If you've ever tried to buy a portable power station, you know the problem: every brand claims to be the best, the spec sheets are a wall of numbers, and the forums are full of confident but contradictory advice. "What size do I actually need?" is the most-asked question and the least-clearly-answered.
So I did the boring thing. I built a structured database of 102 portable power stations from 24 brands — capacity, output, chemistry, cycle life, solar input, weight, price — and started running the numbers. A few findings were genuinely surprising.
1. Prices quietly collapsed
The median portable power station now sits at $0.61 per watt-hour. The cheapest in the dataset is $0.39/Wh (the GRECELL T1000). A few years ago, ~$1/Wh was normal and anything under $0.70 felt like a deal.
The practical takeaway: if you're paying much more than ~$0.70/Wh in 2026, you're mostly paying a brand premium. That premium sometimes buys you a better app, ecosystem, or support — but it's worth knowing you're paying it.
2. LiFePO4 basically won
94% of the models I track now use LiFePO4 (lithium iron phosphate) instead of the older lithium-ion (NMC) chemistry. This matters more than any marketing bullet point:
- LiFePO4: ~3,000–4,000+ charge cycles
- Older Li-ion (NMC): ~500 cycles
At daily use — say you cycle it every day in a van or for backup — that's roughly 8 years vs 18 months before the battery is meaningfully degraded. If a listing still uses NMC to hit a lower price, that "deal" can cost you far more over its life.
3. The fridge myth costs people hundreds of dollars
This is the single most common sizing mistake. People size a giant, expensive battery to run a fridge because they do the math like this:
Fridge nameplate (150W) × 24 hours = 3,600 Wh/day
But a fridge's compressor only runs about 40% of the time. Its real average draw is closer to 60W, so:
150W × 40% × 24h ≈ 1,440 Wh/day
In runtime terms: a 1,000Wh power station runs a full-size fridge for about 14 hours, not the ~6 hours the nameplate math implies. Sizing on the nameplate number pushes people into a battery twice as big — and twice as expensive — as they need.
The same logic applies to anything with a compressor or thermostat: fridges, coolers, some medical devices.
4. Small devices are cheaper to run than you think
A basic CPAP machine (no heated humidifier) sips about 40W, so a modest 500Wh station gives you a full night. Flip on the heated humidifier and the draw roughly doubles — now you want 750Wh+ for the same night. Knowing which features double your power draw is worth more than buying a bigger battery.
How to size your own system (the honest formula)
You don't need a huge battery; you need the right one. Here's the math the calculator on my site automates:
-
Daily energy: add up each device's
watts × hours per day(remember the ~40% duty cycle for fridges/coolers). -
Battery size:
daily Wh × backup days ÷ 0.85(LiFePO4 gives you ~85% usable after real-world losses). -
Solar to recharge in a day:
daily Wh ÷ peak sun hours ÷ 0.75(the 0.75 accounts for wiring, controller, and temperature losses). - Inverter: add the running watts of everything you'd run at once, then add ~25% headroom for startup surge.
If you want it done automatically from an appliance list, I built a free calculator here: https://sunsee.cc/calculator
Methodology & the full data
Everything above comes from a spec database I maintain. To keep product comparisons honest, I score each unit 0–100 across six weighted dimensions — value ($/Wh), cycle life, power density, charge speed, solar capability, and output — with the formula published openly (no pay-to-play):
- Full data study, with per-brand $/Wh and price-by-year tables: https://sunsee.cc/data
- Scoring methodology: https://sunsee.cc/score
The data is free to cite (CC-BY) — just credit the source.
How it's built (for the devs)
Under the hood this is a static site: Astro + React + Tailwind on Cloudflare Pages, $0/month hosting. The interesting bet is on distribution: instead of only chasing Google rankings, everything is exposed as a free JSON API + an MCP discovery endpoint + an llms.txt, so AI assistants can query products, run the sizing calculator, and fetch runtime data directly — with attribution and affiliate links included.
The theory: a growing share of "which power station should I buy?" questions will be answered by an assistant, not a search box. So the goal is to be the data source those assistants cite, not just another blog fighting for page one.
- API:
https://sunsee.cc/api/products.json - Discovery:
https://sunsee.cc/api/mcp.json
If you've measured referral traffic from AI assistants — or have opinions on backlinks vs classic SEO for a data/tool site — I'd love to hear it in the comments.
Data from SunSee (https://sunsee.cc), CC-BY-4.0. Prices are MSRP and may vary by retailer.
Top comments (7)
Hey, quick question about LiFePO4 and cold weather – I saw you mention that 94% of power stations now use LiFePO4, but I've heard it doesn't perform as well in freezing temps. How much does the cold actually affect them? Like, I've read that efficiency can drop 20-30% or more below freezing – is that accurate?
Also, does your calculator on SunSee have an option to account for temperature? If I'm using one in a van during winter, should I be sizing it bigger to compensate for the cold, or is it not that big of a deal?
Great question — cold weather is the thing people underestimate with
LiFePO4. It helps to separate two very different effects:
Discharging in the cold: LiFePO4 will happily run below freezing, but
usable capacity drops. The 20–30% figure is closer to what you see at deep
cold (around -10 to -20°C). Right around freezing it's usually more like
~10–15%. So the efficiency hit is real, but often overstated for
mildly-below-freezing temps.
Charging in the cold — this is the one that actually bites: you should
NOT charge LiFePO4 below 0°C / 32°F. Doing so causes lithium plating and
permanent capacity loss. Most decent power stations have a BMS that blocks
charging below freezing, and some have built-in self-heating. So the real
winter-van gotcha usually isn't "my battery got smaller," it's "my solar
won't charge it on a freezing morning because the BMS locked charging until
it warms up."
Practical van-in-winter advice:
On the calculator: honestly, no — it doesn't have a temperature input yet.
It accounts for depth-of-discharge, ~25% system losses, surge, and regional
sun hours, but not thermal derating. For winter use I'd just add that
~10–20% manually on top of the result. It's a fair gap though — a "cold
climate" toggle is a genuinely good idea, adding it to my list. Appreciate
the nudge.
TL;DR: below freezing plan for ~10–15% less usable capacity (more at deep
cold), size ~10–20% up, and the bigger issue is protecting charging — keep
it warm enough to charge safely.
Update: shipped this across the board — the main calculator and all the
scenario calculators (RV, emergency backup, etc.) now have a cold-climate
temperature setting that sizes the battery up and flags the sub-zero charging
caveat. The RV one is probably most relevant to your winter-van question.
Thanks again for the nudge.
I was particularly intrigued by the finding that 94% of the models you tracked now use LiFePO4 chemistry, which significantly outlasts the older lithium-ion (NMC) chemistry in terms of charge cycles. The implications of this for daily use, such as in a van or for backup, are substantial, with LiFePO4 lasting roughly 8 years versus 18 months for NMC. This highlights the importance of considering the long-term costs and benefits when selecting a portable power station, rather than just focusing on the initial price. Do you think the industry will continue to shift towards LiFePO4, or are there potential drawbacks or trade-offs that could lead to a resurgence of other chemistries?
You've nailed the core insight — total cost of ownership, not sticker price,
is where LFP wins for anything you cycle regularly.
On where it goes from here: I'd bet LFP keeps dominating portable and
stationary power for the next several years, and NMC doesn't really "come
back" in this category. Three forces lock it in: cost (no cobalt/nickel —
which is exactly why $/Wh has collapsed), cycle life, and safety (LFP's
thermal-runaway resistance matters a lot for something sitting in your van
or living room).
Where other chemistries still hang on is weight. LFP's one genuine trade-off
is lower energy density — heavier and bulkier per Wh. So ultra-light,
grab-and-go units (small camping/backpacking power banks) sometimes still
use NMC/Li-ion to shave weight. Anything that mostly sits still, LFP wins
easily.
The chemistry I'd actually watch isn't a comeback — it's a newcomer:
sodium-ion. It's cheaper (no lithium at all), inherently safer, and — tying
into the cold-weather question someone else asked in these comments — it
performs noticeably better in freezing temps, which is LFP's weak spot. Its
energy density is still below LFP today, so it'll likely take the budget and
cold-climate segments first rather than replace LFP outright. CATL and
others are already shipping sodium-ion cells. If anything dethrones LFP at
the low end, my money's on that — not a return to NMC.
So my read: LFP dominance continues, NMC keeps only the weight-critical
niche, and sodium-ion is the wildcard — ironically because it fixes the
exact cold-weather weakness LFP has.
Great work, Hardy! I really like the direction of making structured product data available through APIs and MCP endpoints — especially with AI assistants increasingly becoming the interface for discovery and decision-making.
Projects like SunSee have a lot of interesting possibilities around AI-powered recommendations, data pipelines, agent integrations, and smarter user experiences. I’d love to collaborate if you ever need support extending the platform, building new features, or exploring AI integrations.
I focus on delivering high-quality results with fast turnaround and flexible cost options, especially for indie builders and early-stage products. Happy to contribute ideas, help with implementation, or work together on something valuable. 🚀
Thanks, Luis — really appreciate that! Right now SunSee is a solo, bootstrapped project and I'm keeping everything hands-on while I figure out what actually resonates with users, so I'm not looking to bring anyone on just yet.
That said, always happy to trade ideas — the "AI as the discovery layer" bet is exactly what I'm building toward. If you've got a take on how to actually measure referral traffic from AI assistants (ChatGPT/Perplexity/etc.), that still feels like a black box to me and I'd genuinely love input.
Either way, glad the API/MCP direction resonated — I'll keep sharing how it plays out. 🙌