more space than the lithium-ion battery pack.            Lead is a toxic heavy metal. Although it is recyclable, it can still be polluted due to improper treatment.            Application of lithium ion battery            Lithium ion batteries are rapidly becoming the preferred batteries for many power applications, from wireless power tools to laptops and vehicles. More and more residential solar power facilities use lithium-ion battery energy storage system. However, lithium-ion batteries still have some limitations, the first and most important is the high cost.            The initial cost of Li-ion battery is higher than that of lead-acid battery. Tesla's Powerwall energy storage system will cost $5900 or $6600 in the United States in 2018, including supporting hardware. This is a 14kwh battery system that can provide up to 7KW of power at peak demand. The cost does not include the installation cost, which is usually $600 to $2000.            Installation costs of various battery energy storage systems investigated by Lazard            But the cost of lithium-ion batteries is falling rapidly. In the past few years, Lazard has evaluated the cost of various battery energy storage technologies in its energy storage average cost analysis report. In its latest survey report in November 2017, it was found that the installation cost of the lead-acid battery energy storage system supporting the residential solar energy was US $598 to US $635 per kWh. Installation costs for lithium-ion batteries range from $831 to $1089 per kWh.            According to these data, the cost of a 14kwh lead-acid battery is as low as $8372, while that of a lithium-ion battery of the same capacity is as low as $11634. But the low cost of lead-acid batteries hides many other costs, such as shorter working life and higher operating costs.            As time goes on, the cost of each battery system will be very different. Lazard's investigation shows that the energy storage system using lithium-ion batteries costs less per megawatt hour than lead-acid batteries. The cost of a lead-acid battery system per megawatt hour is $1160 to $1239. The cost of a lithium-ion battery system per megawatt hour is between $1024 and $1274.            Bloomberg new energy finance's lithium-ion battery price survey results            Another survey released by Bloomberg new energy finance found that the cost of lithium-ion batteries also continued to decline. Lithium-ion batteries sold for as much as $1000 per kilowatt hour in 2010, and then fell by more than 20% over the next few years. By the end of 2016, the average price of lithium-ion batteries had fallen by $209 per kWh.            However, mark chediak of Bloomberg new energy finance points out that these prices are mainly for batteries provided by electric vehicle manufacturers. "Due to the much lower order volume of developers of fixed energy storage systems, it is expected that the cost of purchasing batteries will be 51% higher than that paid by car manufacturers," he said            For these reasons, it is important to understand the cost of lithium-ion batteries and lead-acid batteries currently used in residential energy storage systems. They can be used as an independent energy storage system or in combination with residential solar power facilities to meet some or