IEEE Power & Energy Magazine - March/April 2015 - 52

figure 1. Annually installed PV capacity in Germany as of
July 2014 (source: www.energymap.info).

The batteries are designed to cope with PV systems whose
nominal power is 5-8 kWp, and their capacities usually vary
from 2 kWh to 12 kWh. The prices for such battery systems
still vary considerably and depend greatly on the technology
used and the capacity of each system. Most suppliers, however, currently offer their PV storage systems for €5,000-
15,000; such systems typically include a 5-kVA inverter and
a 4-kWh lithium-ion battery.
In May 2013, the German government introduced an
incentive program that financially supports investments in
residential-scale PV storage systems. In addition to a soft
loan, the program provides up to €600 per installed nominal kW of PV capacity when a battery system is installed
in parallel. The program obligates participants to limit the
active power feed-in over the household's point of common

6
5
4
3
2

2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014

1
0

Share of PV Energy on German
Electricity Consumption (%)

8
7

GWp
Share of PV Systems
on German Electricity
Consumption

2001

Installed PV Capacity (GWp)

45
40
35
30
25
20
15
10
5
0

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

Annually
Installed PV Capacity (GWp)

10
9
8
7
6
5
4
3
2
1
0

figure 2. Accumulated installed PV capacity in Germany
and the share of PV energy in total German electricity consumption, as of July 2014 (source: numbers for the installed
capacity from www.energymap.info and German net electricity consumption from https://www.bdew.de/internet.nsf/
id/DE_Energiedaten).

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at
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as
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ar
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Installed Capacity (GW)

coupling to 60% of the installed PV capacity. So far, approximately 15,000 PV storage systems have been sold since the
beginning of the investment program.
To assess the economic viability of the PV storage
option, a short case study will be presented. Accordingly,
various household consumption profiles, PV system sizes,
and battery sizes are simulated to determine the resulting
self-consumption, self-sufficiency, and grid feed-in numbers.
Figure 5 displays self-consumption and self-sufficiency for
different PV battery configurations for a sample household-
in this case, a four-person family.
Self-consumption and self-sufficiency show the PV battery system's
capability to reduce grid feed-in of
40
generation and to reduce grid supply
37.47
for local load demand. A PV self35
32.005
consumption of 100% indicates that
30
all of the locally produced PV energy
27.239
24.911
is consumed locally, and a self-suf25
21.238
ficiency of 100% indicates that no
20
electricity from the grid is consumed.
The trade-off between self-con15
12.068
sumption and self-sufficiency thus
9.24
10
7.14
becomes visible. Smaller sizing of
5.997
4.082 3.873
5
PV systems allows for increased selfconsumption but lowers the potential
0
for increased self-sufficiency.
Further analyses show how
optimal installed system sizes
change with a decreasing FIT and
Data Source: German Federal Network Agency for Electricity, Gas,
an increasing electricity price. In
Telecommunications, Post, and Railway, "Monitoring Report 2013"
the future, though, local generation via PV systems will need to be
more finely adjusted to local load
figure 3. Installed capacities of different electricity sources in Germany as of 2013.

52

ieee power & energy magazine

march/april 2015
http://www.energymap.info http://www.energymap.info https://www.bdew.de/internet.nsf/
Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - March/April 2015
