How long can solar batteries usually last?

You can anticipate a domestic battery in a mild environment with regular use to endure for 10 years. Solar batteries, on the other hand, subjected to elevated temperatures and operating intensely daily, may have an effective lifespan of about 5 years.

Defining the End of Life for a Solar Battery

Off-Grid

In off-grid solar setups, the battery is the primary power source, and 'End of Life' (EOL) occurs when its capacity degrades to the point where it can't support the load, leading to power shutdown. This concept is more distinct compared to grid-tied systems.

Grid-Tied

For grid-connected systems with backup features, the definition of discerning EOL isn't as uncomplicated. Even if the battery's capacity has considerably diminished, it could still serve as a backup, holding value as long as it meets the crucial power requirements during outages.

In cases where the crucial role of the grid-connected battery system is to manage peak demand and diminish electrical costs, defining the precise EOL can pose as a greater challenge. Unlike an isolated system, the grid seamlessly takes over, ensuring power supply as and when needed.

The Period of Warranty from the Manufacturer

When demonstrating the cost-effectiveness of solar cells, the manufacturer's warranty period generally concludes, typically after 10 years. Surpassing this warranty period is often regarded as the end of its service life.

Nevertheless, the actual lifespan could be more extended with proper care, as manufacturers generally construct their warranties with a certain level of caution in mind. The SoH (State of Health) defined under the guarantee aims to secure a decent grade of battery efficiency, provided it's functioned within the specifications set by the manufacturer.

What are the indications of a deteriorating solar battery?

The signs of a degraded solar battery can differ based on its chemical composition, structure, and mode of utilization. Nevertheless, certain universal indications could signal a battery reaching its operational limits within a domestic solar energy storage setup. In the past, I've created an in-depth piece on this very topic.

Extreme Temperature Conditions

Akin to us, a battery functions more effectively when it is not exposed to exceedingly high or low temperatures. Optimum performance usually occurs within a range of approximately 20 to 25ºC. Subjecting a battery to temperatures exceeding this recommended limit accelerates the internal chemical reactions, leading to a hastened degradation of its components. Elevated temperatures also result in a rapid reduction of the battery's capacity, thereby shortening its usable life span.Regular exposure to severe cold can similarly diminish a battery's efficacy and contribute to long-term degradation of its capacity and overall lifespan. Intense cold can even cause mechanical strain on the battery, possibly affecting its structural solidity.

Number Of Charge/Discharge Cycles

It's not by coincidence that many manufacturers' warranties are correlated with the number of charge/discharge cycles in a solar battery's lifespan. Each cycle contributes to gradual wear and chemical alterations, leading to a reduction in capacity over time.

The energy storage of lead-acid is more influenced by the number of cycles than lithium-ion batteries. Regular cycling, particularly deep discharges, can lead to the accumulation of sulphate on the battery plates, which reduces capacity and shortens its lifespan.On the other hand, lithium-ion batteries can withstand a higher number of cycles and deeper discharges. Reducing the frequency of cycles through efficient energy management can help prolong its lifespan, no matter the chemistry.

Depth Of Discharge (DoD) And State Of Charge (SOC)

The Depth of Discharge (DoD) refers to the proportion of a battery's total capacity that has been depleted. The larger the DoD, the more it significantly influences the battery's lifespan due to the increased strain on its chemical composition. Discharges that aren't as deep, where the battery isn't entirely drained, result in slower capacity reduction and longer overall battery life.

Manufacturers commonly include DoD conditions in their battery warranties. For instance, a lithium-ion battery manufacturer might specify that the battery shouldn't consistently be discharged below a certain percentage of its capacity (such as 80% DoD) to uphold the warranty. Surpassing these recommended DoD percentage levels can lead to quicker degradation not accounted for in some warranties.

Meanwhile, the State of Charge (SoC) shows the present charge level of a battery as a fraction of its maximum capacity. Li-ion battery makers may suggest avoiding regularly charging it to 100% SoC. Even though these SoC restrictions may not be as heavily emphasized as DoD limits, maintaining appropriate SoC levels can assist in keeping the solar battery's capacity and lifespan intact.

Examining Duration and Knowledge to Extend Battery Longevity

The Depth of Discharge (DoD) refers to the proportion of a battery's total capacity that has been depleted. The larger the DoD, the more it significantly influences the battery's lifespan due to the increased strain on its chemical composition. Discharges that aren't as deep, where the battery isn't entirely drained, result in slower capacity reduction and longer overall battery life.

SUNESS 95%DOD 15KW Lifepo4 Battery