On this pageSpecs Carrying it, light loads, want fast turnaround Charging cameras, drones, and laptops over USB-C Family or fridge weekend camping and RV CPAP and medical overnight backup Multi-day outage, value-first essential backup Always-on UPS for networking and critical electronics

Anker SOLIX C300vsAnker 535 PowerHouse

These two share a ~$300 price but split on capability. The 535 PowerHouse delivers 1.78× the energy (512 Wh vs 288 Wh), 1.67× the output ceiling (500 W vs a measured ~255 W), and half the cost per watt-hour—at the expense of nearly double the weight, slower charging, and aging ports. The C300 counters with half the weight, a one-hour built-in recharge, dual 140 W USB-C ports, and a confirmed seamless UPS—at the cost of capacity and headroom. Same money, opposite trade. But first, internalize the shared hard wall: neither unit runs heating elements—kettles, coffee makers, hair dryers, space heaters, microwaves all trip both units cold, regardless of any surge claim. The C300’s 600 W surge rating was vetoed by bench testing (couldn’t sustain even the rated 300 W; real ceiling ~255 W, surge holds only seconds), and the 535’s 500 W ceiling shut down on a 659 W hair dryer. If your need involves hot coffee or emergency heat, both are the wrong tool; stop here and size up.

Anker SOLIX C300

$300

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Prices and availability change frequently

Anker 535 PowerHouse

$299.99‡

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Prices and availability change frequently

Spec	Anker SOLIX C300	Anker 535 PowerHouse
Capacity	288 Wh (LiFePO4)	512 Wh (LiFePO4)
Rated output	300 W	500 W
Surge	600 W rated^*	Not published
Weight	9.1 lbs	~16.5 lbs^†
AC recharge	~0.83 hr (~50 min to 80%, ~66 min full at 330 W, charger built in)	~2.5 hr to 80%^†, ~4.5–5 hr full
Solar input	100 W max (Anker 60 W/100 W panels only)	~120 W ceiling^† (real-world 60–75 W, 8 mm barrel)
AC ports	2	4
USB-C	3 (140 W / 140 W / 15 W)	1 (60 W in/out)
USB-A	1 (12 W)	3
Car port	1 (120 W)	1 (12 V/10 A)
Voltage	120 V, pure sine (scope-confirmed)	110 V (pure sine not spec-labeled; review confirms clean operation on sensitive devices)
UPS	Yes, 10 ms switchover (firmware-fixed auto-restore)	Unknown in spec^†; ~20 ms switchover measured but unreliable as continuous UPS (120 W charge cap)
Noise	25 dB (effectively silent)	Not published; review says quiet/unnoticeable^†
Warranty	5 yr	5 yr
Price	$300	$299.99^‡
Cost per Wh	$1.04	$0.59

^*Bench testing could not sustain the rated 300 W, capping near 255 W sustained; surge holds only seconds.
^†Figure sourced from our review or registry metadata, not published spec.
^‡Sale/street price; retail struck through at $549.99. Value comparisons assume purchase near this discount.

Carrying it, light loads, want fast turnaround

For solo or minimalist campers moving the unit by hand with small loads—phones, a lamp, a laptop, occasional 12 V gear—who would rather recharge fast and travel light than haul unused capacity.
At 9.1 lbs vs the 535’s ~16.5 lbs, it is nearly half the weight, and its built-in wall charger refills it in about an hour with no separate brick—the single most-praised trait in our review. For a buyer whose loads never approach 288 Wh of overnight drain, the 535’s extra energy is dead weight you carry and wait on.
Usable energy ~250–270 Wh at this light mixed AC and DC regime (288 Wh nameplate less ~12 W inverter idle, which is a meaningful tax only at very low draws). Pure sine, scope-confirmed safe for sensitive electronics. One-hour recharge means a lunch-stop top-up is realistic; the 535 needs 2.5-plus hours.
Neither is a true backpacking unit—Anker’s hiking imagery for the C300 is marketing fantasy—but if it is getting carried at all, the C300 is the one to carry.

Charging cameras, drones, and laptops over USB-C

For content creators or mobile pros topping up camera batteries, drone packs, and laptops between shoots, where USB-C throughput is the entire job.
The C300 carries two 140 W two-way USB-C PD 3.1 ports against the 535’s single 60 W USB-C port—our review calls fast device charging squarely in its wheelhouse. The 535 simply cannot deliver here; a single 60 W port is a generation behind and does not clear the capability floor for this application.
Dual 140 W ports charge two laptops or large packs at full speed simultaneously. DC efficiency is strong (inverter-idle tax bypassed on USB and DC paths), so usable energy sits near ~250–270 Wh at this regime. Lighter to haul to the shoot at 9.1 lbs.
The C300’s USB-C output auto-shuts-off after roughly two hours at low current—irrelevant for active high-wattage charging sessions, but a problem if you tried to trickle a device continuously.

Family or fridge weekend camping and RV

For a pair or family running a 12 V fridge plus lights, fans, and device charging across a two- to three-day trip, with the unit living in the vehicle.
Its 512 Wh vs the C300’s 288 Wh is the difference between rationing and relaxing: our review documents a 60 W mini-fridge running seven-plus hours and a family of four covered for 24 hours with reserve left. Our review names camping its sweet spot. The 500 W ceiling also absorbs the occasional kettle-free spike—air-mattress pump, larger inverter cooler—that the C300’s ~255 W real ceiling would refuse.
Usable energy ~430–460 Wh at this regime. The fridge runs on the DC port (no inverter idle) and aggregate group draw is high enough that idle is proportionally negligible, so the 535 sits near its high-load asymptote. Same LiFePO4 chemistry and five-year warranty as the C300—no longevity penalty for the extra capacity. Better value while it runs: $0.59 per Wh vs $1.04 per Wh.
The C300 is a runner-up only for a minimalist pair with tiny loads who prize the lighter carry and one-hour recharge over runtime—that buyer is really in the lightweight-carry segment.

CPAP and medical overnight backup

For a CPAP user who needs a full, reliable night of power during an outage—especially with the humidifier and heated tube running. Pure sine and full-night watt-hours are hard gates for medical-criticality applications.
At the CPAP regime our review documents a 40 W CPAP running 12-plus hours—or eight to ten nights at 30–60 W—and notes power-saving mode can be disabled so it runs continuously overnight. The C300 fails this gate for the heated and humidified configuration by its own review: with humidifier and heated tube on, measured draw ~54 W yields only 2.5–3.5 hours, insufficient for a full night. Comparing both at the same CPAP load regime, the 535’s 512 Wh clears the night and the C300’s 288 Wh does not.
Usable energy at ~40–54 W CPAP regime: the 535 comfortably delivers a full night-plus; the C300 delivers a full night only in dry mode (humidifier and heat off), where owners got multiple nights. Clean power: the C300 is scope-confirmed pure sine; the 535 is not spec-labeled but our review confirms clean CPAP operation (lower label-certainty, functional confirmation).
The C300 is a runner-up for dry-mode CPAP only. If you sleep without humidity or heat and want the lighter, faster-charging unit, the C300 is a legitimate pick. The moment humidity or heated tube enters, it is out and the 535 is the only one of the two that qualifies.

Multi-day outage, value-first essential backup

For apartment or home buyers who want the most essential-device runtime per dollar through a 12- to 48-hour outage—fridge, router, lamps, phones—managing the unit manually. No heat, no cooking.
At the same ~$300 canonical price, the 535 delivers 512 Wh at $0.59 per Wh vs the C300’s 288 Wh at $1.04 per Wh—nearly twice the stored energy for the same money—plus a 500 W ceiling that covers more of the essential-appliance band the C300’s ~255 W real ceiling locks out. For keeping your gear alive for two days, it carries more of what matters.
Usable energy ~430–460 Wh across the essentials regime (mixed AC and DC, idle tax negligible at these draws).
This verdict rests on the $299.99 canonical sale price. At the $549.99 retail tag the per-watt-hour math flips toward the C300, and our review of the 535 says to buy only on discount. Confirm the price you will actually pay. The C300 is a runner-up only via the always-on UPS fork, which is decisive enough to be its own segment.

Always-on UPS for networking and critical electronics

For keeping a router, modem, NAS, or CPAP-class device alive through grid drops without interruption, unit left plugged in and forgotten. Continuous low draw, ~12–60 W AC, where switchover is critical.
On paper the 535 looks like the better standby box: more capacity, same chemistry, same price. Our research reverses it. The C300’s 10 ms switchover and firmware-fixed auto-restore are confirmed in our review as a real router and modem UPS that does not even blink. The 535’s UPS capability is unknown in spec, and our review actively demotes continuous-UPS use: switchover exists (~20 ms measured by some testers) but the 120 W charge cap means any sustained load above ~120 W drains faster than it refills, and a homelab user found it unworkable for exactly that reason.
The seamless-switchover, set-and-forget UPS job is one the hardware-plus-review combination only confirms for the C300.
The C300 idles at ~12 W, so left on unplugged it self-drains in a day or two; and its USB-C output times out after two hours at low current—run continuous loads off AC or the XT60 input side, not USB-C output. The 535 still wins if the priority is total runtime rather than seamless switchover—that is the multi-day outage segment, not this one.

The bottom line

The C300 wins lightweight carry and solo camping (half the weight, one-hour recharge; capacity does not bind at light loads), USB-C field charging (dual 140 W ports against a single 60 W port that cannot clear the capability floor), and always-on UPS duty (confirmed 10 ms switchover and auto-restore; the 535’s UPS capability is unknown in spec and our review demotes continuous-UPS reliability due to its 120 W charge cap). The 535 wins family and fridge camping (512 Wh vs 288 Wh, the difference between rationing and relaxing), CPAP and medical overnight backup (clears the full-night watt-hour gate at heated-CPAP regime; the C300 fails it except in dry mode), and multi-day outage value-first backup (nearly twice the stored energy for the same money at $0.59 per Wh, conditioned on buying near the $299.99 sale price). Same hardware, read through different weighted axes and load regimes—weight and recharge speed flip the carry verdict, USB-C wattage flips field charging, capacity flips camping and CPAP and outage runtime, confirmed UPS switchover flips always-on networking backup.

Read the full Anker SOLIX C300 review Read the full Anker 535 PowerHouse review