TWELSEAVAN 400W Portable Solar Panel
#6 in LargeFull review
A 400 W folding panel for owners of large power stations that accept around 50 V of solar input. Small-station owners need a lower-voltage panel.
Amazon $399.99$399.99
The TWELSEAVAN 400W Portable Solar Panel is the better portable solar panel overall, rated 4.2 to 3.3. The TWELSEAVAN 400W Portable Solar Panel leads on value, portability and efficiency. The EcoFlow 400W Portable Solar Panel wins on features. The TWELSEAVAN 400W Portable Solar Panel costs $299.01 less ($399.99 vs $699).
EcoFlow 400W Portable Solar Panel
#14 in LargeFull review
For owners of large EcoFlow DELTA-class stations who want the most watts from a single folding panel and will mostly set it up near the car. Campers who carry gear any distance are better off with two smaller panels.
Amazon $699 EcoFlow $699$699
Prices were last checked October 21, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Which should you buy?
- Choose the TWELSEAVAN 400W Portable Solar Panel for value ($1.00 per rated watt vs $1.75 per rated watt), portability (17.6 W per lb (22.7 lb (10.3 kg)) vs 11.3 W per lb (35.3 lb (16 kg))) and efficiency (24% claimed efficiency vs 22.4% claimed efficiency).
- Choose the EcoFlow 400W Portable Solar Panel for features (built-in kickstand, series/parallel vs built-in kickstand).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every large portable solar panel; a clear win is highlighted. How we rank explains each one.
| Factor weight | TWELSEAVAN 400W Portable Solar Panel | EcoFlow 400W Portable Solar Panel |
|---|---|---|
| Overall rating | 4.2/5 | 3.3/5 |
| Value 30% | 86 $1.00 per rated watt | 43 $1.75 per rated watt |
| Tested output 20% | 89 not yet tested; estimated 87% of rated watts from the median of the 10 tested panels | 54 best measured 76% of rated watts (1 test) |
| Portability 15% | 97 17.6 W per lb (22.7 lb (10.3 kg)) | 44 11.3 W per lb (35.3 lb (16 kg)) |
| Durability 15% | 56 IP65, 2-year warranty | 60 IP68, 1-year warranty |
| Efficiency 10% | 83 24% claimed efficiency | 57 22.4% claimed efficiency |
| Features 10% | 35 built-in kickstand | 55 built-in kickstand, series/parallel |
Independent output tests
TWELSEAVAN 400W Portable Solar Panel
No independent test published yet.
EcoFlow 400W Portable Solar Panel
| Tested by | Measured peak | Of rated | Conditions |
|---|---|---|---|
| Mighty Gadget | 305 W | 76% | Highest input shown on an EcoFlow DELTA 2 after adjusting the angle, early afternoon in a partly shaded garden in the north of the UK, mixed sun and cloud, September 2022; input mostly settled between 150 and 250 W |
Specifications
| TWELSEAVAN 400W Portable Solar Panel | EcoFlow 400W Portable Solar Panel | |
|---|---|---|
| Output | ||
| Rated power | 400 W | 400 W |
| Tested output | Not tested (estimated 87%) | 305 W (76%) |
| Efficiency | 24% (cell efficiency per the Amazon listing) | 22.4% (22.40% in EcoFlow's spec table, cell or module not stated; the US product page says up to 23% and labels the option 22.6%) |
| Cells | Monocrystalline | Monocrystalline |
| Bifacial | No | No |
| Electrical | ||
| Open-circuit voltage (Voc) | 46.9 V | 48 V |
| Voltage at max power (Vmp) | 40 V | 41 V |
| Short-circuit current (Isc) | 10.6 A | 11 A |
| Current at max power (Imp) | 10 A | 9.8 A |
| Series / parallel | - | Yes |
| Connections | ||
| Output connector | MC4 | MC4 |
| Cables included | 9.8 ft 5-in-1 MC4 cable (Anderson, XT60, DC8020, DC7909, DC5521), 3 DC adapters | MC4 to XT60 |
| USB ports | - | None |
| Build | ||
| Weight | 22.7 lb (10.3 kg) | 35.3 lb (16 kg) |
| Folded size | 26 x 35.5 in | - |
| Unfolded size | 35.5 x 98.5 in | 42.0 x 94.1 x 1.0 in |
| Kickstand | Yes | Yes |
| Water resistance | IP65 | IP68 |
| Warranty | 2 years | 1 years |