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JAM78D40-620/MB/1500V vs JAM66D46-740/LB 5 of 19 identical Swap Change panels

JA Solar JAM78D40-620/MB/1500V vs JA Solar JAM66D46-740/LB

JAM78D40-620/MB/1500V
620 Wp 22.20 % N-type Bifacial
Open panel page Datasheet PDF
VS
JA Solar JAM66D46-740/LB
JAM66D46-740/LB
740 Wp 23.80 % TOPCon Bifacial
Open panel page Datasheet PDF
The verdict

JAM66D46-740/LB leads on the differences that matter

The largest is module efficiency: 1.60 pp more efficient. 5 of 19 comparable parameters are identical.

See all 14 differences
How alike are they
5 of 19 comparable
parameters are identical
identical differs
01

What actually differs

14 of 19 parameters
Parameter JAM78D40-620/MB/1500V JAM66D46-740/LB Difference
Module efficiency 22.20 % 23.80 % 1.60 pp more efficient
Rated power 620 Wp 740 Wp 120 W more power
Power density 221.8 Wp/m² 238.2 Wp/m² 16.4 Wp/m² higher
Weight 34.6 kg 38.2 kg 3.6 kg lighter
Open-circuit voltage 55.34 V 49.80 V 5.54 V apart
Short-circuit current 14.30 A 18.73 A 4.43 A apart
Module area 2.795 m² 3.106 m² 0.311 m² apart
Weight per kWp 55.8 kg/kWp 51.6 kg/kWp 4.2 kg/kWp lighter
Temperature coefficient -0.300 %/°C -0.290 %/°C 0.010 %/°C better in heat
Cell technology N-type TOPCon N-type vs TOPCon
Voltage at max power 46.20 V 41.96 V 4.24 V apart
Current at max power 13.42 A 17.64 A 4.22 A apart
Cell count 156 132 24 cells apart
Dimensions 2465x1134x35 mm 2384x1303x33 mm 2465x1134x35 mm vs 2384x1303x33 mm
02

What it means on a roof

Thirty years of production
Each panel's own declared degradation curve, at 1,200 kWh/kWp a year
JAM78D40-620/MB/1500V
20,802 kWh
JAM66D46-740/LB
24,828 kWh
Lifetime gap
4,026 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario JAM78D40-620/MB/1500V JAM66D46-740/LB
Standard test conditions 25 °C 100.0% of rated power 620 W 740 W
Cool, bright day 40 °C 95.5% of rated power 592 W 708 W
Typical summer roof 55 °C 91.0% of rated power 564 W 676 W
Hot roof 70 °C 86.5% of rated power 536 W 643 W
03

Full specification

Parameter JAM78D40-620/MB/1500V JAM66D46-740/LB Difference
Power and efficiency
Rated power 620 Wp 740 Wp +120 W for JAM66D46-740/LB
Module efficiency 22.20 % 23.80 % +1.60 pp for JAM66D46-740/LB
Power density 221.8 Wp/m² 238.2 Wp/m² +16.4 Wp/m² for JAM66D46-740/LB
Open-circuit voltage 55.34 V 49.80 V 5.54 V apart
Voltage at max power 46.20 V 41.96 V 4.24 V apart
Short-circuit current 14.30 A 18.73 A 4.43 A apart
Current at max power 13.42 A 17.64 A 4.22 A apart
Temperature
Temperature coefficient -0.300 %/°C -0.290 %/°C +0.010 %/°C for JAM66D46-740/LB
Mechanical
Dimensions 2465x1134x35 mm 2384x1303x33 mm 2465x1134x35 mm vs 2384x1303x33 mm
Module area 2.795 m² 3.106 m² 0.311 m² apart
Weight 34.6 kg 38.2 kg -3.6 kg for JAM78D40-620/MB/1500V
Weight per kWp 55.8 kg/kWp 51.6 kg/kWp -4.2 kg/kWp for JAM66D46-740/LB
Warranty and degradation
Product warranty 12 yrs 12 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.40 %/yr 0.40 %/yr Same
Technology
Cell technology N-type TOPCon N-type vs TOPCon
Cell type Monocrystalline Monocrystalline Same
Cell count 156 132 24 cells apart
Bifacial Yes Yes Same
04

Against the whole database

14,005 panels
Efficiency
#5,817 vs #433
JAM66D46-740/LB leads by 5,384 places
Power density
#5,869 vs #431
JAM66D46-740/LB leads by 5,438 places
Heat behaviour
#6,093 vs #2,165
JAM66D46-740/LB leads by 3,928 places
Weight
#10,192 vs #4,997
JAM66D46-740/LB leads by 5,195 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#3,457 vs #185
JAM66D46-740/LB leads by 3,272 places
05

More useful comparisons

Open the full database
Same series, other bin
JA Solar JAM78D40-620/MB/1500V vs JA Solar JAM78D40-625/MB/1500V
One difference: module efficiency
Same series, other bin
JA Solar JAM78D40-620/MB/1500V vs JA Solar JAM78D40-615/MB/1500V
One difference: module efficiency
Same series, other bin
JA Solar JAM78D40-620/MB/1500V vs JA Solar JAM78D40-610/MB/1500V
3 differences, the largest is module efficiency
Same series, other bin
JA Solar JAM78D40-620/MB/1500V vs JA Solar JAM78D40-605/MB/1500V
3 differences, the largest is module efficiency
Same series, other bin
JA Solar JAM78D40-620/MB/1500V vs JA Solar JAM78D40-600/MB/1500V
3 differences, the largest is module efficiency
Same series, other bin
JA Solar JAM66D46-740/LB vs JA Solar JAM66D46-735/LB
The same specification on paper
06

Written summary

07

Questions about this pairing

Which panel is better: JA Solar JAM78D40-620/MB/1500V or JA Solar JAM66D46-740/LB?
According to our database: JA Solar JAM66D46-740/LB has higher module efficiency (23.80% vs 22.20%); JA Solar JAM66D46-740/LB tolerates heat better (temp coeff -0.290%/°C vs -0.300%/°C). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of JA Solar JAM78D40-620/MB/1500V and JA Solar JAM66D46-740/LB?
JA Solar JAM78D40-620/MB/1500V has a module efficiency of 22.20%, while JA Solar JAM66D46-740/LB is 23.80%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does JA Solar JAM78D40-620/MB/1500V use vs JA Solar JAM66D46-740/LB?
JA Solar JAM78D40-620/MB/1500V uses N-type cells; JA Solar JAM66D46-740/LB uses TOPCon. Modern n-type technologies (TOPCon, HJT, BC) typically deliver higher efficiency and lower degradation compared to older PERC (p-type) cells.
What is the warranty on JA Solar JAM78D40-620/MB/1500V and JA Solar JAM66D46-740/LB?
JA Solar JAM78D40-620/MB/1500V has a 30 years power warranty; JA Solar JAM66D46-740/LB has a 30 years power warranty. The power warranty guarantees a minimum percentage of rated output at the end of the warranty period (typically 80-87%). Product (materials) warranties are usually shorter.
Are JA Solar JAM78D40-620/MB/1500V and JA Solar JAM66D46-740/LB bifacial panels?
Both JA Solar JAM78D40-620/MB/1500V and JA Solar JAM66D46-740/LB are bifacial - they capture reflected light from the ground, which can add 5-15% more annual energy on ground-mount or elevated rooftop installations with a light surface beneath.

Shop prices: See 393 JA Solar offers

Every figure here is from the manufacturers' own datasheets - a dash means the value is not published, never an estimate. The thirty-year projection and the temperature scenarios are calculations from those figures, and each states its assumption above.