IEEE 1361:2014 pdf free download – IEEE Guide for Selecting, Charging,Testing, and Evaluating Lead-Acid Batteries Used in Stand-Alone Photovoltaic (PV) Systems
5. Lead-acid battery selection and use
lt is important to understand the advantages and limitations of the different lead-acid battery designsavailable and their performance characteristics. Battery performance is highly dependent on matching theappropriate battery design to the battery application.Lead-acid batteries are designed for engine starting,lighting，and ignition(SLI), deep-cyclc(motive power)，stationary float service(uninterruptable powersupplies or UPS),and cnergy’storage systems.Usually the deep-cycle batterices provide the bestperformance in PV systems because they have a high cycle-life and are more resistant to the deleteriouseffects of deficit-charge cycling (see Annex A).
5.1 Battery characteristics
There are a number of basic battery characteristics that can have a significant impact on PV systemperformance. Among the more important characteristics are temperature effects，recharge efficiency,sulfation, stratification, and charge voltage.Annex B contains a brief description of battery characteristicsand possible PV system design solutions for optimum battery health，e.g.，temperatures affect batteryoperation and cold temperatures can be as concerning as hot, and in very cold conditions a battery mayaccept little to no charge despite brilliant sunshine.
5.2 Selection criteria
The selection of batteries for a stand-alone PV system is typically a matter of balancing many separateissues. There are many variations of battery type, and this selection will affect the initial cost, which willinclude installation costs and building modifications (such as any ventilation required). The batterycapacity will also affect initial cost, but just as importantly，the life of the battery and its associatedreplacement costs. In all cases, it is desired to maximize the battery life to minimize the overall cost of thePv system.
5.2.1 Battery types
Although local availability may ultimately influence the final decision, there are many types of batteriesthat can be considered for a stand-alone PV system. Flooded, deep cycle batteries, such as used in golf cartsand forklifts,are often a good choice. They are made for the repeated,deep cycling often seen in PVsystems.As a flooded design, they will necessitate proper ventilation to prevent hydrogen accumulationand will also require planned electrolyte maintenance and periodic access to the batteries. Variations in thelead alloys used in these batteries will affect the maintenance levels，service lifc，and chargingcharacteristics，which may provide one variation with an overall advantage,depending on the specificcharacteristics of the site. This will have to be determined from a careful analysis of the PV system underconsideration. Automobile starting batteries, often known as SLl batteries, may have the lowest initial cost,but are not made for deep cycling and often require frequent replacements, thus having a higher overall costof ownership.
5.3 PV system parameters
PV system parameters need to be defined with the battery in mind. Small system modifications can have adramatic impact on battery performance. Ilt is important to clearly define battery charging requirements andmeet those charging requirements with proper charge control voltage and array sizing (see Annex C).Manyof the parameters selected are dependent on the system load profile,sitc weather conditions，systemhardware， and battery requirements.Because of the high life-cycle costs associated with the battery, thecharging requirements of the battery should be identified first, then the PV system should be designed toprovide those battery charging requirements. For example, if a battery needs to be charged to 2.35 V percell and only discharged to 1.95 v per cell, then a PV charge controller that charges to the appropriateregulation voltage and limits discharge to the specified LVD should be used. The same process can also beused to evaluate a range of charge-to-load ratios and charge rates. For example, if the PV battery needsmore time at regulation voltage and/or requires a weekly finish-charge, then a larger PV array-to-load ratiois required to provide the longer finish-charge time necessary to maintain a higher state-of-charge.