The Greenmagic 400W Portable Foldable Solar Panel (GM400B) is the better portable solar panel overall, rated 4.3 to 4.1. The Greenmagic 400W Portable Foldable Solar Panel (GM400B) leads on portability, efficiency and features. The ALLPOWERS SP037 400W Foldable Solar Panel wins on durability. The ALLPOWERS SP037 400W Foldable Solar Panel costs $23.99 less ($299 vs $322.99).
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 cheap way to put 400 W into a large power station from a campsite or driveway, as long as you don’t need to carry it far. Hikers and small-station owners should look at lighter, lower-voltage panels.
Amazon $299 ALLPOWERS $299Prices 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) | ALLPOWERS SP037 400W Foldable Solar Panel |
|---|---|---|
| Overall rating | 4.3/5 | 4.1/5 |
| Value 30% | 97 $0.81 per rated watt | 100 $0.75 per rated watt |
| Tested output 20% | 89 not yet tested; estimated 87% of rated watts from the median of the 10 tested panels | 100 best measured 96% of rated watts (1 test) |
| Portability 15% | 100 18.6 W per lb (21.5 lb (9.8 kg)) | 32 9.8 W per lb (40.8 lb (18.5 kg)) |
| Durability 15% | 36 IP65 | 80 IP67, 2-year warranty |
| Efficiency 10% | 75 23.5% claimed efficiency | 50 22% claimed efficiency |
| Features 10% | 55 built-in kickstand, series/parallel | 35 built-in kickstand |
No independent test published yet.
| Tested by | Measured peak | Of rated | Conditions |
|---|---|---|---|
| The Gadgeteer | 385 W | 96% | December in Michigan on a semi-sunny day; 329 W on a fairly cloudy day. The review does not say what displayed the reading. |
| Greenmagic 400W Portable Foldable Solar Panel (GM400B) | ALLPOWERS SP037 400W Foldable Solar Panel | |
|---|---|---|
| Output | ||
| Rated power | 400 W | 400 W |
| Tested output | Not tested (estimated 87%) | 385 W (96%) |
| Efficiency | 23.5% (the listing gives a 21.5-23.5% range without saying cell or module; the top of the range is recorded) | 22% (solar conversion rate per ALLPOWERS' spec table (cell or module not stated); the manual gives 19-23%) |
| Cells | Monocrystalline | Polycrystalline |
| Bifacial | No | No |
| Electrical | ||
| Open-circuit voltage (Voc) | - | 45.3 V |
| Voltage at max power (Vmp) | - | 37.4 V |
| Short-circuit current (Isc) | - | 11.4 A |
| Current at max power (Imp) | - | 10.6 A |
| Series / parallel | Yes | - |
| Connections | ||
| Output connector | MC4 | MC4 |
| Cables included | - | MC4 to XT60, MC4 to DC5525 + DC8020 adapter |
| USB ports | None | - |
| Build | ||
| Weight | 21.5 lb (9.8 kg) | 40.8 lb (18.5 kg) |
| Folded size | 32.09 x 31.30 x 1.97 in | 41.26 x 20.94 x 2.56 in |
| Unfolded size | - | 41.26 x 104.72 x 0.2 in |
| Folding sections | - | 5 |
| Kickstand | Yes | Yes |
| Water resistance | IP65 | IP67 |
| Warranty | - | 2 years |
