These Are the Important Factors to Consider When Purchasing a Power Storage System for Your Home

Power outages are common during the rainy season in Japan.

It’s full-scale heavy rainy season over the Japanese archipelago right now. This is on top of the new coronavirus disease continuing to affect the region. From the experience of large-scale disasters in the past, local governments and companies in Japan are constantly reviewing disaster preparedness, but it is actually difficult to avoid crowds in evacuation centres. What should we do if the government issues an evacuation advisory in a situation in which it is necessary to avoid
San-mitsu (Three Cs: Closed spaces with poor ventilation, Crowded places with many people nearby, and Close-contact settings such as close-range conversations)? Therefore, we talked to a battery maker, Eliiy Power, about measures against blackouts.

Disaster preparedness in the corona era: Distributed Evacuation and Strengthening Measures at Home

When a natural disaster occurs while taking measures against corona infectious diseases, the key points are Distributed Evacuation and Strengthening Measures at Home. Distributed Evacuation means that not all local residents in an area gather in a large evacuation centre such as a school gymnasium, but instead evacuate to a small evacuation centre such as a nearby public hall, an acquaintance’s house or a relative's house.

If your home is in danger, you must of course evacuate. However, if your home is safe, it is also important to have an option not to go to an evacuation centre from the viewpoint of avoiding 3Cs. To that end, it is necessary to further strengthen measures against natural disasters and prepare at home to respond to the disasters.

Eliiy Power explains Power Storage System, a saver in case of power failure

One of the personal countermeasures against disasters you can take at home is to prepare for a power outage. Recently, many natural disasters have caused serious damage due to power outages. The 2018 Hokkaido Eastern Iburi Earthquake caused a large-scale power outage throughout Hokkaido. Furthermore, in 2019, Typhoon No. 15 and Typhoon No. 19 caused great damage to various parts of Japan.

In particular, Typhoon No. 15 caused a great deal of damage due to power outages, causing a temporary power outage of approximately 930,000 houses, mainly in the Kanto region. The number of power outages in Chiba Prefecture reached 640,000, accounting for 70% of the total. It was 15 days after the power outage occurred that the outage was officially resolved. However, in fact, there were cases in which "hidden outages" continued due to problems with individual service lines for households and other electrical equipment, and the power outages became a longer problem.


A portable power storage system that can be installed in the living room and used easily

Under such circumstances, attention is focused on the power storage system that enables the use of electricity even in the event of a power outage. Eliiy Power, a battery maker, says, "we can take measures depending on the living environment, whether you are building a new house, already started building a house, purchasing an apartment or renting a house." Power shared information about disaster countermeasures using the electricity storage system by dividing into three patterns: new housing, existing housing, and rental housing.

New Housing

In recent years, housing makers have been promoting Smart Houses. The houses use solar power to save energy, aiming for self-sufficiency, but they will also be houses with disaster countermeasures that are resilient to blackouts during natural disasters. For example,
Daiwa House Industry sells Houses Prepared for Disasters that employ an all-weather three batteries coordination system. The all-weather three batteries coordination system is a system that combines a solar cell and a fuel cell that produce electricity and a battery that stores electricity. It is capable of securing electricity, heating and hot water supply for about 10 days even in rainy weather.

Existing Housing

Portable power storage system
POWER YIILE 3 is useful in case of a power failure

For those who do not plan on building a new house, the portable emergency power storage system is recommended. Usually, it takes several months for a residential power storage system to be installed due to unique contracts with a power company and construction of the equipment. The portable system is worth looking into because it can be charged simply by removing it from the box and plugging it into an outlet. The emergency power storage system can be purchased from battery manufacturers' EC sites.

Rental Housing

Compact wall-mounted power storage system "POWER YIILE HEYA." The capacity is 1.3kWh.

Recently, rental condominiums and apartments that are resilient to disasters have started popping up. Daiwa House Industry, for example, launched rental houses in 2016 with household lithium-ion batteries installed in all units. The Daiwa House Industry is planning to expand the variety of products that take into consideration the safety and security of residents in case of a disaster.  The company also launched rental houses equipped with a wall-mounted type power storage system in 2019.

They say that the power storage systems for disaster countermeasures are increasingly installed. They are usually already installed when building a new house. If there is a system that allows you to live without relying on the normal electrical system for 10 days by linking 2 cells and a battery, like Daiwa House Industry, you can work without stress at home even during a power outage. Because of the epidemic of the new corona disease, more and more companies are introducing remote work systems. In the near future, it may be necessary to prepare an environment where people can work at home even in case of a disaster.


How much is the power storage system? How to purchase it at a good price

When considering the installation of a power storage system, one of the main concerns is the price. The lithium-ion battery itself is still an expensive product, so it costs about ¥700,000 for the wall-mounted type (1.3kWh capacity) and ¥900,000 for the portable type (2.5kWh capacity). Household batteries cost about ¥1.8 million with a capacity of 5.4 kWh and abou ¥2.8 million\ with a capacity of 10.8 kWh, which is even more expensive.

Looking at the prices, many might think that “it is not an easy thing to do,” but in addition to leasing sales that can be introduced at an initial cost of ¥0, energy-saving and environment-related subsidy systems are increasingly promoted in national, prefectures, and municipalities level. By making use of these subsidies, you can purchase the battery system relatively cheaply.

So now that you know how much it costs to set up, how do you choose a power storage system

Finally, we asked them to share information on three key points when choosing a power storage system. The first is safety. Since the power storage system stores hundreds of times more energy than a mobile phone battery, there is a risk of causing a serious accident such as a fire if mishandled. It is important to select highly safe products in case of natural disasters or unexpected accidents.

The second is product life cycle. When a battery reaches the end of its life, its capacity and performance drop significantly. It is recommended to consider not only the initial cost but also the total cost from purchase to disposal considering the life cycle. Eliiy Power said, "a power storage system is a facility that should be used for more than 10 years. Selecting a power storage system equipped with a high-performance battery that can withstand outdoor use for a long period of time will reduce the life cycle cost after 10 years. When you see it, it's the best deal."

The third is temperature characteristics. The power storage system is very sensitive to the surrounding environment such as temperature and humidity. Choosing a power storage system with excellent temperature characteristics enables us to install it outdoors in cold districts and on the south side of the house where it can be hot due to direct sunlight, thus making effective use of space. With regard to disasters, there are many things that cannot be understood until they happen. However, at the same time, it often happens that effective responses cannot be made after the disaster. This rainy season, think about your home disaster preparedness. Are you ready for anything?


Provided by Japan Walker™, Walkerplus™, and Tokyo Walker™ (07 July 2020)

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