Solar Systems, are built to last longer and are rugged enough to be used in any weather condition.
Usually, Solar Photovoltaic Systems require battery subsystems to store the reserve electrical energy for times when there is zero insulation. These installations require battery subsystems with minimum maintenance due to the high costs associated with transporting personnel and providing parts to various sites.
At times like this, the selection of a proper battery for Solar Photovoltaic Systems requires a complete analysis of the battery discharge requirements. The kilowatt-hours of energy stored in the battery depending upon the load requirements, the number of days of storage, the insulation patterns in the geographical area of the installation and the solar array output. Other factors taken into consideration while sizing the battery are operating temperature variations, environmental temperature extremes and weekly/daily usage, the voltage regulator design, and the efficiency of the inverter. Also, the energy required to charge a battery will be the sum of the previous discharge energy output and the energy expended as work and excess heat during the recharge. Longer charge times and lower charge currents tend to increase charge efficiency.
In lead-acid batteries, turn around energy efficiency can approach 85 percent. Shorter charge times and higher charge currents will sacrifice energy efficiency and battery life. Charge time and power available from the solar array must therefore be considered in selecting the battery type and size.
Battery operating life in the solar PV system is a function of the operating temperature, the duty cycle, the depth of discharge, the charge control and the cell design. Significantly higher average operating temperature decreases life, and the number of available charge-discharge cycles decreases with increasing depth of discharge.