LFP vs NMC home batteries: what the chemistry actually changes

What LFP and NMC actually are

Both chemistries are lithium-ion. The difference is the cathode — the positive electrode that gives the cell most of its characteristics. LFP uses lithium iron phosphate (LiFePO₄). NMC uses lithium nickel manganese cobalt oxide (LiNi_xMn_yCo_zO₂), with several common ratios — NMC 622, NMC 811, and recently a few NMC 9 1/2 formulations pushing nickel content higher¹.

The cathode chemistry sets four downstream properties: nominal cell voltage (LFP 3.2V, NMC 3.6–3.7V), specific energy (NMC higher per kg), thermal-runaway onset temperature (LFP higher), and cycle life (LFP longer). Everything else in the cell — the anode, the electrolyte, the separator — is broadly similar between residential LFP and NMC packs in 2026.

For our Texas customer — wall-mounted residential install, ambient in the 60–130°F band most of the year⁵, expected to last 10+ years through a Williamson County climate — the cathode-driven differences land squarely in LFP's favor. That's the analysis that drove our decision to ship LFP. For an electric vehicle — where every pound costs range — NMC still wins; that's a different use case Base doesn't serve.

The four axes that actually matter for a Texas household

1. Cycle life — how many full discharges the cell can take

NREL's 2024 ATB pegs residential LFP at 4,000–6,000 cycles to 80% retained capacity². Manufacturer-rated NMC residential packs run 2,500–4,000 cycles to the same threshold. A Texas household cycling once a day on backup-only duty hits LFP's warranty boundary in 11–16 years; the same household on NMC hits it in 7–11 years. A VPP-enrolled battery (cycling 1.3–1.5×/day average across a year of TX-market participation) compresses both, but the LFP delta widens — heavy-cycle duty is where chemistry matters most.

2. Calendar aging in Texas heat

Both chemistries lose capacity over time even with no cycling — calendar aging. The rate doubles roughly every 18°F sustained ambient above 77°F (Arrhenius behavior)¹. NOAA stations across Williamson, Travis, and Dallas counties show 30+ days each summer above 95°F⁵; outdoor enclosure interiors at the battery's install location run hotter still. Both LFP and NMC derate in that environment; LFP's slope is slightly gentler. North-facing exterior placements (which Base prefers when the site allows) age more slowly than west-facing — but the chemistry advantage stacks regardless of placement.

3. Thermal-runaway risk and code conformance

LFP's thermal-runaway onset is ~270°C; NMC's is ~210°C¹. The practical implication for a Texas homeowner: LFP residential packs typically pass UL 9540A propagation tests without forced active cooling⁴; NMC residential packs typically require active thermal management (liquid or forced-air) to pass. NEC 2023 Article 706 and NFPA 855 govern which packs can be installed where in a residential structure⁸. LFP's wider safety margin means more permissive install location options. Base ground- mounts its LFP systems on the exterior wall near the meter, with active fire suppressants built into the enclosure — the full UL 1973/1741/9540/9540A stack passes the Texas/CA-driven residential rule sets cleanly.

4. Depth-of-discharge — how much of the rated capacity is usable

LFP supports 100% DoD on most modern residential packs without measurably faster degradation². NMC was historically restricted to 80–90% DoD in residential packs; manufacturers reserved the bottom 10–20% as a longevity buffer. For Base's 25 kWh single LFP system, the rated capacity is largely usable down to the BMS reserve floor; a comparable 25 kWh NMC pack would practically deliver ~22.5 kWh at the same warranty terms. The delta is real money during a long Williamson County outage.

What Base ships, and how it compares to the rest of the market

100% of new battery shipments Base installs across Round Rock, Plano, Sugar Land, and the rest of our served Oncor and CenterPoint territories in 2026 are LFP-chemistry residential systems. Most of the rest of the residential market has converged with us; for context on the alternatives, the table below maps the major LFP residential systems in 2026 plus a legacy NMC reference point.

The legacy Powerwall 2 (NMC) line is in the table because households who installed in 2019–2022 will be reading this article while still under warranty — not because Base ships it. We don't.

Cost trajectory and the cobalt question

BloombergNEF's annual lithium-ion price survey shows LFP cell prices materially below NMC for residential applications, and the gap widening — driven by LFP's cobalt-free supply chain and the Chinese cell-manufacturing buildout (CATL, BYD, EVE)⁹. Cobalt prices spiked through 2018–2022 and remain volatile; the Democratic Republic of Congo, where most cobalt is mined, is a single-point-of-failure for NMC supply chains.

For Texas households, this matters in three ways. Replacement battery prices in years 10–12 will land lower for LFP than for NMC. Tariff and trade exposure for cell imports falls more heavily on the cobalt-content chemistries. ESG concerns — cobalt's mining-conditions documentation⁹ — are real and increasingly cited by households shopping the renewable-energy side of the cluster.

None of this is a marketing claim about LFP being "cleaner". It's a structural cost and supply-chain difference that compounds over the lifetime of a Williamson County install.

When NMC still wins (and it isn't your house)

NMC's specific energy advantage — roughly 200–250 Wh/kg vs LFP's 140–170 Wh/kg¹ — is binding when the battery moves. Electric vehicles, e-bikes, drones, and aviation pay real range or payload cost for every extra kg of battery. Residential storage doesn't. Residential battery weight is fine for a ground-mounted exterior install; the same weight in a sedan would cost ~5% of EV range.

This is why NMC is not "obsolete." It's still the right chemistry for the EV in your Plano driveway. It's the wrong chemistry for the appliance against your exterior wall. The chemistry switch in residential storage is not a generation pivot — it's a use-case pivot. Both chemistries continue to ship in 2026 to the workloads they fit.

If your existing battery is NMC: don't replace it

Texas households with a 2018–2022 NMC residential battery are doing real work for real backup duty, and we tell them so when they ask. Cycling through the existing 10-year warranty and replacing at end-of-life is the right play; the chemistry change matters for a *new* purchase decision, not for retrofits. Base doesn't sell against working hardware.

Most TX NMC installs from 2019–2021 are 4–6 years into their 10-year warranty as of 2026. The structural answer is to use the battery, watch for capacity-derate behavior, and plan a replacement for ~year 9 of original install — at which point Base will be installing 2030-vintage LFP packs that will be cheaper, denser per dollar, and warrantied longer than the system they replace.

LFP's two real downsides

Honest accounting: LFP is not free of trade-offs. Two are worth naming for a Texas household making the buying decision.

Weight. LFP cells are heavier per kWh than NMC. For a wall-mounted install, that means the structure has to carry it; for ground-mounted exterior installs (the Base default for the 25 kWh and 50 kWh ground configurations), weight is irrelevant. The 20 kWh Base wall-mounted variant accounts for the wall-loading delta in its mounting hardware.

Flatter voltage curve. LFP cells discharge almost flat through the middle 70% of state-of-charge — the voltage barely moves. NMC's voltage drops more linearly, which gives the BMS a clean signal for state-of-charge estimation. Modern LFP BMS firmware handles this with coulomb counting plus periodic recalibration; older third-party LFP packs sometimes show state-of-charge "jumps" near the top or bottom of the curve. The systems Base ships handle this in firmware — not a customer-facing concern.