LiFePO4 vs Lead Acid For Solar Storage

Usable capacity is not nameplate capacity

A lead-acid bank is normally held to a shallow depth of discharge to protect cycle life, so only part of the nameplate is available in practice. LiFePO4 tolerates a much deeper working range, which is why a lithium bank with a smaller nameplate can deliver more usable energy than a larger lead-acid one. Compare usable kWh, not rated kWh, when the two are quoted against each other.

Cycle life decides the replacement interval

Cycle life is the figure that turns a purchase price into a cost per kWh cycled. Our rack batteries state their cycle life at a defined depth of discharge in the specification table - insist on the same qualifier from any supplier, because a cycle count quoted without a depth of discharge is not comparable.

Maintenance, ventilation and siting

Flooded lead-acid needs electrolyte maintenance, equalisation charging and a ventilated space. LiFePO4 needs none of those, which removes a room, a ventilation system and a recurring maintenance task from the project scope.

Where lead-acid still makes sense

Short-duty standby applications with very few cycles, where the low purchase price is not eroded by replacement, remain a reasonable case for lead-acid. Daily cycling solar storage is not that case.