The Callsun 420W (2 x 210W) Bifacial 2-Pack is the better rigid solar panel overall, rated 4.0 to 3.9. The Callsun 420W (2 x 210W) Bifacial 2-Pack leads on value. The Callsun 420W (2 x 210W) Bifacial 2-Pack costs $20.02 less ($299.97 vs $319.99).
A good-value pair for a 24 V RV, van or cabin system with an MPPT controller, or for a power station wired in parallel. Owners of 12 V PWM setups should pick a lower-voltage panel.
Amazon $299.97A strong value for a 400 W ground mount, shed roof or large RV roof, and a good match for power stations with a 60 V solar input. Mostly sold as a pair on Amazon.
Amazon $319.99Prices were last checked October 26, 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 150 W and up rigid solar panel; a clear win is highlighted. How we rank explains each one.
| Factor weight | Callsun 420W (2 x 210W) Bifacial 2-Pack | Callsun 400W (2 x 200W) Bifacial 2-Pack |
|---|---|---|
| Overall rating | 4.0/5 | 3.9/5 |
| Value 45% | 75 $0.71 per rated watt | 67 $0.80 per rated watt |
| Tested output 15% | 50 not yet independently tested (neutral score used) | 50 not yet independently tested (neutral score used) |
| Durability 25% | 100 IP68, 10-year warranty | 100 IP68, 10-year warranty |
| Efficiency 15% | 38 19.9% module efficiency (from size and rated power) | 38 19.9% module efficiency (from size and rated power) |
| Callsun 420W (2 x 210W) Bifacial 2-Pack | Callsun 400W (2 x 200W) Bifacial 2-Pack | |
|---|---|---|
| Output | ||
| Rated power | 420 W | 400 W |
| Module efficiency | 19.9% (rated power over panel area) | 19.9% (rated power over panel area) |
| Claimed efficiency | 25.6% (cell efficiency; no module efficiency published) | 25% (cell efficiency) |
| Cells | Monocrystalline (N-type, 16BB, quarter-cut cells, wired as two parallel halves for shade tolerance) | Monocrystalline (N-type, 16BB, split into two parallel halves for shade tolerance) |
| Bifacial | Yes | Yes |
| Electrical | ||
| Open-circuit voltage (Voc) | 40.3 V | 27.3 V |
| Voltage at max power (Vmp) | 34.2 V | 23.7 V |
| Short-circuit current (Isc) | 6.5 A | 8.9 A |
| Current at max power (Imp) | 6.1 A | 8.4 A |
| Voc temperature coefficient | -0.2%/°C | - |
| Series / parallel | Yes | Yes |
| Connections | ||
| Output connector | Solar connectors | MC4-compatible solar connectors |
| Build | ||
| Weight | - | 47.6 lb (21.6 kg) |
| Dimensions | 54.2 x 30.2 x 1.4 in (each panel) | 51.34 x 30.31 x 1.58 in (each panel) |
| Frame | anodized aluminum alloy | anodized aluminum alloy |
| Glass | 3.2 mm tempered | 3.2 mm tempered |
| Junction box rating | IP68 | IP68 |
| Warranty | 10 years | 10 years |
| Output warranty | 84.5% output after 25 years | 84.5% output after 25 years |
| Released | 2026-08 | 2025-06 |
