Solar Power System Major Components

Batteries

In stand-alone photovoltaic systems, the electrical energy produced by the PV array can not always be used when it is produced. Because the demand for energy does not always coincide with its production, electrical storage batteries are commonly used in PV systems. The primary functions of a storage battery in a PV system are to:

  • Energy Storage Capacity and Autonomy: to store electrical energy when it is produced by the PV array and to supply energy to electrical loads as needed or on demand.
  • Voltage and Current Stabilization: to supply power to electrical loads at stable voltages and currents, by suppressing or 'smoothing out' transients that may occur in PV systems.
  • Supply Surge Currents: to supply surge or high peak operating currents to electrical loads

All stand-alone solar electric systems require battery storage. Solar panels charge the batteries during daylight hours and the batteries supply the power when it is needed, often at night and during cloudy weather.

The two most common types of rechargeable batteries in use are lead- acid and alkaline. Lead acid batteries have plates made of lead, mixed with other materials, submerged in a sulfuric acid solution. Alkaline batteries can be either nickel-cadmium or nickel-iron batteries. They have plates made of nickel submerged in a solution of potassium hydroxide.

Many types and classifications of batteries are manufactured today, each with specific design and performance characteristics suited for particular applications. Each battery type or design has its individual strengths and weaknesses. In PV systems, lead-acid batteries are most common due to their wide availability in many sizes, low cost and well understood performance characteristics. In a few critical, low temperature applications nickel-cadmium cells are used, but their high initial cost limits their use in most PV systems.

OSS represents Exide Technologies USA in Oman. Exide Technologies, with operations in 89 countries, is one of the world's largest producers and recyclers of lead-acid batteries.