Buy raw LFP cells for $70–$85/kWh

Home batteries are getting weirdly cheap at the cell level. Not cheap as in “Powerwall on sale” cheap — cheap as in the underlying LFP storage itself is now flirting with commodity pricing. That is the real story here. The surprise is not that a DIY battery can cost less than a branded home battery. It’s how much less. ### What exactly got cheap? The thing getting cheap is the storage core — lithium iron phosphate, or LFP, cells. BloombergNEF’s 2025 battery survey put average stationary-storage battery packs at $70/kWh, after a huge one-year drop driven by manufacturing overcapacity and brutal competition. That is pack pricing, not a polished consumer product, but it lines up with the idea that raw LFP cells for DIY systems can land in roughly the $70-$85/kWh range. ### Why does that matter? Because most people still think batteries are expensive in the same way they were a few years ago. Turns out the chemistry is not the expensive part anymore. At least not by itself. If the raw storage is around $70-$85/kWh, then a 14 kWh class battery contains well under $1,500 of core cell value before you add everything else. That changes how you should think about retail battery pricing. (about.bnef.com) ### So why is a Powerwall still so expensive? Because a Powerwall is not a pile of cells in a box. It is a finished electrical product with an integrated inverter, control electronics, thermal management, software, installation workflow, utility interconnection support, and a warranty. Tesla’s own materials show Powerwall 3 stores 13.5 kWh and delivers up to 11.5 kW AC continuous power, which is a lot more than “backup battery” marketing fluff — it is sized to run serious household loads. (about.bnef.com) ### What does the installed math look like? Using the common installed range now floating around the market — about $12,000 to $16,000 for one Powerwall 3 system — you end up at roughly $890 to $1,185 per kWh on a 13.5 kWh unit. That means the all-in consumer price can be more than 10 times the raw storage cost. The exact number moves with labor, permitting, panel work, and backup hardware, but the shape of the gap is real. (energylibrary.tesla.com) ### Is that markup just corporate greed? Not really — or at least not mostly. The expensive layers are the ones DIY buyers tend to mentally wave away. You need a battery management system, busbars, fusing, enclosure, compression, inverter or hybrid inverter compatibility, disconnects, code-compliant wiring, permits, inspections, and someone who will answer the phone if the system dies in year 7. Those are not cosmetic extras. They are the difference between “cells store energy” and “house runs safely.” (exspenditure.com) ### Why is LFP the chemistry doing this? LFP is cheaper and more stable than nickel-heavy chemistries, and the market has been flooded with manufacturing capacity built for EVs and storage. BloombergNEF tied the latest declines to overcapacity, competition, and the continued shift toward lower-cost LFP. Basically, too many factories chased too much volume, and home storage is now benefiting from the spillover. (tesla.com) ### Does that mean everyone should build DIY batteries? No — the catch is that cheap cells do not automatically make a cheap safe system. DIY makes sense for technically confident users who understand electrical protection, balancing, enclosure design, and local code. For everyone else, the premium is buying a finished appliance plus accountability. That premium still looks huge, but it is not imaginary. (about.bnef.com) ### What’s the real takeaway? The battery business is splitting in two. Storage hardware is getting cheap fast. Installed home energy systems are not. So the question is no longer “why are batteries expensive?” It is “which layers are you paying for” — raw energy storage, or the whole machine around it. (tesla.com)