[News] 98% *1 achieved "zero-energy" *2!
"Smart Power Station" - Survey on houses for electric power balance (2015)
*3
November 4, 2015
SEKISUI CHEMICAL CO., LTD.
The Housing Company (President: Shunichi Sekiguchi) of Sekisui Chemical Co., Ltd. surveyed
the achievement status of "zero-energy" of those houses (Smart Power Station) in which residents
actually live. Since October 2013, the Housing Company has been marketing its "Smart Power
Station" series, which turns a standard size house into "zero-energy housing"*2. The "Smart Power
Station" consists of a large capacity photovoltaic (PV) power generating system, a consulting type
home energy management system ("Smart Heim Navi") (HEMS) and a large stationary lithium-ion
storage battery ("e-Pocket").
The survey targeted 166 houses in which the "Smart Power Station" was installed and in which the
residents actually lived. The survey checked the power consumption and power generated by these
houses from October 2014 to September 2015. The survey found that 98% achieved "zero-energy".
This was better than the 66% in our 2014 survey (published in February 2015), where all houses of
our "Smart Heim" were surveyed.
The survey on the power balance in 2014 showed that the users who generated more electricity but
consumed less had achieved "zero-energy". However, residents using the "Smart Power Station"
are seemingly achieving "zero-energy" very easily while leading comfortable lifestyles because they
overwhelmingly generate much more power while consuming it at normal levels.
*1. Total of the ratio of the houses that achieved "zero-energy including appliances" and the ratio of the houses that achieved
"zero-energy without including appliances". (See the graph "Zero-energy Achievement Rate".)
*2. "Zero-energy" or "Zero-energy" house: The houses that use only electricity for energy and do not use any other energy source,
where "power consumption" < "power generated".
*3. This report describes "Energy Balance" as the evaluation at operation (result of living in the house). It is not a report on "evaluation
in the design phase" defined by the requirements, etc. of "Net Zero-energy House (ZEH) Support Project" (related to 2014
Supplementary Budget).
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Survey Results - Significance
１．"Smart Power Station" - 98% achieved "zero-energy".
The "Smart Power Station" consists of a large capacity PV and household storage battery. Its
HEMS correctly controls the electric power demand. As a result, the electricity power balance
was -4,299 kWh/year as an average of all "Smart Power Stations" (The survey for the previous
year showed -2,246 kWh/year for all product types.) In the energy balance for the year, the
electric power sold by a large capacity PV was 344,045 yen (153,106 yen – for the previous
year’s survey), significantly exceeding 120,473 yen of the power purchased (135,979 yen – for
the previous year’s survey) and, as a result, the energy balance for the "Smart Power Station"
was +223,572 yen (+17,127 yen – from the previous year’s survey).
２．Goal to implement future "Energy Self-sufficient Housing" - Validation
～ Preliminary calculation of the "self-sufficient rate" if GREEN MODE operation is
implemented in preparing for termination of FIT
In this survey, the effect of the GREEN MODE*4 (potential future method for storage battery use)
has been calculated. Currently, because "Feed-in Tariff for Renewable Energy" (FIT) is applied
to the PV, the household storage battery is operated in ECONOMY mode*5, (charged with
midnight power). In the future, however, it is expected that the storage battery will be operated
using GREEN MODE (charged with surplus electricity from the PV) to achieve "self-sufficiency".
Therefore, in this survey, we calculated the "self-sufficiency rate" when the storage battery was
operating in GREEN MODE in the "Smart Power Station", and determined that that about half of
the electric power consumed by a house can be provided by the power being generated by the
PV.
*4. GREEN MODE - You can use the power generated during the daytime, you can use the PV surplus power saved during the
night, or you can purchase needed power from an electric company. In this mode, you can live a lifestyle that uses mainly
natural energy generated by in-house power generation.
*5. You can use the power generated by a large capacity PV during daytime, and sell any surplus electricity to the electric company.
You can use the power saved during the night (midnight price) in the morning and at night.
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■ Survey - Outline
Purpose: To validate the power consumption of the "Smart Power Station", generated
power and power balance.
To calculate the potentiality of the "self-sufficiency" of electricity in a house where
a storage battery has been installed.
Target:
Houses that have installed the "Smart Power Station" (all electricity) (Sekisui
Heim) *6 and PV. The power consumption and power generated from October
2014 to September 2015 were investigated.
Region:
All areas of Japan except Hokkaido
Method:
We analyzed the data in the HEMS server.
Valid population: 166 houses (For 70 houses, the effect of the storage battery was
calculated.)
*6. "All electricity" - Definition: A house that does not use electric energy for cooking, hot water or heating, and the total
power consumption is measured by HEMS.
■Survey Result - Summary
１．"Smart Power Station" - 98% achieved "zero-energy".
"Power Balance - Investigation of Houses 2014" published in February of this year showed 66% of
the houses achieved "zero-energy" and 98% of the "Smart Power Station" houses achieved
"zero-energy".
＜Zero-energy achievement ＞
rate>
◆ Category of above graph
In the operation of "zero-energy", the energy consumed by houses is defined as "not
including appliances and cooking" and "Including appliances and cooking"; we
categorized this energy consumed accordingly. We defined "zero-energy including
appliances", and that includes appliances and cooking; "zero-energy not including
appliances" does not include appliances and cooking.
① Power balance is "-4,299kWh/year".
The "Smart Power Station" consists of a large capacity PV and a household storage battery with a
HEMS that correctly controls power demand. As a result, the power balance was -4,299
kWh/year as an average for all "Smart Power Stations" (The previous year’s survey showed
-2,246 kWh/year.)
② Yearly energy balance - "+220,000 yen"
In the energy balance for the year, the electric power sold by the large capacity PV was 344,045
yen (153,106 yen - previous year’s survey), significantly exceeding the 120,473 yen of the power
purchased (135,979 yen - previous year’s survey) and, as a result, the energy balance for the
"Smart Power Station" was +223,572 yen (+17,127 yen - previous year’s survey).
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２．Goal to implement future "Energy Self-sufficient Housing" - Validate
～
Preliminary calculation of "self-sufficient rate" *7 if GREEN MODE operation is
implemented in preparation for the termination of FIT
The "Smart Power Station" actively promotes "zero-energy" and storage battery implementation.
The storage battery is currently operated in ECONOMY MODE (charged with midnight power)
because the "Feed-in Tariff for Renewable Energy" (FIT) is being applied to the PV. In the future,
after FIT has been terminated, the storage battery is expected to be operated using GREEN MODE
(charged with surplus power from the PV) to achieve "self-sufficiency". Then, in this survey, we
calculated the "self-sufficiency rate" when the storage battery was operated in GREEN MODE in a
"Smart Power Station" based on the power consumption data from "Smart Power Station" houses.
We surveyed 70 houses (among a target of 166 houses) in which a household storage battery
(capacity: 5.53 - 7.2kWh) was installed. We calculated the "self-sufficiency rate" and found that
the average house achieved a 26% self-sufficiency rate with a PV, and a 23% rate with a storage
battery. So the total for these self-sufficiency rates (PV and storage battery) is 49%. We
determined that changing the operation method of the storage battery would enable us to supply
half of the power consumed by homes from PV power generation.
*7. The "Self-sufficiency rate" described here means how much power a "PV + storage battery" can provide for a home; that is,
how much power the home can save without receiving power from an energy company.
Self-sufficiency rate = (1 - Purchased energy / Consumed energy) x 100%
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