How much capacity
do I actually need?
The single number that determines whether a power station works for you — calculate it before you spend anything.
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When buying a portable power station, most people focus on brand names or price. But the number that actually determines whether a station works for you is its capacity in watt-hours (Wh). This tells you how much total energy the battery can store — and directly determines how long it will run your devices.
Think of it like a gas tank. The wattage (W) is your engine size — how much power it can deliver at once. The watt-hours (Wh) is how much fuel is in the tank. You need both to be right, but capacity is where most buyers go wrong.
Most modern power stations use lithium iron phosphate (LFP) cells — safer, longer-lasting (3,000+ charge cycles), and more heat-tolerant than older lithium-ion packs. LFP is now the standard for quality stations.
One more thing: rated capacity and usable capacity aren't always the same. Some manufacturers reserve 10–20% to protect battery longevity. Always check the usable Wh in the spec sheet, not just the headline number on the box.
The simple formula: Device wattage × hours of use = Wh needed per day. Add 25% as a buffer for efficiency losses and degradation over time. That's your minimum station capacity.
The expandability rule: If two stations have similar specs but one is expandable, choose the expandable one. Your needs will grow — it's only a matter of when.
Use this as a quick reference before diving into the calculator. Each tier represents a meaningful jump in capability.
Good for:
- Phone charging ×20+
- Laptop for a full day
- CPAP for 1 night (no humidifier)
- LED lights for 2–3 nights
- Small fan for 8–10 hours
Best for: day trips, short camping, occasional backup
Good for:
- CPAP for 2–3 nights
- Mini fridge for 10–14 hours
- Laptop + devices all weekend
- LED lights for 5+ nights
- Starlink for 12+ hours
Best for: weekend camping, short home outages
Good for:
- Full-size fridge for 14–18 hours
- CPAP for 4–6 nights
- Full van life weekend setup
- Home backup for critical circuits
- Multiple devices simultaneously
Best for: van life weekends, 24–48 hr home backup
Good for:
- Full-time van life daily use
- Multi-day home backup
- Oxygen concentrator (partial)
- Fridge + devices with solar
- Off-grid cabin setup
Best for: full-time van life, serious home backup
Battery capacity degrades over time — even with LFP chemistry, you'll lose 10–20% over several years of regular use. Your needs also tend to grow as you add devices. Buy at least 25–50% more than your current daily calculations suggest.
Also consider expandability. EcoFlow, Anker, Bluetti, and Jackery all offer stations that pair with extra battery packs later. Starting with an expandable unit means you're not locked into your day-one estimate.
Select every device you want to run. We'll calculate your daily Wh requirement and recommend the right capacity tier — and the stations that fit.
What do you need to power?
Select everything you want to run — we'll do the math.
Multiply wattage by daily hours to get your Wh need. For appliances with motors, the startup surge wattage must be within your station's peak rating.
| Appliance | Avg wattage | Startup surge | Typical daily hrs | Daily Wh |
|---|---|---|---|---|
| Smartphone charging | 5–10W | — | 1–2 hrs | 10–20Wh |
| Laptop (MacBook / PC) | 30–65W | — | 6–8 hrs | 180–520Wh |
| LED lighting (per bulb) | 8–12W | — | 4–6 hrs | 32–72Wh |
| 12V compressor fridge | 30–60W avg | 150–200W | 24 hrs | 720–1,440Wh |
| Full-size household fridge | 100–200W avg | 600–900W | 24 hrs | 2,400–4,800Wh |
| CPAP (no humidifier) | 30–50W | — | 8 hrs | 240–400Wh |
| CPAP (with humidifier) | 60–100W | — | 8 hrs | 480–800Wh |
| Oxygen concentrator | 300–600W | 600–900W | 8–24 hrs | 2,400–14,400WhRequires 3,600Wh+ station + solar recharge plan |
| Starlink internet | 40–75W | — | 8–24 hrs | 320–1,800Wh |
| 12V fan | 15–30W | — | 8–24 hrs | 120–720Wh |
| Window A/C (5,000 BTU) | 500W | 1,500–2,000W | 2–4 hrs | 1,000–2,000WhCheck station surge rating before attempting |
| Single-burner induction | 600–1,200W | — | 0.5–1 hr | 300–1,200Wh |
| Electric blanket | 50–100W | — | 8 hrs | 400–800Wh |
| Nebulizer | 50–100W | 100–150W | 0.5–1 hr | 25–100Wh |
A power station has two output ratings: continuous wattage (what it can sustain) and surge/peak wattage (what it can handle for a split second at startup). Motors, compressors, and pumps can spike to 2–3× their running wattage when they first turn on.
If your station's surge rating is lower than your appliance's startup spike, it will trip the overload protection and shut off — even if the continuous draw is well within range. Always check both numbers before buying.
12V compressor fridge
Most stations handle this easily — even budget units have 1,000W+ surge. Not a concern for camping fridges.
Full-size household fridge
Still manageable for any quality station. Verify the station's surge spec is at least 1,200W+ to be safe.
Window A/C unit (5,000 BTU)
Requires a station with 3,000W+ surge rating. Not every 2,000W station can handle this — check the spec sheet.
Well pump (1/2 HP)
Needs a heavy-duty station with 4,000W+ surge. This is F3800 or Delta Pro Ultra territory — and a conversation with an electrician.
The rule of thumb: For any appliance with a motor or compressor, find its starting wattage (not just running wattage) and make sure your station's surge/peak rating exceeds it by at least 20%. The manufacturer's spec sheet lists both numbers.
CPAP machines are manageable. Oxygen concentrators are not. If someone in your household depends on medical equipment, the stakes change the entire sizing conversation — and a standard capacity calculator won't cut it.
Not all medical devices are equal
The draw varies enormously by device type. Here's what you're actually working with — and what it means for station sizing.
CPAP (no humidifier)
30–50W continuous. Most 1,000Wh stations handle 2–3 nights comfortably.
CPAP (with humidifier)
60–100W. Humidifiers roughly double the draw. Size up to 2,000Wh for multi-night use.
Nebulizer
50–100W for 15–30 min sessions. Low total Wh but verify the station handles the startup surge.
Oxygen concentrator
300–600W continuous. A 2,000Wh station runs one for only 3–6 hours. You need 3,600Wh+ and a fast solar recharge plan.
Home ventilator
150–400W depending on type. Requires 0ms UPS switchover. The Delta Pro Ultra is the only portable station with this. Consult your medical team.
Insulin / medication fridge
30–60W continuous. Similar to a 12V camping fridge. A 1,000Wh station covers 16–30 hours.
Important: For ventilators and life-critical devices, always consult your medical provider before relying on any portable power station. A UPS function and 0ms switchover are non-negotiable for some equipment.
Running medical equipment? Our dedicated guide covers device-specific runtimes, UPS requirements, and the exact station picks for CPAP, O₂, and medication fridges.
Read: The 24-hour medical backup plan →A station is only as useful as your ability to refill it. If you're off-grid, the solar math is just as important as the capacity math. Here's everything you need to know — from panel types to positioning to daily math in New Mexico conditions.
How much solar do you need to refill your station daily?
In New Mexico you get roughly 6–7 peak sun hours per day — some of the best solar conditions in the country. A single 200W panel delivers around 1,000–1,200Wh on a good day. Two panels get you 2,000–2,400Wh.
Divide your station capacity by 6 (peak sun hours) to get the panel wattage you need for a one-day full recharge. A 2,000Wh station needs ~333W of panels — two 200W panels cover it.
Panels capture sunlight
Photovoltaic cells convert sunlight into DC electricity. Output varies by panel wattage, sun angle, temperature, and cloud cover. Real-world output is typically 70–80% of rated wattage.
MPPT controller regulates flow
Better stations use Maximum Power Point Tracking (MPPT) controllers — they continuously adjust voltage to extract maximum power. MPPT outperforms older PWM controllers by 20–30%.
Battery stores the energy
DC power charges the LFP cells. LFP accepts solar well, but most stations won't charge below 32°F (0°C) — the cells protect themselves from cold-weather damage.
Inverter converts for your devices
Your station converts stored DC to AC (or DC outputs) for devices. This conversion is ~90% efficient — factor that in when calculating usable energy.
Rigid monocrystalline
Most efficient22–24% efficiency. Best output per square foot. Ideal for fixed rooftop or ground mounts where weight doesn't matter.
Best for: permanent home or cabin installsBifacial monocrystalline
Desert advantageCaptures reflected light off the ground — adds 5–15% in high-albedo desert environments like New Mexico. Requires elevated mount.
Best for: NM ground mounts, open desertPortable folding panels
Most flexibleFoldable and lightweight for travel. Slightly lower efficiency (18–22%) but pack small. Most match directly to portable power stations.
Best for: camping, van life, overlandingFlexible / semi-flexible
Curved surfacesThin and light — great for van rooftops or boat decks. Lower efficiency (16–19%) and shorter lifespan than rigid panels.
Best for: van roof installs, curved surfacesNM desert tip: Dust accumulation on panels can reduce output by 10–25% over a few weeks. A quick wipe-down with a damp cloth every 1–2 weeks makes a meaningful difference.
Building a full solar + station setup? Our solar guide covers specific panel recommendations, cabling, and mounting options for desert conditions.
Read: Solar panel solutions guide →The best stations from across the brands at each capacity level — matched to real-world use cases. All use LFP chemistry unless noted.
Explorer 1000 Plus
Best 1,000WhThe easiest station to recommend at this tier — simple, reliable, expandable to 5kWh. Great if you want it to just work without thinking about it.
Check for current priceBuy on Amazon →Delta 2
Fastest charge 1kWhCharges 0–100% in about 80 minutes. Best choice if fast wall recharging before a storm matters most to you.
Check for current priceBuy on Amazon →AC200MAX
Best value 2,000WhBest watt-per-dollar at the 2kWh tier. Expandable with B230/B300 packs. Great for home backup and van life weekends.
Check for current priceBuy on Amazon →Delta Pro
Best 3,600WhThe go-to for serious home backup and full-time van life. UPS function, whole-home panel integration, expandable to 25kWh.
Check for current priceBuy on Amazon →