Recently power system efficiency & stability are emphasized following the expanded supply of smart grid & new & renewable energy
and therefore ESS is highlighted as an essential device that is easy to control power supply/demand and improve power quality.
Accordingly E&H is actively promoting ESS biz that can innovate energy efficiency.

ESS's major purpose for utilization

  • electricity load control

    controlling electricity load by supplying
    the electricity, at the peak time, stored
    previously when demand was less.

  • electricity quality enhancement

    In case of electricity produced by new and
    renewable energy, its fluctuation rate of
    power is high. In this case, it may cause
    a confusion of electrical grid during quick-
    charging of electric car, and therefore it is
    used for frequency control purpose.

  • supply stability enhancement

    Use the power stored by the receptor
    system during unexpected blackout or
    peak time zone when the rate is very

ESS conceptual diagram

Application Field

  • Power supply for air conditioning,
    heating & home appliance

  • Power for electric machinery
    in the yacht & camping car

  • When electricity is not supplied
    due to blackout, etc.

  • Reducing energy oil cost
    for refrigerator

  • Power supply
    for isle & military zone

  • All sorts of place in the isle,
    mountain, submarine, etc.

Classification by Application

Product is classified according to the size of ESS such as power output, energy, etc. and the hours of use.

Class Application Output Discharge
· Maintain power grid frequency
· Improve power quality
· backup power
MW +
~30 Min
· New & renewable energy
· Replace gas turbine
Energy Storage
Load Leveling · Large energy storage
· Secure stability of New &
  renewable energy power amount
MW ++
· Extra power amount
  at off-peak time
Energy Storage
Community ESS · Backup power per village
· Small size Peak Improve
  shifting power quality
· Smart grid
· New & renewable energy for home
· Expand EV
Energy Storage
Residential ESS ·Backup power at home
·PV Integration
· Home New & renewable energy
· Expand EV
. Energy emission zero house

Characteristics of Battery Overall Analysis

Class Lead Acid
(Nickel, Cadmium)
(Nickel, Manganese)
Li-Polymer B/T
(Lithium polymer battery)
Cell standard voltage 2.0 1.2 1.2 3.7
Max. charging voltage 2.4 1.5 1.6 4.2
Charging temp. change △3℃ △7℃ △15℃ △5℃
Weight energy density [Wh/kg] 40 65 80 >150
Bulk energy density [Wh/l] 90 160 240 >350
Temp. characteristics -20℃ ~ 45℃ -20℃ ~ 45℃ -10℃ ~ 50℃ >-20℃ ~ 45℃
Memory effect No Very large Common >No
Self discharge [%/Mon] 10 ~ 15% 20 ~ 25% 15 ~ 20% >2 ~ 3%
Storage property 2 Yr 1 Yr 6 Mon Over 5 Yr
Environmental friendly Weak Weak Common Excellent
cost Excellent Acceptable Economic High

Current situation ESS at home and abroad

There is political support to promote ESS supply at home & abroad.
In Korea, there was recently a pre-announcement of partial revision of the Enforcement Decree of ‘Act on the Promotion of the Development,
Use and Diffusion of New and Renewable Energy’ by MOTIE,
which is focused on adding REC weighted value further in case of installing
new & renewable energy system together with ESS. US California State obliged installation of ESS up to 5% of power supply to power company
by 2020 and provides subsidy for this. Also Japan & Germany are promoting ESS construction by providing subsidy.

  • • Compulsory ESS installation

    - Obliged to supply 2.25% (2014), 5% (2020) level of power supply
    - Obliged to submit purchase support form for 1% capacity ESS
      of 2020 estimated max. power to power company.

    - Obliged ESS for fixed rate of peak power amount.

    • For ESS construction & operation,
      they provide $2,000/Kwh subsidy

  • Remark: California State Government.
  • • ESS demonstration project and supply investment led by DOE

  • Remark: Federal Government

  • • They provide max. 1/3 of ESS construction cost.

    - They support 1Mil¥ for home ESS, 0.1Bil¥for corporate ESS
      (¥21Bil budget in total)

    • They provide $2,000/kwh subsidy
       for ESS construction & operation

  • Remark: hosted by Japan METI
  • • They provide 2/3 of ESS construction cost
    • They provide 2/3 of ESS construction cost(Saitama Pref.)

  • Remark: Hosted by each rural autonomous body

  • • They support 30% of construction cost for ESS connected
      with PV generation

  • Remark: Implemented from Feb., 2014

  • • Reviewing on ESS installation obligation

    - Newly constructed building consuming over 1,000kwh
  • Remark: Implemented from 2015
  • • Establishing ESS comprehensive promotion plan

    - KEPCO established \ 650Bil execution plan for ESS investment
  • Remark: Hosted by KEPCO

Need for ESS

Smart grid & New & renewable energy is highly spotlighted owing to the increased demand for global energy.
The best way to maximize usage efficiency of smart grid and new & renewable energy is ESS only.

  • It can reduce peak load and energy cost by utilizing energy at peak time which have been stored from PV system at non-peak time.
  • Power demand can be autonomously adjusted by necessity.

ESS Type

ESS can be classified
into into medium-large size & home use by applications.

Application Utilization Capacity
home use
Village-based backup power
For housing Backup power at home
For commercial use Efficient utilization of demand power
For industrial use Demand & supply adjustment
For generation use

Merit of ESS

ESS is an electricity storing battery with which the power company can supply
power to consumer at peak time by saving extra electricity into large capacity battery at dawn when power consumption is lessening.

Competitive advantages of ESS against other energy storage device is as follows.

1) Realize comfortable life without blackout
Supply power stably under blackout or insufficient power situation.
2) Save electric charges
ESS utilize power generated by solar cell or wind power.
3) Stabilize electricity quality
Supply good quality power by adjusting irregular frequency.
4) Minimize fossil energy use
Reduce greenhouse gas emission and minimize environmental destruction like global warming, etc.
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