Increased Reliability of Power Supply Drives Further Development of Residential Energy Storage

Frequent accidents prompt the maintenance of energy storage for stable power supply. Large-scale blackout incidents, with sudden impacts affecting over 100,000 people and outage durations exceeding 1 hour, occur repeatedly on a global scale. Countries like the United States, Canada, Australia, Brazil, and India experience the highest frequency of such incidents, typically characterized by vast territorial coverage, extensive power grid spans, and complex operational conditions. Aging facilities in North American power grid systems and insufficient investments in power infrastructure in Asia, Africa, and Latin America contribute to frequent power outages and shortages. This is compounded by the prevalence of extreme weather events such as climate warming, cold waves, tornadoes, high temperatures, and droughts, further driving the essential need for emergency backup power among local residents. Residential energy storage provides emergency power during power plant accidents or extreme natural disasters, enhancing electricity stability. Distributed solar photovoltaic (PV) and residential energy storage are still in their early stages of development globally, with most regions having a penetration rate of less than 10%, indicating significant room for growth.

According to BNEF statistics, residential demand accounts for roughly 20%-30% of global energy storage applications, significantly higher than industrial and commercial sectors. Integrated PV storage units (all-in-one units) often utilize direct current coupling for higher comprehensive efficiency. Currently, for various residential energy storage demands, residential energy storage systems can mainly be categorized into integrated PV storage units and split energy storage units. Integrated PV storage units, as the name suggests, integrate PV inverters and bidirectional inverters into a single integrated system internally. The integrated mode typically employs direct current coupling, enabling plug-and-play functionality and realizing an integrated "PV + storage" solution, suitable for synchronously installing incremental residential PV and storage systems. On the other hand, split energy storage units are suitable for existing residential PV systems and typically utilize alternating current coupling internally, facilitating connection with existing PV inverters. Direct current coupling mode exhibits significantly higher efficiency compared to alternating current coupling mode under the daytime generation and nighttime consumption model, aligning with the electricity consumption habits of most households, with efficiencies approximately 95% and 90%, respectively.

Integrated PV storage units are highly integrated, effectively reducing soft costs. NREL data shows that hardware costs account for less than 50% of the total cost of residential energy storage systems, and integrated PV storage units, due to their high integration characteristics, eliminate the need for separate installation of PV inverters. On the one hand, this reduces hardware costs, and on the other hand, it saves one-time equipment investment, simplifies installation, reduces installation costs, and facilitates after-sales maintenance, effectively reducing subsequent soft costs. According to our calculations, integrated PV storage units can save approximately $155/kWh compared to split systems. Furthermore, according to BNEF forecasts, the future reduction in soft costs will be far lower than that of lithium batteries and inverters. In situations where the hardware equipment costs are similar to split systems, the soft cost advantage of integrated units will be further highlighted in the future.