IEEE Electrification Magazine - September 2015 - 24

Cost <2.5 kW

7,000

2.5-4.5

4.5-6.5

6.5-9.5

9.5-14

14-25

25+

AUD

5,250

3,500

1,750

0

1 2 3 4 5 6 7 8 9 1011121 2 3 4 5 6 7 8 9 1011121 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5
2010
2011
2012
2013
2014
Year

Figure 1. PV system cost per kilowatt since 2010 in Australia by installation size.

turning off certain devices at specified times or situations,
and controlling various generation sources with different
responses when available. However, one of the most effective solutions is to deploy storage to address this problem.

Types, Use, and Optimization of
Storage in Residential Applications
Types and Use
Most residential storage systems are now lithium-based
chemical batteries, with a multitude of suppliers from the
United States, China, Korea, Japan, and Europe offering
multiple off-the-shelf products. The typical capacity of
these batteries is between 5 and 15 kWh. These systems
typically include a hybrid grid-tied inverter (2-5 kW) and a

230

3,950

210

2,150

150

1,550

130

950

110

350

90

-250

M

ar
c
M h2
ar 00
c
M h2 5
ar 0
c 06
M h2
ar 00
c
7
M h2
ar 00
c
8
M h2
ar 00
c
9
M h2
ar 01
ch 0
M
ar 201
c
1
M h2
ar 01
ch 2
M
ar 201
c
3
M h2
ar 01
ch 4
20
15

Index

2,750

170

Megawatts

3,350

190

Electricity Price Index

PV Output (15-Month Shift)

Figure 2. The average Australian retail electricity price index (base =
March 2005) (left-hand side) and Australian PV output (MW), shifted
back 15 months (right-hand side).

24

I E E E E l e c t r i f i cati o n M agaz ine / SEPTEMBER 2015

solar PV maximum power point tracking controller and
battery charger.
In Australian residential areas, the average daily household consumption is 19 kWh, so these systems can only
store between 25 and 80% of the average daily energy
required. However, as already discussed, one of the most
valuable roles for storage is to reduce or eliminate the need
for grid-sourced energy in the peak period. Depending on the
individual household load profile, the available energy from
these batteries may be sufficient to satisfy the load during
the peak period, which is typically from 2 to 8 p.m.
Currently, most household storage is operated within a
simple schedule designed to charge the BESS from the grid
during off-peak hours and to provide the load with either PV
generation or combined PV generation and storage during
the day. Excess PV power, if available, can be exported (if the
local utility allows it), but only after the battery is fully
charged (Figure 3). During the evening and night, the BESS is
discharged to reduce or eliminate any import during peak
tariff periods.

Optimization
There is a great deal of scope to optimize household electricity usage and generation via the combination of PVs,
storage, demand management, and grid supply. Essentially,
the addition of storage into the mix allows intelligent load
and generation shifting so that homeowners can reduce
their electricity bills by minimizing their peak and shoulder-period consumption.
However, to more fully utilize the storage resource, it is
necessary to anticipate the next day's PV output and expected load (Figure 4). This is important because the battery state
of charge (SoC) must be in the correct band for the daily
requirement. For example, if the upcoming day is likely to be



Table of Contents for the Digital Edition of IEEE Electrification Magazine - September 2015

IEEE Electrification Magazine - September 2015 - Cover1
IEEE Electrification Magazine - September 2015 - Cover2
IEEE Electrification Magazine - September 2015 - 1
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IEEE Electrification Magazine - September 2015 - Cover3
IEEE Electrification Magazine - September 2015 - Cover4
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http://www.nxtbook.com/nxtbooks/pes/electrification_march2019
http://www.nxtbook.com/nxtbooks/pes/electrification_december2018
http://www.nxtbook.com/nxtbooks/pes/electrification_september2018
http://www.nxtbook.com/nxtbooks/pes/electrification_june2018
http://www.nxtbook.com/nxtbooks/pes/electrification_december2017
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http://www.nxtbook.com/nxtbooks/pes/electrification_march2018
http://www.nxtbook.com/nxtbooks/pes/electrification_june2017
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http://www.nxtbook.com/nxtbooks/pes/electrification_march2016
http://www.nxtbook.com/nxtbooks/pes/electrification_march2015
http://www.nxtbook.com/nxtbooks/pes/electrification_june2015
http://www.nxtbook.com/nxtbooks/pes/electrification_september2015
http://www.nxtbook.com/nxtbooks/pes/electrification_march2014
http://www.nxtbook.com/nxtbooks/pes/electrification_june2014
http://www.nxtbook.com/nxtbooks/pes/electrification_september2014
http://www.nxtbook.com/nxtbooks/pes/electrification_december2014
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