---
title: "JA Solar JAM66D46-735/LB vs JA Solar JAM78D40-615/MB/1500V - Solar Panel Comparison | ComparePV"
description: "Compare JA Solar JAM66D46-735/LB vs JA Solar JAM78D40-615/MB/1500V side by side: what actually differs, output when it is hot, thirty-year production, and the full specification."
source: "https://comparepv.com/compare/ja-solar-jam66d46-735-lb/ja-solar-jam78d40-615-mb-1500v"
updated: 2026-09-11
---

# JA Solar JAM66D46-735/LB vs JA Solar JAM78D40-615/MB/1500V

JAM66D46-735/LB leads on the differences that matter

The largest is module efficiency: 1.70 pp more efficient. 5 of 19 comparable parameters are identical.


## The two panels


| Attribute | A | B |
| --- | --- | --- |
| Panel | [JA Solar JAM66D46-735/LB](https://comparepv.com/panel/ja-solar-jam66d46-735-lb) | [JA Solar JAM78D40-615/MB/1500V](https://comparepv.com/panel/ja-solar-jam78d40-615-mb-1500v) |
| Manufacturer | JA Solar | JA Solar |
| Power | 735 Wp | 615 Wp |
| Efficiency | 23.70 % | 22.00 % |
| Technology | TOPCon | N-type |


## Where they differ

Ranked by how much the difference matters, not by datasheet order.


| Parameter | JAM66D46-735/LB | JAM78D40-615/MB/1500V | Difference |
| --- | --- | --- | --- |
| Module efficiency | 23.70 % | 22.00 % | +1.70 pp for JAM66D46-735/LB |
| Rated power | 735 Wp | 615 Wp | +120 W for JAM66D46-735/LB |
| Power density | 236.6 Wp/m² | 220.0 Wp/m² | +16.6 Wp/m² for JAM66D46-735/LB |
| Weight | 38.2 kg | 34.6 kg | -3.6 kg for JAM78D40-615/MB/1500V |
| Open-circuit voltage | 49.60 V | 55.20 V | 5.60 V apart |
| Short-circuit current | 18.70 A | 14.23 A | 4.47 A apart |
| Module area | 3.106 m² | 2.795 m² | 0.311 m² apart |
| Weight per kWp | 52.0 kg/kWp | 56.3 kg/kWp | -4.3 kg/kWp for JAM66D46-735/LB |
| Temperature coefficient | -0.290 %/°C | -0.300 %/°C | +0.010 %/°C for JAM66D46-735/LB |
| Cell technology | TOPCon | N-type | TOPCon vs N-type |
| Voltage at max power | 41.77 V | 46.07 V | 4.30 V apart |
| Current at max power | 17.60 A | 13.35 A | 4.25 A apart |
| Cell count | 132 | 156 | 24 cells apart |
| Dimensions | 2384x1303x33 mm | 2465x1134x35 mm | 2384x1303x33 mm vs 2465x1134x35 mm |


## Every compared parameter


| Parameter | JAM66D46-735/LB | JAM78D40-615/MB/1500V |
| --- | --- | --- |
| Rated power | 735 Wp | 615 Wp |
| Module efficiency | 23.70 % | 22.00 % |
| Power density | 236.6 Wp/m² | 220.0 Wp/m² |
| Open-circuit voltage | 49.60 V | 55.20 V |
| Voltage at max power | 41.77 V | 46.07 V |
| Short-circuit current | 18.70 A | 14.23 A |
| Current at max power | 17.60 A | 13.35 A |
| Temperature coefficient | -0.290 %/°C | -0.300 %/°C |
| Dimensions | 2384x1303x33 mm | 2465x1134x35 mm |
| Module area | 3.106 m² | 2.795 m² |
| Weight | 38.2 kg | 34.6 kg |
| Weight per kWp | 52.0 kg/kWp | 56.3 kg/kWp |
| Product warranty | 12 yrs | 12 yrs |
| Performance warranty | 30 yrs | 30 yrs |
| Annual degradation | 0.40 %/yr | 0.40 %/yr |
| Cell technology | TOPCon | N-type |
| Cell type | Monocrystalline | Monocrystalline |
| Cell count | 132 | 156 |
| Bifacial | Yes | Yes |


## Thirty-year yield

Each panel's own declared degradation curve, at 1,200 kWh/kWp a year

- **Cumulative output, JAM66D46-735/LB:** 24,661 kWh
- **Cumulative output, JAM78D40-615/MB/1500V:** 20,634 kWh
- **Gap:** 4,027 kWh


## Output when hot


| Condition | Cell temperature | JAM66D46-735/LB | JAM78D40-615/MB/1500V | Retained |
| --- | --- | --- | --- | --- |
| Standard test conditions | 25 °C | 735 W | 615 W | 100.0% of rated power |
| Cool, bright day | 40 °C | 703 W | 587 W | 95.5% of rated power |
| Typical summer roof | 55 °C | 671 W | 560 W | 91.0% of rated power |
| Hot roof | 70 °C | 639 W | 532 W | 86.5% of rated power |


## Against the whole database


| Measure | JAM66D46-735/LB | JAM78D40-615/MB/1500V | Out of | Note |
| --- | --- | --- | --- | --- |
| Efficiency | #517 | #6,517 | 14,005 | JAM66D46-735/LB leads by 6,000 places |
| Power density | #582 | #6,655 | 14,005 | JAM66D46-735/LB leads by 6,073 places |
| Heat behaviour | #2,165 | #6,093 | 14,005 | JAM66D46-735/LB leads by 3,928 places |
| Weight | #5,413 | #10,534 | 14,005 | JAM66D46-735/LB leads by 5,121 places |
| Warranty | #21 | #21 | 14,005 | Tied - the same position in the database |
| Overall | #233 | #3,865 | 14,005 | JAM66D46-735/LB leads by 3,632 places |


## Questions


### Which panel is better: JA Solar JAM66D46-735/LB or JA Solar JAM78D40-615/MB/1500V?

According to our database: **JA Solar JAM66D46-735/LB** has higher module efficiency (**23.70%** vs **22.00%**); **JA Solar JAM66D46-735/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 JAM66D46-735/LB and JA Solar JAM78D40-615/MB/1500V?

**JA Solar JAM66D46-735/LB** has a module efficiency of **23.70%**, while **JA Solar JAM78D40-615/MB/1500V** is **22.00%**. Higher efficiency means more electricity from the same roof area - useful when space is limited.


### What cell technology does JA Solar JAM66D46-735/LB use vs JA Solar JAM78D40-615/MB/1500V?

**JA Solar JAM66D46-735/LB** uses **TOPCon** cells; **JA Solar JAM78D40-615/MB/1500V** uses **N-type**. 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 JAM66D46-735/LB and JA Solar JAM78D40-615/MB/1500V?

**JA Solar JAM66D46-735/LB** has a **30 years** power warranty; **JA Solar JAM78D40-615/MB/1500V** 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 JAM66D46-735/LB and JA Solar JAM78D40-615/MB/1500V bifacial panels?

Both **JA Solar JAM66D46-735/LB** and **JA Solar JAM78D40-615/MB/1500V** 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.


## Related comparisons

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- [JA Solar JAM66D46-735/LB vs JA Solar JAM66D46-730/LB](https://comparepv.com/compare/ja-solar-jam66d46-735-lb/ja-solar-jam66d46-730-lb) - One difference: module efficiency
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- [JA Solar JAM66D46-735/LB vs JA Solar JAM66D46-715/LB](https://comparepv.com/compare/ja-solar-jam66d46-735-lb/ja-solar-jam66d46-715-lb) - 3 differences, the largest is module efficiency
- [JA Solar JAM66D46-735/LB vs JA Solar JAM66D46-710/LB](https://comparepv.com/compare/ja-solar-jam66d46-735-lb/ja-solar-jam66d46-710-lb) - 5 differences, the largest is module efficiency


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Source: https://comparepv.com/compare/ja-solar-jam66d46-735-lb/ja-solar-jam78d40-615-mb-1500v

Not in this file, on the page: the thirty-year yield curve year by year at a cell temperature you pick and a written summary generated on request.