The Renogy 640W (2 x 320W) Bifacial 2-Pack is the better rigid solar panel overall, rated 3.9 to 3.8. The DOKIO 800W (2 x 400W) 2-Pack wins on value and efficiency. The Renogy 640W (2 x 320W) Bifacial 2-Pack costs $2.43 less ($487.34 vs $489.77).
A low-cost bifacial pair for a ground mount or shed roof over light gravel or concrete, where the back side can earn its keep. On a dark roof, Renogy’s N-type 320 W pair is the better panel.
Amazon $487.34A low-cost way to put 800 W on a shed roof or ground mount with an MPPT controller. Buyers who want a stated warranty and a full spec sheet should pay a little more for a better-documented brand.
Amazon $489.77Prices 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 | Renogy 640W (2 x 320W) Bifacial 2-Pack | DOKIO 800W (2 x 400W) 2-Pack |
|---|---|---|
| Overall rating | 3.9/5 | 3.8/5 |
| Value 45% | 70 $0.76 per rated watt | 85 $0.61 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 | 50 IP rating and warranty not published (neutral score used) |
| Efficiency 15% | 24 19.2% module efficiency | 50 20.5% module efficiency (from size and rated power) |
| Renogy 640W (2 x 320W) Bifacial 2-Pack | DOKIO 800W (2 x 400W) 2-Pack | |
|---|---|---|
| Output | ||
| Rated power | 640 W | 800 W |
| Module efficiency | 19.2% | 20.5% (rated power over panel area) |
| Claimed efficiency | 19.2% (module efficiency from the datasheet; no cell efficiency published) | - |
| Cells | Monocrystalline (PERC, 10BB, half-cut, 90 cells (per the Amazon listing and datasheet)) | Monocrystalline |
| Bifacial | Yes | No |
| Electrical | ||
| Open-circuit voltage (Voc) | 30.4 V | 37.1 V |
| Voltage at max power (Vmp) | 26.1 V | 31 V |
| Short-circuit current (Isc) | 13.1 A | 13.2 A |
| Current at max power (Imp) | 12.3 A | - |
| Voc temperature coefficient | -0.3%/°C | - |
| Series / parallel | Yes | Yes |
| Connections | ||
| Output connector | Solar connectors (IP68) | MC4 |
| Build | ||
| Dimensions | 67.9 x 38.0 x 1.4 in (each panel) | 67.8 x 44.6 x 1.2 in (each panel) |
| Frame | anodized aluminum alloy | aluminum |
| Glass | 3.2 mm tempered | tempered |
| Junction box rating | IP68 | - |
| Warranty | 10 years | - |
| Output warranty | 25-year power output warranty | - |
| Released | 2025-07 | - |
