Panasonic EVPV400H vs Heliene 108M10 420W
The Panasonic EVPV400H wins this comparison by a clear margin. It offers better long-term durability with 25-year warranty. For most residential installations, the Panasonic EVPV400H is the stronger choice.
Key Differences
- • Panasonic EVPV400H is rated at 400W while Heliene 108M10 420W is rated at 420W, a 20W difference.
- • Heliene 108M10 420W achieves 21.5% efficiency vs 21.2% for the other, a 0.3 percentage point gap.
- • Both carry matching 25-year product warranties.
- • Panasonic EVPV400H has a superior temperature coefficient of -0.26%/°C vs -0.34%/°C, retaining more power in hot climates.
- • Panasonic EVPV400H uses HJT (Heterojunction) cells while Heliene 108M10 420W uses Mono PERC Half-cut cells, representing different technology generations.
Specifications Breakdown
Module Efficiency
The Heliene 108M10 420W achieves 21.5% module efficiency compared to Panasonic EVPV400H's 21.2%, meaning Heliene 108M10 420W converts 0.3 percentage points more sunlight into electricity per square meter. In practical terms, the Panasonic EVPV400H produces 204.8 watts per square meter of panel area while the Heliene 108M10 420W produces 215.1 W/m². For rooftop installations where space is limited, this efficiency gap determines how many kilowatts you can fit on your available roof area. Over a 25-year system life, even a small efficiency advantage compounds into meaningful additional energy production.
Power Output
The Heliene 108M10 420W delivers 420W per panel versus 400W for the Panasonic EVPV400H, a 20W difference per module. To build an 8 kW residential system, you would need 20 Panasonic EVPV400H panels or 20 Heliene 108M10 420W panels. Despite the per-panel wattage difference, both require the same number of panels for this system size due to rounding. Higher wattage per panel is particularly valuable for commercial-scale installations where panel count directly impacts balance-of-system costs.
Temperature Coefficient
The Panasonic EVPV400H has a temperature coefficient of -0.26%/°C versus -0.34%/°C for the Heliene 108M10 420W. On a hot summer day when cell temperature reaches 65°C (40°C above the 25°C STC baseline), the Panasonic EVPV400H retains 94.8% of its rated power while the other retains 93.2%. This difference is particularly significant in hot climates such as the American Southwest, the Middle East, and Southeast Asia, where panels routinely operate 30-40°C above STC for several hours each day. Over the system lifetime, the cumulative energy advantage from a better temperature coefficient can amount to 2-4% of total production.
Warranty Coverage
The Panasonic EVPV400H is backed by a 25-year product warranty and 25-year performance guarantee, while the Heliene 108M10 420W offers 25-year product and 25-year performance coverage. Both offer identical product warranty duration. Based on their published degradation rates (0.5% first year then 0.35%/year for Panasonic EVPV400H; 1.5% first year then 0.5%/year for Heliene 108M10 420W), after 25 years the Panasonic EVPV400H should retain approximately 91.1% of original output versus 86.5% for the Heliene 108M10 420W. This 4.6 percentage point gap in end-of-life output meaningfully impacts lifetime energy economics.
Physical Dimensions & Weight
The Panasonic EVPV400H measures 1722×1134×30mm and weighs 21 kg, while the Heliene 108M10 420W measures 1722×1134×30mm at 21.5 kg. 1.95 m² of panel area for the Panasonic EVPV400H versus 1.95 m² for the Heliene 108M10 420W. Their weights are closely matched, so neither panel imposes a significantly different structural load on the mounting system. Similar footprints mean both panels fit comparably on standard residential rooftop configurations.
Specification Comparison
| Specification | Panasonic EVPV400H | Heliene 108M10 420W |
|---|---|---|
| Power | 400W | 420W |
| Efficiency | 21.2% | 21.5% |
| Power Density | 19.0 W/sq ft | 20.0 W/sq ft |
| Cell Type | HJT (Heterojunction) | Mono PERC Half-cut |
| Bifacial | Yes | No |
| Weight | 21 kg | 21.5 kg |
| Temp Coefficient | -0.26%/°C | -0.34%/°C |
| Snow Load | 5400 Pa | 5400 Pa |
| Wind Load | 2400 Pa | 2400 Pa |
| Product Warranty | 25 years | 25 years |
| Performance Warranty | 25 years | 25 years |
| Degradation (Year 1) | 0.5% | 1.5% |
| Annual Degradation | 0.35% | 0.5% |
| Country | Japan | Canada |
5-Dimension Head-to-Head Analysis
1. Efficiency & Power Density
Winner: Heliene 108M10 420WThe Heliene 108M10 420W achieves 21.5% efficiency versus 21.2% — a 0.3 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 0.6 kW more total system capacity, or 3 kWh more annual production in an average US location.
2. Hot Climate Performance
Winner: Panasonic EVPV400HThe Panasonic EVPV400H has a better temperature coefficient of -0.26%/°C versus -0.34%/°C. On a 45°C summer day (20°C above STC), the winner retains 94.8% of rated power versus 93.2%. This is a meaningful difference in hot states like Arizona, Texas, and Florida.
3. Durability & Warranty
Winner: Panasonic EVPV400HPanasonic EVPV400H degrades more slowly at 0.35% per year versus 0.5%. After 25 years, expect 91.1% vs 86.5% of original output for Panasonic EVPV400H and Heliene 108M10 420W respectively.
4. Power Output
Winner: Heliene 108M10 420WThe Heliene 108M10 420W delivers 420W versus 400W per panel — 20W more. For an 8 kW system, you need 20 panels with the higher-wattage option versus 20 panels, saving 0 panels and the associated racking and labor costs.
5. Cell Technology
Winner: Panasonic EVPV400HThe Panasonic EVPV400H uses HJT (Heterojunction): HJT (Heterojunction) combines crystalline silicon with amorphous silicon layers, delivering the best temperature coefficient and bifacial gains, but at higher manufacturing cost. The Heliene 108M10 420W uses Mono PERC Half-cut: PERC (Passivated Emitter Rear Cell) is the current mainstream technology, offering good efficiency at the lowest manufacturing cost. HJT (Heterojunction) represents a newer generation technology with a longer performance runway as manufacturing matures.
Panasonic EVPV400H
DISCONTINUED: Panasonic exited solar manufacturing in 2023. The EVPV400H was Panasonic's standard HJT residential panel, delivering 400W with the brand's signature quality and longevity.
Pros
- + Panasonic reliability
- + HJT advantages
- + Solid 25-year warranty
- + Good all-round performer
Cons
- - DISCONTINUED - no longer manufactured
- - No new units available
- - No ongoing product support
Heliene 108M10 420W
The Heliene 108M10 420W is a standard residential-format mono PERC panel manufactured in Heliene's North American facilities (Ontario, Canada and Mountain Iron, Minnesota). The 108 half-cut cell design in the standard 1722 x 1134mm format ensures universal racking compatibility. As one of the few PERC panels made in North America, it offers domestic content ITC bonus eligibility at a more accessible price point than Heliene's HJT line. Backed by Heliene's 25-year product warranty and accessible Canadian/US-based support.
Pros
- + North American manufactured — domestic content ITC bonus eligible
- + Standard 108-cell residential format fits all racking systems
- + More affordable than HJT panels while qualifying for domestic content bonus
- + 25-year product and performance warranties
- + Canadian and US-based customer support
- + 420W competitive output for standard residential size
Cons
- - PERC technology — less efficient than TOPCon/HJT in hot climates
- - -0.34%/°C temp coefficient is standard, not exceptional
- - 420W is competitive but not class-leading
- - Higher cost than Chinese-made PERC panels of similar specs
Choose Panasonic EVPV400H If...
- ✓ You live in a hot climate (Arizona, Texas, Florida) where heat performance matters
- ✓ You want maximum output retention over the system's 25-30 year lifespan
- ✓ You prefer newer cell technology with a longer performance improvement runway
- ✓ No longer available for new installations.
Choose Heliene 108M10 420W If...
- ✓ Your roof space is limited and you need maximum power per panel
- ✓ You want fewer panels to reach your target system size, reducing racking and labor costs
- ✓ Budget-conscious homeowners who want North American-made panels for domestic content ITC bonus without paying the HJT premium.
Our Recommendation
We recommend the Panasonic EVPV400H for most buyers in this comparison. It wins 3 of 5 key dimensions and offers a clear advantage in the metrics that matter most for a solar panel purchase. The Heliene 108M10 420W remains a good product, but the Panasonic EVPV400H delivers better overall value for the majority of installations.
Frequently Asked Questions
Which is better, Panasonic EVPV400H or Heliene 108M10 420W?
The Panasonic EVPV400H wins this comparison by a clear margin. It offers better long-term durability with 25-year warranty. For most residential installations, the Panasonic EVPV400H is the stronger choice.
Which panel is more efficient, Panasonic EVPV400H or Heliene 108M10 420W?
The Heliene 108M10 420W at 21.5% module efficiency. Higher efficiency means more watts per square foot of roof space, which is critical for space-constrained installations. The difference of 0.3 percentage points translates to approximately 20W per panel under standard test conditions.
Which has a better warranty, Panasonic EVPV400H or Heliene 108M10 420W?
The Panasonic EVPV400H comes with a 25-year product warranty and 25-year performance guarantee. The Heliene 108M10 420W offers 25-year product and 25-year performance warranties. Both offer identical warranty terms.
Which panel performs better in hot weather?
The Panasonic EVPV400H has a temperature coefficient of -0.26%/°C and the Heliene 108M10 420W is -0.34%/°C. Panasonic EVPV400H retains more power in heat — important in states like Arizona, Texas, and Florida. A lower (less negative) temperature coefficient is better.
How many Panasonic EVPV400H vs Heliene 108M10 420W panels do I need for an 8 kW system?
For an 8 kW system: you need 20 Panasonic EVPV400H panels (400W each) or 20 Heliene 108M10 420W panels (420W each). The Heliene 108M10 420W requires fewer panels, saving on racking hardware and installation labor.
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Last updated: February 2026