The relationship between smart meters and stationary batteries

At present, Japan adopts a system of switching electricity prices between day and night called 'time-of-day light'. For example, Tokyo Electric Power has charge plans called 'Economic Night 8' and 'Economic Night 10'. The former will cover 8 hours between 11pm and 7am, and the latter will charge between 10pm and 8am. 10 hours is set as the low electricity price period at night. In terms of electricity prices per kilowatt-hour (kWh), the former is 30.87 yen during the day and 11.82 yen at night, while the latter is 33.6 yen during the day and 12.06 yen at night. Therefore, the price difference per kilowatt-hour between day and night is 19.05 to 21.54 yen.　　 For the procurement of smart meters, Tokyo Electric Power and Japan’s Atomic Energy Damage Compensation Support Agency issued a request for proposal (RFP: request for proposal) on November 19, 2012, and began to collect communication function proposals. The proposal is scheduled to be accepted by the end of February 2013, and the supplier will be determined from March to April 2013. Tokyo Electric Power plans to introduce 17 million smart meters by 2018 and 27 million smart meters by 2023 in its jurisdiction to complete the introduction to all households in need.　　 A huge change brought about by the popularization of smart meters is that a dynamic pricing system based on electricity supply and demand will become easier to implement. Dynamic pricing is to increase the price of electricity during the daytime in summer and evening in the winter when there is a shortage of electricity, and reduce the price at night when the electricity is surplus. At present, Japan’s Kitakyushu City in Fukuoka Prefecture and Toyota City in Aichi Prefecture are conducting empirical tests on this.　　 If the fixed storage battery wants to enter ordinary households and allow users to recover the cost within 10 years, what kind of price is feasible? For an ordinary household with a daily electricity consumption of 10 degrees, if you set a battery with a capacity of 4kWh to charge at night and use up all the electricity during the day, you can save about 80 yen in electricity bills every day. In this way, about 29,200 yen will be saved each year, and about 292,000 yen will be saved in 10 years. In other words, the price of a stationary battery with a capacity of 4kWh must be less than 300,000 yen to recover the cost within 10 years. And this price also includes the price of frequency converters and converters used to convert electricity. In other words, the price of the entire system must be less than 75,000 yen per kWh.　　 However, with the popularity of smart meters, the situation will change slightly if dynamic pricing is introduced. For example, if electricity is set at 100 yen per kilowatt-hour during the daytime in summer and in the evening in winter, and 10 yen per kilowatt-hour when electricity is surplus in the middle of the night, the price difference will be 90 yen. If you use the power stored at night in the storage battery for 4 hours from 1 pm to 5 pm in the summer two months and from 4 pm to 8 pm in the winter months, you can save 90 yen × 4 kWh × 4 months u003d 43,200 yen. In addition, if the pricing for other months is the same as the above-mentioned 'time-of-hours lightsMonth) u003d 62,400 yen (Note to the author: If the introduction of solar cells goes smoothly in the future, the power shortage in summer and winter evenings may become a bigger problem than the power shortage during the day in summer).　　 In this way, if you want to recover the cost in 10 years, it can be achieved as long as you can purchase a 4kWh battery at a price of about 600,000 yen. In other words, the price of the entire system is 150,000 yen per kWh. If it can achieve 75,000 yen per 1kW, the cost will be recovered in 5 years, and it is expected to spread rapidly.