I've heard recently that storage batteries are good for power outage preparedness, but is that really true?
Is it okay to add an ENE-FARM and storage battery to a solar power system?
A thorough explanation of optimal combinations of ENE-FARM, storage batteries, and solar power systems, by manufacturer.
Even those who live in an all-electric home are likely familiar with the term from TV commercials.
ENE-FARM is a gas water heater that generates electricity when boiling water.
We will compare connecting an ENE-FARM to a storage battery with connecting it to solar power.
Hello, I'm Imai from Seiko Denki.
I've been designing residential electrical systems in Nagoya, Japan Prefecture, for about 20 years.
I mainly focus on residential storage batteries, solar power systems, V2H, and smart homes.
We have completed over 500 design and construction projects.
Table of Contents
Types of Water Heaters
・EcoJozu
・EcoCute
・ENE-FARM
Differences between ENE-FARM and Other Models
Power Generation Capacity and Market Prices of Each Model
Can ENE-FARM and Solar Power Generation Be Used Together?
What are the Benefits of Adding a Storage Battery to ENE-FARM?
Created April 30, 2021
Updated April 29, 2025
1. Types of Water Heaters
There are many similar names for water heaters, so let's first clarify them.
・EcoJozu
As of 2021, most gas water heaters are EcoJozu. This is a standard gas water heater.
・EcoCute
This is a water heater that uses electricity to heat water. Working like an air conditioner, hot water is generally generated at night (with a plan that offers lower electricity rates at night), stored in a tank, and used when needed. Compared to gas water heaters, hot water generation costs are lower, but the appliance itself is more expensive.
・ENE-FARM
This is a fuel cell, just like the one used in Toyota's Mirai FCV.
For more information on the power generation method, please see the link below.
How ENE-FARM (Residential Fuel Cell) Works | Japan Gas Association
Here's how ENE-FARM works.
Link
www.gas.or.jp
This system, called "cogeneration," generates electricity and heat when hydrogen and oxygen are chemically reacted to produce water, providing both electricity and hot water simultaneously.
A tank is attached to regulate the amount of power generated and stores the hot water produced during power generation. As of 2021,
The Panasonic model generates power when electricity is used.
The Aisin model generates power 24 hours a day.
Both models generate 700W of power under normal conditions and are equipped with a backup water heater, so even if the tank runs out of hot water, you can still provide hot water without running out, just like a hot water EcoCute.
During a power outage,
Panasonic units either stop generating power or, if there is a 100V power source, continue generating power from gas, providing a 500W/hour emergency power supply.
Aisin units are constantly generating power except for one downtime per month, so unless there is an unfortunate power outage, they will continue to provide a 700W/hour emergency power supply during a power outage.
2. Differences between ENE-FARM and other models
EcoCute, which generates hot water using electricity, and ENE-FARM, which generates hot water using gas,
are functionally completely different.
EcoCute does not generate electricity.
How is it different from solar power generation?
Solar power generation generates power from sunlight, so there are no power generation costs.
Ene-FARM generates power from gas, so there are gas costs involved when generating power.
Since ENE-FARM also functions as a hot water heater,
it's difficult to simply compare it to solar power generation.
However, since there's not much difference in the amount of electricity generated by solar power generation and ENE-FARM,
when comparing installing EcoJozu and solar power generation with installing ENE-FARM alone,
the difference is simply the installation cost.
That said, solar power generation is advantageous because there's a system (the Feed-in Tariff Act) that allows electric power companies to purchase excess electricity at a higher price.
The next difference is the timing of power generation.
Solar power generation only occurs when the sun is out.
The amount of power generated is greatly affected by weather, season, and time of day.
Aisin's ENE-FARM generates power 24 hours a day, so it's not affected by weather, season, or time of day.
3. Power Generation and Market Price of Each Model
- Panasonic ENE-FARM: Market Price: ¥900,000-¥1,300,000
0.7kW x 7 hours x 365 days = 1,788 kWh
- Aisin ENE-FARM: Market Price: ¥1,500,000-¥2,000,000
0.7kW x 24 hours x 353 days = 5,930 kWh
- Solar Power Generation (5 kW): Market Price: ¥1,000,000-¥1,500,000
JPEA's Annual Power Generation (Aichi Prefecture): 1,095 kWh x 5 kW = 5,475 kWh
*Regional annual power generation information is listed below.
http://www.jpea.gr.jp/pdf/011.pdf
When you add the cost of a water heater to solar power generation, the cost benefits become similar.
So, what if storage batteries were installed on each?
Solar Power Generation and Storage Batteries
Solar power generation is heavily affected by time and season, so when calculating the self-consumption capacity to minimize selling, the unstable solar power output necessitates a larger storage battery capacity.
ENE-FARM and Storage Batteries
Aisin's units generate power 24 hours a day, so if you calculate the surplus power during periods of low electricity use and charge the storage battery with it, that comes down to two periods: night and day. The storage battery can be charged twice a day with a smaller capacity. Since it can be charged and discharged as planned, there is no fluctuation.
4. ENE-FARM and solar power generation can be used together.
In terms of equipment superiority, Aisin's ENE-FARM has begun to win, but in terms of cost benefits, there are pros and cons.
As of 2021, fluctuations in purchase prices due to dual generation under the solar feed-in tariff system have been eliminated, and self-consumption over selling and using the generated electricity over selling have become more advantageous.
Since 2020, there has been an increase in combining solar power generation and ENE-FARM systems to match the amount of electricity used at home.
We'll introduce combinations tailored to your needs.
Careful consideration is important when building a new home, and for existing homes, actual utility bills are especially clear. Consider future changes for your family, compare electricity and gas bills, and consider power outage countermeasures in the event of a disaster.
・For homes over 10 years old looking for power outage countermeasures:
ENE-FARM (Panasonic) + 5.6KWh storage battery
You can reduce your utility bills by replacing your water heater. (Not available in areas with propane gas.)
During a power outage, the ENE-FARM can be started from the storage battery, and the storage battery can also be charged from the ENE-FARM.
・For a fully equipped home with the future in mind:
ENE-FARM (Aisin) + 3KW solar power generation + 12KWh storage battery
A shelter house that allows you to live in almost any weather, both normal and during power outages, is possible.
It will also have enough charging capacity to accommodate electric vehicles in the future.
Solar power generation, storage batteries, and ENE-FARM each have their own advantages. We recommend comparing them based on the amount of electricity and gas you currently use.
What are the benefits of adding a storage battery to ENE-FARM?
I recommend Aisin's ENE-FARM and a small-capacity storage battery. However, connecting to the grid can be difficult under normal circumstances and during power outages, and there are only a limited number of models that can be successfully connected.
As with the Ecowill (a gas-powered water heater) that came before ENE-FARM, compatibility with the storage battery is extremely important.
If you're wondering what kind of storage battery is right for you, please leave a comment on this blog. If there are any privacy concerns, please send us a message and we'll answer any questions you may have.
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