The Callsun 450W Bifacial Double-Glass is the better rigid solar panel overall, rated 4.1 to 4.0. The Callsun 450W Bifacial Double-Glass leads on efficiency. The Callsun 420W (2 x 210W) Bifacial 2-Pack wins on value. The Callsun 420W (2 x 210W) Bifacial 2-Pack costs $70.02 less ($299.97 vs $369.99).
A large bifacial panel with a longer warranty than most, for a home rooftop, shed or ground-mount array on a 24 V or 48 V system or a grid-tie inverter. Too big and too high-voltage for most RV and van setups.
Amazon $369.99A 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 $299.97Prices 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 450W Bifacial Double-Glass | Callsun 420W (2 x 210W) Bifacial 2-Pack |
|---|---|---|
| Overall rating | 4.1/5 | 4.0/5 |
| Value 45% | 65 $0.82 per rated watt | 75 $0.71 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% | 90 22.5% module efficiency (from size and rated power) | 38 19.9% module efficiency (from size and rated power) |
| Callsun 450W Bifacial Double-Glass | Callsun 420W (2 x 210W) Bifacial 2-Pack | |
|---|---|---|
| Output | ||
| Rated power | 450 W | 420 W |
| Module efficiency | 22.5% (rated power over panel area) | 19.9% (rated power over panel area) |
| Claimed efficiency | 25.6% (cell efficiency per Callsun's manual and the Amazon listing; Callsun's product page says 25.4%) | 25.6% (cell efficiency; no module efficiency published) |
| Cells | Monocrystalline (N-type, 16BB, 182 mm cells, wired as two parallel halves for shade tolerance) | Monocrystalline (N-type, 16BB, quarter-cut cells, wired as two parallel halves for shade tolerance) |
| Bifacial | Yes | Yes |
| Electrical | ||
| Open-circuit voltage (Voc) | 35.8 V | 40.3 V |
| Voltage at max power (Vmp) | 29.7 V | 34.2 V |
| Short-circuit current (Isc) | 16 A | 6.5 A |
| Current at max power (Imp) | 15.1 A | 6.1 A |
| Voc temperature coefficient | -0.2%/°C | -0.2%/°C |
| Series / parallel | - | Yes |
| Connections | ||
| Output connector | Solar connectors | Solar connectors |
| Build | ||
| Weight | 52.8 lb (24 kg) | - |
| Dimensions | 69.4 x 44.7 x 1.2 in | 54.2 x 30.2 x 1.4 in (each panel) |
| Frame | anodized aluminum alloy | anodized aluminum alloy |
| Glass | double glass: 2.0 mm AR-coated heat-strengthened front, 2.0 mm heat-strengthened back | 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 | 2026-07 | 2026-08 |
