IEEE Electrification Magazine - September 2015 - 17

offer continuous power to critical loads and is mainly used to
provide backup to computer systems. Continuous support
gives us the peace of mind of uninterrupted operation
against the nuisance interruptions that may come up or, in
the case of a serious disruption, ample time to properly close
and shut down the operation of critical loads.

3.50
3.00

Emergency Backup and Grid Independence
The concept of energy backup is not new to many of us. The
ubiquitous presence of uninterruptible power supply systems
in residential and commercial applications is very common
in our day-to-day lives. The purpose of these systems is to

Li-ion

2.00
1.50
1.00
0.50

Cost Savings

0.00

0-3 kWh
3-10 kWh
Source: EuPD Research 2014

10-20 kWh

Mean

US$/Wh

Figure 3. A price comparison between lead-acid and Li-ion cells for
the fourth quarter of 2014 for three storage capacity categories.

3.00
2.50
2.00
1.50
1.00 Sonnenbatterie
0.50
0
2012

2013
EuPD Low Range
EuPD High Range

Tesla
2014
Year

2015

2016

EuPD Average
Linear (EuPD Average)

Figure 4. The present and forecast price of Li-ion energy storage.

2.00

System
Battery Pack
Accessories

1.60
US$/Wh

In terms of the economics of power generation and the
consumption of energy, batteries can offer the right support to make business sense. In some markets, traditional
means of generation can be considerably more expensive
than the use of PVs or other renewables, and, with the
complement of a solid energy-storage platform, you can
normalize available power throughout the day. This makes
the combination, for example, of PV and battery storage, a
compelling alternative in remote and hard-to-reach areas.
The topic of distributed generation (DG), not only for
feeding in but also for self-consumption, has become more
relevant as the concept of net metering is no longer being
used as the default price model for feed-in tariffs. Batteries
can offer that level of parity when the feed-in rates and the
consumption rates are no longer equal.
In other instances, you can find opportunities where the
utility companies place further regulations on DG that
demand more stable generation of power. In the case of
PVs, this is usually specified by requiring PV plants to overdimension the number of solar panels in relationship to the
power conversion (inverter) components by factors up to
50% higher than nominal. This burden comes at an
increase in the cost of developing these PV plants at the
expense of losing the production of that excess power. Batteries can offer a way to store that excess power when it is
not desired for feed-in and feed at a later time when the
maximum generation limit is not met by the PV plant.
We have also seen that as solar becomes more prevalent
and mature, like in Germany, these kinds of applications are
demanding the right technology to allow for better use of PVs
and wind while maintaining a sustainable and stable grid.

Lead-Acid

2.50
US$/wh

The advances in battery technology, especially in the last
two decades, combined with unprecedented reduction in
production cost in the last five years have created the right
conditions for the deployment of mature battery storage
technologies. Figure 4 presents the projected evolution of
the price of energy storage. Although the estimates are
largely conservative, the actual price of the Sonnenbatterie
storage system is already under US$1/Wh, and Tesla has
announced a system of batteries for 2016 release that will
cost under US$0.5/Wh (Powerwall; see Hoener, 2015).
The price distribution among the battery system and additional components is shown in Figure 5. In addition to the batteries, a system needs a bidirectional inverter and/or dc-dc
converters, enclosure, connections, and control fixture. In the
near future, the optimization of the economy of scale of battery storage will be conducive to an aggressive reduction in
price similar to the experience in PVs in the last decade.

1.20
0.80
0.40
0
2012

2013

2014
Year

2015

2016

Figure 5. The price distribution among the battery and additional
equipment.

IEEE Electrific ation Magazine / S EP T EM BE R 2 0 1 5

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