Battery chemistry comparison
The battery chemistry you choose changes how big a bank you need for the same load. Compare usable depth of discharge, efficiency, cycle life and temperature sensitivity.
| Chemistry | Usable DoD | Round-trip | Cycle life | Temp sensitivity |
|---|---|---|---|---|
| LiFePO4 | 80% | 95–98% | 3,000–6,000 | Low |
| AGM | 50% | ~85% | 600–1,000 | Medium |
| Gel | 50% | ~85% | 500–1,000 | Medium |
| Flooded lead-acid | 50% | ~80% | ~1,200 | High |
| Li-ion (NMC) | 85% | ~95% | 1,000–2,000 | Low |
What these numbers mean
Usable depth of discharge (DoD) is how much of the rated capacity you can actually draw before recharging without shortening battery life — a 100Ah lead-acid battery with 50% usable DoD reliably delivers about 50Ah, while a 100Ah LiFePO4 battery at 80% delivers about 80Ah, which is a big part of why chemistry changes how large a bank you need for the same load. Round-trip efficiency is the share of energy you get back out relative to what you put in; a lower figure means a larger solar array to cover the same daily use. Cycle life is roughly the number of charge-discharge cycles before capacity fades to about 80% of new, and temperature sensitivity describes how much cold weather derates usable capacity and, for some chemistries, restricts charging outright.
Which chemistry should you pick?
LiFePO4 is the default choice for most new off-grid and backup builds — highest usable DoD, longest cycle life, and the least temperature sensitivity, at a higher upfront cost per Ah. AGM and gel suit smaller, maintenance-free lead-acid systems or budget builds where the shorter cycle life is acceptable. Flooded lead-acid remains the cheapest per Ah but needs ventilation and periodic watering, and its high temperature sensitivity makes it a poor fit for hot climates. Li-ion (NMC) shows up mostly in repurposed EV or laptop cells rather than dedicated solar products, and needs a BMS every bit as much as LiFePO4.
Values are typical manufacturer datasheet ranges; see the methodology & sources.