The Greenmagic 400W Portable Foldable Solar Panel (GM400B) and the TWELSEAVAN 400W Portable Solar Panel are evenly matched, rated 4.3 and 4.2. The Greenmagic 400W Portable Foldable Solar Panel (GM400B) leads on value and features. The TWELSEAVAN 400W Portable Solar Panel wins on durability and efficiency. The Greenmagic 400W Portable Foldable Solar Panel (GM400B) costs $77 less ($322.99 vs $399.99).
A low-cost 400 W folding panel for owners of large power stations who camp by the car or RV. The thin spec sheet means checking a station’s voltage limit before buying.
Amazon $322.99A 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 $399.99Prices 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.
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 | Greenmagic 400W Portable Foldable Solar Panel (GM400B) | TWELSEAVAN 400W Portable Solar Panel |
|---|---|---|
| Overall rating | 4.3/5 | 4.2/5 |
| Value 30% | 97 $0.81 per rated watt | 86 $1.00 per rated watt |
| Tested output 20% | 89 not yet tested; estimated 87% of rated watts from the median of the 10 tested panels | 89 not yet tested; estimated 87% of rated watts from the median of the 10 tested panels |
| Portability 15% | 100 18.6 W per lb (21.5 lb (9.8 kg)) | 97 17.6 W per lb (22.7 lb (10.3 kg)) |
| Durability 15% | 36 IP65 | 56 IP65, 2-year warranty |
| Efficiency 10% | 75 23.5% claimed efficiency | 83 24% claimed efficiency |
| Features 10% | 55 built-in kickstand, series/parallel | 35 built-in kickstand |
| Greenmagic 400W Portable Foldable Solar Panel (GM400B) | TWELSEAVAN 400W Portable Solar Panel | |
|---|---|---|
| Output | ||
| Rated power | 400 W | 400 W |
| Tested output | Not tested (estimated 87%) | Not tested (estimated 87%) |
| Efficiency | 23.5% (the listing gives a 21.5-23.5% range without saying cell or module; the top of the range is recorded) | 24% (cell efficiency per the Amazon listing) |
| Cells | Monocrystalline | Monocrystalline |
| Bifacial | No | No |
| Electrical | ||
| Open-circuit voltage (Voc) | - | 46.9 V |
| Voltage at max power (Vmp) | - | 40 V |
| Short-circuit current (Isc) | - | 10.6 A |
| Current at max power (Imp) | - | 10 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 |
| USB ports | None | - |
| Build | ||
| Weight | 21.5 lb (9.8 kg) | 22.7 lb (10.3 kg) |
| Folded size | 32.09 x 31.30 x 1.97 in | 26 x 35.5 in |
| Unfolded size | - | 35.5 x 98.5 in |
| Kickstand | Yes | Yes |
| Water resistance | IP65 | IP65 |
| Warranty | - | 2 years |
