Head-to-head test
EcoFlow DELTA 2 vs Anker SOLIX C800
The DELTA 2 now costs $100 less than the SOLIX C800 while holding 256 more watt-hours and putting out 600 more continuous watts — the only reasons left to pick the C800 are a quieter fan and 3.2 fewer pounds.
Written by Ian SchneiderUpdated
Solar & Off-Grid Tester, Station Arena Test Desk
EcoFlow
DELTA 2
3,128Power Score · Appliance Class
$499.00 list · direct from EcoFlow
Anker
SOLIX C800
2,245Power Score · Appliance Class
$599.00 list · direct from Anker
Spec deltas
The EcoFlow DELTA 2 costs $499, holds 1,024Wh, and outputs 1,800W continuous. The Anker SOLIX C800 costs $599 for 768Wh and 1,200W continuous — $100 more for 256Wh less capacity, 600W less output, and a smaller surge ceiling, 1,600W against the DELTA 2's 2,700W.
The DELTA 2 does come with a genuine catch: its fans trigger above roughly 120W and hold near 50dB at full draw, while the C800 stays close to silent under 500WA1B7. That's the one place the extra $100 buys you something.
Both run identical 3,000-cycle, 5-year warranty terms, so durability isn't in question for either. What's in question is whether a quieter fan and 3.2 fewer pounds (23.8 lbs against 27 lbs) are worth $100 and 256Wh less capacity. Framed that way, this isn't a close call.
What the Numbers Reveal
Each conclusion stated first — the numbers behind it on one line, the full analysis below.
continuous output
Add the 1,100W-bigger surge ceiling (2,700W against 1,600W) and the C800 isn't just outpriced — it's outbuilt on every hard number that costs money to manufacture, while charging more for less of each one.
DELTA 2 costs $499 against the SOLIX C800's $599 — the DELTA 2 is $100 cheaperDELTA 2 holds 1,024Wh against the C800's 768Wh, 256Wh more capacityDELTA 2 outputs 1,800W continuous against the C800's 1,200W, 600W more
Why it mattersAnyone comparing these two on the spec sheet alone has no reason left to pick the pricier, smaller unit — the case for the C800 has to come from somewhere other than the numbers.
And if your gear list ever grows past what either handles today, only one of these two has anywhere left to go. The DELTA 2 takes an expansion battery without replacing the base unit; outgrowing the C800 means buying an entirely separate power station. That headroom now comes bundled with the cheaper unit, not the pricier one.
Tailgate Party needs 670Wh: the DELTA 2 uses 77% of its capacity, the C800 needs 103% and can't finish the loadOnly the DELTA 2 accepts EcoFlow expansion batteries; the C800 is sealed at 768Wh with no expansion path
Why it mattersBuyers whose loads might creep up over time — more gear, more people, more days away — should treat the expansion port as a free hedge, since it no longer costs extra to keep it.
The real tiebreaker is decibels, not watt-hours. A CPAP alone won't push the DELTA 2 past the roughly-120W point where its fans engageA1, but sharing the outlet with anything else overnight will. The C800 has headroom to spare below its 500W near-silent ceiling before it makes any noise at allB7.
DELTA 2 fans trigger above roughly 120W and hold near 50dB at full 1,800W outputA1The C800 stays close to silent under 500W loads, with only a mild hum at its 1,200W ceilingB7CPAP Overnight needs 320Wh — 37% of the DELTA 2's capacity and 49% of the C800's
Why it mattersAnyone running this two feet from a bed overnight should weigh the noise gapA1B7 as heavily as the capacity numbers when choosing between these two.
cost / lifetime kWh
Every dollar figure on this page now points the same direction — purchase price, cost per lifetime kWh, cost per warranty year. There's no financial argument left for the C800; whatever case it still has is about weight or noise, not money.
Lifetime cost lands at $0.16 per kWh for the DELTA 2 against $0.26 for the C800The DELTA 2 also costs $100 less up front: $499 against $599Cost per warranty year runs $100 for the DELTA 2 against $120 for the C800
Why it mattersBuyers deciding on pure cost-efficiency can stop reading here — the DELTA 2 wins every cost figure in this comparison, not only the sticker price.
The specific dimensions that decide these two units — everything else is a tie.
Lifetime Value
Selected because: The price flip makes cost-per-kWh the headline now — the cheaper sticker and the cheaper energy cost point the same direction.
cost / lifetime kWh
Cost per lifetime kWh is $0.16 for the DELTA 2 against $0.26 for the C800 — a real ten-cent gap, stacked on top of a $100 lower purchase price rather than offsetting it. Cost per warranty year follows the same pattern: $100 a year for the DELTA 2, $120 for the C800, on identical 5-year, 3,000-cycle terms.
Every figure on the cost side of this page points at the DELTA 2. If the C800 has an argument, it isn't in the price column.
Your Life, Your Pick
Selected because: Tailgate Party and CPAP Overnight are the only two loads where these units actually diverge.
Weekend Camping, the 8-Hour Blackout, Remote Workday, and Van Life Daily all beat both units outright — this pair isn't sized for a multi-day trip or a full day of appliances, so neither wins those by default. CPAP Overnight is where capacity stops being the question: both clear it with room to spare, 37% of the DELTA 2's tank against 49% of the C800's.
Tailgate Party is the one load that actually separates them. The C800 needs 103% of its battery to cover it and runs out before the afternoon does; the DELTA 2 finishes at 77%, with real reserve left for whatever gets plugged in next.
What the Specs Don't Tell You
Selected because: Noise, expansion, and warranty are the three gotchas firing, and noise is the one real reason left to still consider the C800.
Fan noise is the honest catch on the DELTA 2 side. Its fans trigger above roughly 120W and hold near 50dB at full output, while the C800 stays close to silent under 500W with only a mild hum at its ceilingA1B7. It's the one column here where the cheaper unit is also the louder one.
Warranty coverage is identical on paper: 5 years, 3,000 cycles, on both, so the gap in cost-per-warranty-year is arithmetic on the sticker prices, not unequal protection. Expansion is the DELTA 2's one asymmetric advantage — the C800 is sealed at 768Wh for the life of the unit, full stop.
Growth Path
Selected because: Expansion used to be a paid upgrade on the DELTA 2; now it's bundled with the cheaper unit.
solar input
The DELTA 2 is the only one of these two built to grow. Add an EcoFlow expansion battery later and the base unit doesn't change. The C800 has no equivalent: 768Wh today is 768Wh for as long as you own it.
That door comes with the cheaper unit here, not the pricier one — there's no longer a trade-off between saving money today and keeping options open tomorrow.
Strengths & trade-offs
EcoFlow DELTA 2
Strengths
- +Costs $100 less
- +Larger battery capacity
- +Higher AC output
- +Faster solar charging
Trade-offs
- –No major technical downsides compared to rival.
Anker SOLIX C800
Strengths
- +Lighter by 3.2 lb
Trade-offs
- –Weaker inverter (-600W) limits appliance compatibility.
- –Sealed capacity — the DELTA 2 can add batteries to grow past 768Wh; this one can't.
Will It Power Your Gear?
Scenario math and per-appliance runtimes, modeled from the spec record.
Scenario verdicts
We ran the math on six real-world scenarios. Here's which unit survives your actual life.
SCN-01 · 2 nights · needs 2,100Wh
Weekend Camping
Two nights off-grid with essential comfort
Neither unit
Neither unit can fully handle this scenario (needs 2,100Wh). You'd need a higher-capacity station or to cut back on usage.
Battery budget usedlower = more headroom
LOAD Phone Charger 15W×6h · LED Lights 40W×8h · Box Fan 75W×14h · CPAP Machine 40W×16h
SCN-02 · 8 hours · needs 1,645Wh
8-Hour Blackout
Keep the essentials running through a night without power
Neither unit
Neither unit can fully handle this scenario (needs 1,645Wh). You'd need a higher-capacity station or to cut back on usage.
Battery budget usedlower = more headroom
LOAD Fridge 150W×8h · Router + Modem 20W×8h · LED Lights (4 bulbs) 40W×6h · Phone Charger 15W×3h
SCN-03 · 8 hours · needs 320Wh
CPAP Overnight
Sleep therapy without interruption — the #1 medical use case
DELTA 2
Both units clear this easily on capacity alone, 37% for the DELTA 2 and 49% for the C800. The tiebreak is decibels: the C800 is spec'd at 45dB against the DELTA 2's 50dB, so if this sits near your bed, quiet may matter more than the small capacity edge.
Battery budget usedlower = more headroom
LOAD CPAP Machine 40W×8h
SCN-04 · 8 hours · needs 910Wh
Remote Workday
Full work day off-grid without power anxiety
Neither unit
Neither unit can fully handle this scenario (needs 910Wh). You'd need a higher-capacity station or to cut back on usage.
Battery budget usedlower = more headroom
LOAD Laptop 60W×8h · External Monitor 30W×8h · Router + Modem 20W×8h · Phone Charger 15W×2h
SCN-05 · 4 hours · needs 670Wh
Tailgate Party
Game day power for the crew
DELTA 2
The C800 can't finish a typical tailgate load on its own battery — it needs more than it has. The DELTA 2 covers the same afternoon at 77% and still has capacity left, and it's the cheaper unit doing it.
Battery budget usedlower = more headroom
LOAD Blender 400W×0.5h · LED TV (55") 80W×4h · Bluetooth Speaker 15W×4h · Phone Charger (×3) 45W×2h
SCN-06 · 24 hours · needs 4,685Wh
Van Life Daily
A full day of mobile living — the ultimate endurance test
Neither unit
Neither unit can fully handle this scenario (needs 4,685Wh). You'd need a higher-capacity station or to cut back on usage.
Battery budget usedlower = more headroom
LOAD Mini-Fridge 150W×24h · Laptop 60W×4h · Phone Charger 15W×3h · LED Lights 40W×5h · Fan 75W×8h
The Load Test
RUNTIME = (Wh × 0.85) ÷ LOAD
None of the six scenarios above exactly yours? Build it. Toggle what you'd plug in; both units are tested against the combined draw.
Essentials
Comfort & Convenience
High-Draw Appliances
Test duration
8h
Continuous draw
205W
Projected runtime
For this load: DELTA 2 runs 4.2h vs 3.2h.
$499 list · direct from EcoFlow
Modeled from the spec record — same math as the tables below. Methodology
Runtime by appliance
Real-world runtime estimates for common appliances, modeled at 85% inverter efficiency.¹
Essentials
The basics you need runningscale 0–58hComfort & Convenience
Makes off-grid life actually enjoyablescale 0–11.6hHigh-Draw Appliances
These reveal the real limitsscale 0–0.9h¹ Runtime = (capacity × 0.85) ÷ appliance watts. Within each group, all bars share one time scale (the group's longest runtime), so lengths are comparable across appliances; identical runtimes collapse into a single blue/orange bar. Actual runtime varies with battery age, temperature, and simultaneous loads — see methodology.
Conclusion
July 26, 2026
Verdict: the DELTA 2
The DELTA 2 is both the cheaper unit and the more capable one now: $499 against $599, for 256Wh more capacity and 600W more continuous output, plus the only expansion path between the two. It also takes both scenarios where these units genuinely differ. It covers Tailgate Party at 77% of its tank while the C800 needs 103% and can't finish, and it clears CPAP Overnight with more room to spare. What it doesn't win is quiet: its fans trigger above roughly 120W and hold near 50dB at full output, against a C800 that stays close to silent under 500WA1B7. Buy the C800 only if that noise gap, or its 3.2-lb weight edge, matters more to you than everything else on this page. Otherwise the DELTA 2 is the straightforward buy.
Editor-assigned confidence, based on cited owner research and spec analysis.
List prices as of July 26, 2026. The links below open EcoFlow's and Anker's current prices.
$499.00 list · direct from EcoFlow
or check the SOLIX C800 price$599.00 list
Written by Ian Schneider, Solar & Off-Grid Tester · Station Arena Test Desk · Updated July 26, 2026
Measured Data
Benchmark scores and the full spec record, side by side.
Benchmark scores
Not rated for both units (minimum threshold unmet): RV Living, Home Backup, Food Truck.
Full specifications
ᵈ Derived: price ÷ rated capacity. See the data behind our comparisons →
Comparison ToolAdd more power stations, side by sideOpen Tool →How these numbers are produced
Numeric verification
Every figure on this page traces to our spec database or arithmetic on it — no estimated numbers.
Owner claims
Statements about owner experience are cited to published reviews — see Sources & Research Notes below.
Runtime model
Runtime = (rated capacity × 0.85 inverter efficiency) ÷ device wattage. Solar recharge estimates assume panels deliver 70% of rated output. Cold weather, battery age, and stacked loads reduce real-world results.
Power Score
Computed from 14 published spec dimensions, weighted per use-case bench. Higher is better; a unit must meet a bench's minimum threshold to be rated.
See the full weight table and data sourcing on our methodology page →Class ranking (the star rating)
Each unit's star score is a category ranking, not customer reviews — no buyer opinions feed it. We score every station on size-independent quality (value, output, portability, endurance, ports, warranty, and more), then percentile-rank it against the other units in its capacity class, so a class-leading compact unit and a class-leading whole-home unit can both earn 5★. Here, DELTA 2 rates 4.0/5 (39th percentile of 24 Everyday-class units), and SOLIX C800 rates 4.1/5 (50th percentile of 19 Compact-class units).
How the class ranking is computed →Test Notes & Caveats
Hidden gotchas and advantages we spotted that you won't find on the product page.
One Fan Runs During Normal Use, One Doesn't
The DELTA 2 is spec'd at 50dB; the C800 at 45dB. That five-decibel gap is now the main reason left to still consider the pricier, smaller-capacity unit.
Only One of These Grows
The DELTA 2 accepts EcoFlow expansion batteries; the C800 is sealed at 768Wh for good. That headroom comes bundled with the cheaper unit here, not the pricier one.
Same Coverage, Different Price
Both carry a 5-year warranty over 3,000 cycles — identical terms. The gap in cost-per-warranty-year, $100 for the DELTA 2 against $120 for the C800, comes from paying more for the C800's smaller battery, not unequal protection.
Full record above — the Test Desk pick is the DELTA 2.
Check DELTA 2 price →or check the SOLIX C800 priceOwnership Analysis
What happens after you buy — true cost of ownership, brand trust, and growth potential.
Lifetime value
Service lifeyears at one full cycle per day
Lifetime energy delivered
Cost per delivered kWh
│ warranty ends · Reaching the cycle rating means ~80% capacity remains — degraded, not dead.
Analyst note
The DELTA 2 wins on both sticker price and long-term value. At $0.16/kWh over its lifetime, it's meaningfully cheaper to own. Clear value winner.
Delivers each lifetime kWh for $0.10 less — check the DELTA 2 price →
Brand trust
EcoFlow
Ecosystem
Largest in portable power — 12-15 models across DELTA Pro, DELTA 3, and RIVER 3 series, plus solar panels and smart home panels
Support
US-based phone/email/chat support (1-800-368-8604). Experiences are polarized — many report hassle-free prepaid-label replacements, but others report long waits and refurbished units sent for new claims. Pro tip: buying from Costco or Amazon gives you a stronger return safety net.
Community
Largest community in the space — Reddit r/Ecoflow_community (~31K members), multiple Facebook groups, and an official community forum
App experience
Rated 4.6/5 iOS (~8,400 ratings) · 4.2/5 Android (~17,000 ratings)
Unique strength
Fastest-charging technology (X-Stream), deepest product ecosystem, and most active innovation cadence. Supports up to 180kWh modular expansion with DELTA Pro Ultra X.
Worth knowing
The Oct 2025 DELTA Max 2000 recall (overheating/fire risk, 6 incidents) is worth noting. Also tested subscription paywalls for advanced app features in early 2025 before community backlash paused the plan. No parts or service offered out of warranty.
Anker
Ecosystem
7-8 SOLIX portable power stations across C-series (compact) and F-series (flagship), plus the X1 home energy system
Support
US-based support. Historically known for incredible no-hassle replacements, but recent reports describe AI-driven support agents giving generic responses and complex return logistics for heavy units (hazmat shipping). The Anker brand reputation is still strong, but SOLIX-specific support quality is trending down.
Community
Moderate — active Reddit (r/Anker, r/AnkerSOLIXCommunity) and growing. Benefits from Anker's massive consumer electronics brand awareness.
App experience
Rated 4.5/5 iOS (~1,100 ratings) · 4.3/5 Android
Unique strength
Parent brand trust from Anker's consumer electronics dominance. InfiniPower technology for long cycle life. Strong $/Wh value in the mid-size and larger units — the S2000, F2600 and C1000 are among the better buys per watt-hour in the catalog.
Worth knowing
Support quality appears to be declining from its historically excellent level. Firmware updates have removed features without warning. Expansion ecosystem is smaller than EcoFlow's.
Analyst note
EcoFlow positions itself as a mid-to-premium brand with stronger support infrastructure, while Anker competes on value. The question is whether the EcoFlow ecosystem and support premium is worth it for your use case.
Growth path
DELTA 2
EXPANDABLESupports EcoFlow expansion batteries, so you can add capacity later without replacing the base unit — useful if your needs may climb past 1,024Wh.
Accepts up to 500W of solar. Suitable for a 1-2 panel setup.
Generous port selection supports complex multi-device setups.
Expansion batteries are EcoFlow-specific. You're investing in the EcoFlow ecosystem.
SOLIX C800
FIXED CAPACITYFixed at 768Wh, with no expansion — so size it for your needs up front rather than planning to add capacity later.
Accepts up to 300W of solar. Limited to a single portable panel.
Adequate ports for most setups, but heavy users may want a power strip.
Realistic full solar rechargeat 70% of rated panel output — see methodology
Analyst note
The SOLIX C800 is sealed at 768Wh, which is fine if that covers you. The DELTA 2 starts at 1,024Wh and can grow beyond it with EcoFlow expansion batteries — real headroom the SOLIX C800 doesn't have if your needs climb toward partial-home backup.
What Owners Report
Patterns from published owner reports and long-term reviews — every claim cited to its source below.
EcoFlow DELTA 2
Fan noise is the DELTA 2's one recurring complaint across reviewers: the fans trigger above roughly 120W and hold near 48-55dB at full 1,500-1,800W draw, meaning anyone running medical equipment above that threshold in a bedroom either lives with the noise or routes a cable out of the roomA1. Charging at 1,200W has been compared to a gaming laptop under load, though the charge rate can be throttled down in the app to quiet itA2.
Past the fan, the reputation holds up: one reviewer ran the unit through 18 months of outages, camping trips, and daily home-office use, and came away praising the fast charging, LiFePO4 reliability, and expansion pathA3. EcoFlow has reportedly signaled a firmware fix for the noise, following its pattern on other models, though nothing had shipped as of the most recent coverageA4.
“When charging at 1200W the fans sound like a gaming laptop, though you can lower the charging speed in the app to silence it.”
Sources
portablepowerlab.com
Anker SOLIX C800
One reviewer dropped the C800 from tailgate height, about 30 inches, onto gravel and came away with only minor scuffingB1, and a second independently called its chassis rugged and impact-resistantB14. It backs that build quality with real output too — a 1,000W coffee maker ran 42 minutes straight without issueB3.
The honest gaps: no IP weather rating, so reviewers keep it covered outdoorsB2, and at just over 23 lbs it's flagged as heavy for carrying any real distance on footB12. Set against the DELTA 2's fan complaints above, though, the C800 draws no such reports — it stays near-silent under 500W loads with only a mild hum at its ceilingB7.
“We dropped it from a tailgate (30 inches) onto gravel—only minor scuffing, no damage.”
Sources
backuppowerhub.com · portablepowergeek.co.uk · batteryskills.com · batteryessence.com · toolsandtoys.net · bikmantech.com
Sources & Research Notes
Every owner claim in this report is traceable to a published source. The bracketed references above resolve here.
Recurring owner themes
- Fan noise under moderate-to-high load is the dominant, repeatedly-cited complaint; the fan spins up above ~120W. [DELTA 2 · 3 entries]
- Build quality/chassis is repeatedly called solid and drop-resistant, but reviewers flag the lack of an IP weather rating as a real-world caveat for outdoor use. [SOLIX C800 · 3 entries]
- The 58-minute AC fast-recharge is the single most-mentioned standout feature, praised as faster than rivals like the Jackery 700. [SOLIX C800 · 2 entries]
- Reviewers note the unit can briefly exceed its 1200W rating for heavy appliances, but caution it can't sustain full-size continuous loads like a full-size fridge. [SOLIX C800 · 2 entries]
- Long 5-year warranty and strong retailer star ratings are cited as reassurance/value signals. [SOLIX C800 · 2 entries]
- Weight (~23-24 lbs) is repeatedly flagged as a downside relative to lighter rivals despite the compact footprint. [SOLIX C800 · 2 entries]
- A1
“Fans trigger at anything above 120 watts; at maximum load (1,500–1,800W) they run continuously at ~48–55 dB. Powering medical equipment above 120W in a bedroom means listening to the fans or running an extension cable out of the room.”
portablepowerlab.com — EcoFlow Delta 2 Review: 6 Months of Real Use; PCWorld — EcoFlow Delta 2 review · 2026 · [negative]
- A2
“When charging at 1200W the fans sound like a gaming laptop, though you can lower the charging speed in the app to silence it.”
PCWorld — EcoFlow Delta 2 power station review · 2026 · [mixed]
- A3
“After 18 months of real-world testing through multiple power outages, camping trips, and daily home-office use, the unit earned recognition for fast charging, reliable LiFePO4 battery chemistry, and expandability.”
portablepowerlab.com — EcoFlow Delta 2 Review: 6 Months of Real Use · 2026 · [positive]
- A4
“EcoFlow officials indicated they plan to address the fan noise in an upcoming firmware update, as they have for other models after release.”
portablepowerlab.com — EcoFlow Delta 2 Review · 2026 (dated claim — may be partially addressed) · [mixed]
- B1
“We dropped it from a tailgate (30 inches) onto gravel—only minor scuffing, no damage.”
backuppowerhub.com — Anker SOLIX C800 Review: Best Budget Power Station? · 2025-12 · [positive]
- B2
“However, the C800 lacks IP weather rating. Keep it covered when camping.”
backuppowerhub.com — Anker SOLIX C800 Review: Best Budget Power Station? · 2025-12 · [negative]
- B3
“A 1,000W coffee maker ran 42 minutes straight.”
backuppowerhub.com — Anker SOLIX C800 Review: Best Budget Power Station? · 2025-12 · [positive]
- B7
“Zero fan noise under 500W loads, unlike louder competitors (e.g., Bluetti EB55). Only a mild hum at max load.”
batteryskills.com — Anker SOLIX C800 Portable Power Station Review · 2025-10 · [positive]
- B12
“At 23.15 lbs (10.5 kg), this is too heavy for carrying far on foot. For hiking, a smaller, lighter power bank under 5 lbs is a better fit.”
batteryessence.com — Anker SOLIX C800 Portable Power Station 768Wh Review · 2026-03 · [negative]
- B14
“Both models feature a rugged, durable chassis made from high-quality, impact-resistant materials, ready to withstand the rigors of outdoor use.”
bikmantech.com — Anker SOLIX C800 vs C800 Plus - Ultimate Camping Power Comparison · 2025-06 · [positive]
Research compiled July 26, 2026.
Who Should Buy Which
Buy the DELTA 2 if you…
- →You want more capacity, more output, and a lower price at the same time — the DELTA 2 beats the C800 on all three right now.
- →Your gear list might grow. The expansion port is the DELTA 2's alone, and it no longer costs a premium to keep that option open.
Buy the SOLIX C800 if you…
- →Quiet matters more than capacity to you — this unit sits within a couple feet of a bed or a desk and you don't want to hear it during normal use.
- →3.2 fewer pounds is worth $100 more to you on its own, independent of anything else here.
If neither fits
If your real need is a two-night camping trip (about 2,100Wh) or an 8-hour multi-appliance blackout (about 1,645Wh), both of these fall well short — even the DELTA 2 would need close to double its usable capacity for the blackout scenario. Look at a larger-capacity unit from either brand instead of choosing between these two.
The Bottom Line
The DELTA 2 wins this one on price and capability at the same time: $100 less for 256Wh more capacity, 600W more continuous output, and the only expansion path between the two. That combination settles almost every version of this decision before noise or weight even enter it.
The C800's remaining case is narrow but real: quieter at light loads (45dB against 50dB), 3.2 lbs lighter, and enough for a CPAP or a short blackout on its own. If neither of those is why you're buying, take the DELTA 2 and keep the change.
Frequently Asked Questions
Answers drawn from the spec record and cited owner research.
Which one should I buy right now — the EcoFlow DELTA 2 or the Anker SOLIX C800?
The DELTA 2, in almost every case. It costs $100 less than the C800 ($499 against $599) while holding 256Wh more capacity, 600W more continuous output, and a bigger surge ceiling. The only reasons to still pick the C800 are a quieter fan and 3.2 fewer pounds.
Which one is quieter?
The C800, clearly. It stays close to silent under 500W loads with only a mild hum at its 1,200W ceiling, while the DELTA 2's fans trigger above roughly 120W and hold near 50dB at full output — a threshold low enough that ordinary use keeps them running.
Can the C800 be expanded later if my power needs grow?
No. The C800 is a sealed 768Wh system for the life of the unit. The DELTA 2 accepts EcoFlow expansion batteries, and now that it's also the cheaper unit, that headroom doesn't cost anything extra to keep open.
Which one is cheaper to own long-term?
The DELTA 2, by a real margin. It runs $0.16 per lifetime kWh against $0.26 for the C800, and $100 a year in warranty-adjusted cost against $120 — on top of costing $100 less to buy. Every cost figure here favors the DELTA 2.
Which one should I buy for a CPAP machine?
Lean toward the C800 if this unit sits within a couple feet of your bed and anything else might share the outlet overnight — it's spec'd at 45dB against the DELTA 2's 50dB. Both comfortably cover a CPAP overnight on raw capacity alone, well under half of either unit's tank, so the decision here is about decibels, not watt-hours.
Where to buy
EcoFlow DELTA 2Pick
$499.00
$499.00 list · direct from EcoFlow
Anker SOLIX C800
$599.00
$599.00 list · direct from Anker
Prices may vary by retailer and are subject to change.