LONGi Hi-MO 7 590W vs First Solar Series 7 545W
The LONGi Hi-MO 7 590W wins this comparison by a decisive margin. It leads in efficiency (22.8% vs 19.8%) and matches or exceeds on warranty (12 vs 10 years). For most residential installations, the LONGi Hi-MO 7 590W is the stronger choice.
Key Differences
- • LONGi Hi-MO 7 590W is rated at 590W while First Solar Series 7 545W is rated at 545W, a 45W difference.
- • LONGi Hi-MO 7 590W achieves 22.8% efficiency vs 19.8% for the other, a 3.0 percentage point gap.
- • LONGi Hi-MO 7 590W comes with a 12-year product warranty vs 10 years for the other.
- • LONGi Hi-MO 7 590W uses HPBC (Back Contact N-type) cells while First Solar Series 7 545W uses CdTe (Cadmium Telluride) cells, representing different technology generations.
Specifications Breakdown
Module Efficiency
The LONGi Hi-MO 7 590W achieves 22.8% module efficiency compared to First Solar Series 7 545W's 19.8%, meaning LONGi Hi-MO 7 590W converts 3.0 percentage points more sunlight into electricity per square meter. In practical terms, the LONGi Hi-MO 7 590W produces 228.4 watts per square meter of panel area while the First Solar Series 7 545W produces 173.9 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 LONGi Hi-MO 7 590W delivers 590W per panel versus 545W for the First Solar Series 7 545W, a 45W difference per module. To build an 8 kW residential system, you would need 14 LONGi Hi-MO 7 590W panels or 15 First Solar Series 7 545W panels. Choosing the higher-wattage option saves 1 panel, reducing total racking hardware, wiring, and installation labor costs. Higher wattage per panel is particularly valuable for commercial-scale installations where panel count directly impacts balance-of-system costs.
Temperature Coefficient
Both panels share an identical temperature coefficient of -0.28%/°C, meaning they lose power at the same rate as cell temperature rises above the 25°C standard test baseline. At 65°C cell temperature, both retain 94.4% of rated power. Neither panel has a thermal performance advantage, which makes this specification a non-factor in the comparison.
Warranty Coverage
The LONGi Hi-MO 7 590W is backed by a 12-year product warranty and 30-year performance guarantee, while the First Solar Series 7 545W offers 10-year product and 30-year performance coverage. The LONGi Hi-MO 7 590W provides 2 additional years of defect protection, covering manufacturing issues, material failures, and premature performance loss. Based on their published degradation rates (1% first year then 0.4%/year for LONGi Hi-MO 7 590W; 1.5% first year then 0.5%/year for First Solar Series 7 545W), after 25 years the LONGi Hi-MO 7 590W should retain approximately 89.4% of original output versus 86.5% for the First Solar Series 7 545W. This 2.9 percentage point gap in end-of-life output meaningfully impacts lifetime energy economics.
Physical Dimensions & Weight
The LONGi Hi-MO 7 590W measures 2278×1134×35mm and weighs 28.8 kg, while the First Solar Series 7 545W measures 2520×1244×49mm at 38 kg. 2.58 m² of panel area for the LONGi Hi-MO 7 590W versus 3.13 m² for the First Solar Series 7 545W. The LONGi Hi-MO 7 590W is 9.2 kg lighter per panel, which reduces structural load requirements on the roof and makes handling easier during installation. For a 20-panel system, that is a total weight difference of 184 kg. The more compact LONGi Hi-MO 7 590W may be easier to fit on irregularly shaped or space-limited rooftops.
Specification Comparison
| Specification | LONGi Hi-MO 7 590W | First Solar Series 7 545W |
|---|---|---|
| Power | 590W | 545W |
| Efficiency | 22.8% | 19.8% |
| Power Density | 21.2 W/sq ft | 16.2 W/sq ft |
| Cell Type | HPBC (Back Contact N-type) | CdTe (Cadmium Telluride) |
| Bifacial | Yes | No |
| Weight | 28.8 kg | 38 kg |
| Temp Coefficient | -0.28%/°C | -0.28%/°C |
| Snow Load | 5400 Pa | 5400 Pa |
| Wind Load | 2400 Pa | 4000 Pa |
| Product Warranty | 12 years | 10 years |
| Performance Warranty | 30 years | 30 years |
| Degradation (Year 1) | 1% | 1.5% |
| Annual Degradation | 0.4% | 0.5% |
| Country | China | United States |
5-Dimension Head-to-Head Analysis
1. Efficiency & Power Density
Winner: LONGi Hi-MO 7 590WThe LONGi Hi-MO 7 590W achieves 22.8% efficiency versus 19.8% — a 3.0 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 1.4 kW more total system capacity, or 7 kWh more annual production in an average US location.
2. Hot Climate Performance
Winner: TieBoth panels share a temperature coefficient of -0.28%/°C — identical heat tolerance.
3. Durability & Warranty
Winner: LONGi Hi-MO 7 590WLONGi Hi-MO 7 590W leads with a 12-year product warranty versus 10 years. LONGi Hi-MO 7 590W degrades more slowly at 0.4% per year versus 0.5%. After 25 years, expect 89.4% vs 86.5% of original output for LONGi Hi-MO 7 590W and First Solar Series 7 545W respectively.
4. Power Output
Winner: LONGi Hi-MO 7 590WThe LONGi Hi-MO 7 590W delivers 590W versus 545W per panel — 45W more. For an 8 kW system, you need 14 panels with the higher-wattage option versus 15 panels, saving 1 panels and the associated racking and labor costs.
5. Cell Technology
Winner: LONGi Hi-MO 7 590WThe LONGi Hi-MO 7 590W uses HPBC (Back Contact N-type): HPBC (Hybrid Passivated Back Contact) is a proprietary LONGi architecture combining back-contact design with advanced passivation for both high efficiency and aesthetic uniformity. The First Solar Series 7 545W uses CdTe (Cadmium Telluride): CdTe (Cadmium Telluride). HPBC (Back Contact N-type) represents a newer generation technology with a longer performance runway as manufacturing matures.
LONGi Hi-MO 7 590W
The Hi-MO 7 is LONGi's flagship residential panel using proprietary HPBC (Hybrid Passivated Back Contact) cell technology for exceptional 22.8% efficiency and 590W output.
Pros
- + Industry-leading HPBC back-contact technology
- + 22.8% efficiency
- + Excellent temperature coefficient
- + Lower degradation rate
Cons
- - Premium pricing
- - Heavy at 28.8 kg
- - New technology with limited track record
First Solar Series 7 545W
First Solar Series 7 is a US-made thin-film CdTe module delivering 545W with superior temperature performance and sustainable manufacturing.
Pros
- + US manufactured thin-film
- + Excellent hot weather performance
- + Lower carbon footprint
- + No supply chain issues
Cons
- - Lower efficiency than crystalline silicon
- - Very large and heavy
- - Not for residential roofs
Choose LONGi Hi-MO 7 590W 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
- ✓ Long-term warranty protection is a top priority and you plan to stay in your home for 12+ years
- ✓ You want maximum output retention over the system's 25-30 year lifespan
- ✓ Premium residential installations seeking maximum efficiency.
Choose First Solar Series 7 545W If...
- ✓ Utility-scale projects valuing US manufacturing and hot-climate performance.
Our Recommendation
The LONGi Hi-MO 7 590W is the decisive winner in this solar panel comparison, outperforming the First Solar Series 7 545W in 4 of 5 dimensions. Unless you have a specific requirement that the First Solar Series 7 545W uniquely addresses, the LONGi Hi-MO 7 590W is the stronger choice for virtually every installation scenario.
Frequently Asked Questions
Which is better, LONGi Hi-MO 7 590W or First Solar Series 7 545W?
The LONGi Hi-MO 7 590W wins this comparison by a decisive margin. It leads in efficiency (22.8% vs 19.8%) and matches or exceeds on warranty (12 vs 10 years). For most residential installations, the LONGi Hi-MO 7 590W is the stronger choice.
Which panel is more efficient, LONGi Hi-MO 7 590W or First Solar Series 7 545W?
The LONGi Hi-MO 7 590W at 22.8% module efficiency. Higher efficiency means more watts per square foot of roof space, which is critical for space-constrained installations. The difference of 3.0 percentage points translates to approximately 45W per panel under standard test conditions.
Which has a better warranty, LONGi Hi-MO 7 590W or First Solar Series 7 545W?
The LONGi Hi-MO 7 590W comes with a 12-year product warranty and 30-year performance guarantee. The First Solar Series 7 545W offers 10-year product and 30-year performance warranties. LONGi Hi-MO 7 590W provides 2 additional years of product coverage.
Which panel performs better in hot weather?
The LONGi Hi-MO 7 590W has a temperature coefficient of -0.28%/°C and the First Solar Series 7 545W is -0.28%/°C. Both handle heat equally. A lower (less negative) temperature coefficient is better.
How many LONGi Hi-MO 7 590W vs First Solar Series 7 545W panels do I need for an 8 kW system?
For an 8 kW system: you need 14 LONGi Hi-MO 7 590W panels (590W each) or 15 First Solar Series 7 545W panels (545W each). The LONGi Hi-MO 7 590W requires fewer panels, saving on racking hardware and installation labor.
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Last updated: February 2026