Apart from the fact that batteries store energy for use at night or during inclement weather, they are also a key cost factor for stand-alone PV systems. Table 5.1 lists the key technical characteristics of PV installation batteries.
Batteries account for around 10 to 40% of the capital investment and as much as 30 to 60% of the operating costs of a PV installation, owing to the need to replace the batteries periodically. Unlike solar cells, battery costs are unlikely to decrease appreciably at any time in the foreseeable future. Lead batteries that are suitable for PV systems now cost (depending on quality) anywhere from €130 to €530 per kWh (storable energy calculated using K100).