Solar PV: Concerned about lead-acid battery longevity?

Solar PV: Concerned about lead-acid battery longevity?

By Bevan Jones, Technical Director at Soltra Energy

One of the most effective ways to prolong the life of lead-acid batteries used for energy storage in solar PV applications is to install a battery monitoring/ balancing solution.

In solar PV applications the batteries are regularly cycled – charged during the hours of daylight and discharged at night – which can have a detrimental effect on their longevity. This is the result of accelerated sulfation, dendritic growth, shedding (loss of material from the plates), electrolyte loss through gassing, decomposition of the electrolyte and a host of other negative issues that regular cycling promotes.

While the typical life of a lead-acid battery is between 300 to 500 cycles, it can be reduced considerably when batteries are subjected to deep discharges on a regular basis. On the other hand, battery life can also be extended with the use of a balancing solution.

The key to battery longevity – and reduced maintenance - lies in a thorough understanding of the status of individual batteries in a multi-battery pack in terms of their duty cycles and load factors.

While costly lithium-ion batteries are increasingly specified for solar PV and other applications where regular cycling is mandated, users should not be dissuaded from installing cheaper, lead-acid batteries when appropriate.

Today, ‘smart’ battery monitoring/ management technology is able to optimise individual battery performance on a 24x7 basis. A dedicated, computerised battery balancing harness is incorporated that automatically monitors a wide range of parameters associated with individual batteries in the pack.

Data streams containing information critical to the well-being of individual batteries, including temperature, state of charge and depth of discharge, are measured on a continual basis, while a tally of the number of discharge/ charge cycles is accurately recorded.

Battery performance can thus be balanced and equalised and should an individual battery’s operating parameters not meet design specifications or fail for any reason it is flagged for replacement, thus ensuring the integrity of the pack.

The technology featured in this modern battery management system not only distributes and balances the battery load as well as discharge and charge regimes across all batteries in the pack, it also takes steps to ensure that no battery is compromised through over-cycling or a malfunction of any kind.

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