12 Solar PV Systems
311
Table 12.1 Comparison of battery characteristics [4]
Type of
batteries
Cycle life (h)
75%
discharge
rate
Cycle life (h)
30%
discharge
rate
Specific
weight
(Wh/kg)
Price/kWh
C20 (e)
Cost
(e/kWh)
30%
discharge
Lead-acid
car battery
Forbidden
800
40
300
1
Lead-acid
heavy plate
battery
200
800
40
200
0.5–2
Lead-acid
OPzS
battery a
1000
2800
36
470
0.15–0.4
Lead-acid
bloc battery
1300
4500
16
570
0.18–0.6
Li-ion b
5 years
5 years
60
1000
1
a OPzS stands for stationary tubular plate battery (Types OPzS)
b Li-ion battery with a “battery management system (BMS)”, an electronic system that controls
the items of a battery pack)
Increasingly popular are off-grid installations with DC/AC inverters. For larger
applications, e.g. farmhouses and micro-grids, hybrid installations combining PV
with other sources of electricity (such as diesel-, wind-, and hydroelectric-generators)
are being introduced (Figs. 12.4 and 12.5).
Fig. 12.4 Simplified electric block diagram of SAC (Swiss Alpine Club) Monte Rosa with DC/AC
inverters [5]