Silfab SIL-370-BK 370W vs GAF Energy Timberline Solar HD
The Silfab SIL-370-BK 370W wins this comparison by a decisive margin. It leads in efficiency (20.4% vs 12%) and matches or exceeds on warranty (25 vs 25 years). For most residential installations, the Silfab SIL-370-BK 370W is the stronger choice.
Key Differences
- • Silfab SIL-370-BK 370W is rated at 370W while GAF Energy Timberline Solar HD is rated at 45W, a 325W difference.
- • Silfab SIL-370-BK 370W achieves 20.4% efficiency vs 12% for the other, a 8.4 percentage point gap.
- • Both carry matching 25-year product warranties.
- • Silfab SIL-370-BK 370W has a superior temperature coefficient of -0.35%/°C vs -0.42%/°C, retaining more power in hot climates.
- • Silfab SIL-370-BK 370W uses PERC Mono cells while GAF Energy Timberline Solar HD uses Monocrystalline cells, representing different technology generations.
Specifications Breakdown
Module Efficiency
The Silfab SIL-370-BK 370W achieves 20.4% module efficiency compared to GAF Energy Timberline Solar HD's 12%, meaning Silfab SIL-370-BK 370W converts 8.4 percentage points more sunlight into electricity per square meter. In practical terms, the Silfab SIL-370-BK 370W produces 189.5 watts per square meter of panel area while the GAF Energy Timberline Solar HD produces 120.2 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 Silfab SIL-370-BK 370W delivers 370W per panel versus 45W for the GAF Energy Timberline Solar HD, a 325W difference per module. To build an 8 kW residential system, you would need 22 Silfab SIL-370-BK 370W panels or 178 GAF Energy Timberline Solar HD panels. Choosing the higher-wattage option saves 156 panels, 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
The Silfab SIL-370-BK 370W has a temperature coefficient of -0.35%/°C versus -0.42%/°C for the GAF Energy Timberline Solar HD. On a hot summer day when cell temperature reaches 65°C (40°C above the 25°C STC baseline), the Silfab SIL-370-BK 370W retains 93.0% of its rated power while the other retains 91.6%. 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 Silfab SIL-370-BK 370W is backed by a 25-year product warranty and 25-year performance guarantee, while the GAF Energy Timberline Solar HD offers 25-year product and 25-year performance coverage. Both offer identical product warranty duration. Based on their published degradation rates (1% first year then 0.4%/year for Silfab SIL-370-BK 370W; 3% first year then 0.65%/year for GAF Energy Timberline Solar HD), after 25 years the Silfab SIL-370-BK 370W should retain approximately 89.4% of original output versus 81.4% for the GAF Energy Timberline Solar HD. This 8.0 percentage point gap in end-of-life output meaningfully impacts lifetime energy economics.
Physical Dimensions & Weight
The Silfab SIL-370-BK 370W measures 1722×1134×30mm and weighs 19.5 kg, while the GAF Energy Timberline Solar HD measures 1070×350×10mm at 4 kg. 1.95 m² of panel area for the Silfab SIL-370-BK 370W versus 0.37 m² for the GAF Energy Timberline Solar HD. The GAF Energy Timberline Solar HD is 15.5 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 310 kg. The more compact GAF Energy Timberline Solar HD may be easier to fit on irregularly shaped or space-limited rooftops.
Specification Comparison
| Specification | Silfab SIL-370-BK 370W | GAF Energy Timberline Solar HD |
|---|---|---|
| Power | 370W | 45W |
| Efficiency | 20.4% | 12% |
| Power Density | 17.6 W/sq ft | 11.2 W/sq ft |
| Cell Type | PERC Mono | Monocrystalline |
| Bifacial | No | No |
| Weight | 19.5 kg | 4 kg |
| Temp Coefficient | -0.35%/°C | -0.42%/°C |
| Snow Load | 2400 Pa | 5400 Pa |
| Wind Load | 2400 Pa | 2400 Pa |
| Product Warranty | 25 years | 25 years |
| Performance Warranty | 25 years | 25 years |
| Degradation (Year 1) | 1% | 3% |
| Annual Degradation | 0.4% | 0.65% |
| Country | United States | United States |
5-Dimension Head-to-Head Analysis
1. Efficiency & Power Density
Winner: Silfab SIL-370-BK 370WThe Silfab SIL-370-BK 370W achieves 20.4% efficiency versus 12% — a 8.4 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 9.8 kW more total system capacity, or 44 kWh more annual production in an average US location.
2. Hot Climate Performance
Winner: Silfab SIL-370-BK 370WThe Silfab SIL-370-BK 370W has a better temperature coefficient of -0.35%/°C versus -0.42%/°C. On a 45°C summer day (20°C above STC), the winner retains 93.0% of rated power versus 91.6%. This is a meaningful difference in hot states like Arizona, Texas, and Florida.
3. Durability & Warranty
Winner: Silfab SIL-370-BK 370WSilfab SIL-370-BK 370W degrades more slowly at 0.4% per year versus 0.65%. After 25 years, expect 89.4% vs 81.4% of original output for Silfab SIL-370-BK 370W and GAF Energy Timberline Solar HD respectively.
4. Power Output
Winner: Silfab SIL-370-BK 370WThe Silfab SIL-370-BK 370W delivers 370W versus 45W per panel — 325W more. For an 8 kW system, you need 22 panels with the higher-wattage option versus 178 panels, saving 156 panels and the associated racking and labor costs.
5. Cell Technology
Winner: GAF Energy Timberline Solar HDThe Silfab SIL-370-BK 370W uses PERC Mono: PERC (Passivated Emitter Rear Cell) is the current mainstream technology, offering good efficiency at the lowest manufacturing cost. The GAF Energy Timberline Solar HD uses Monocrystalline: Monocrystalline. Monocrystalline represents a newer generation technology with a longer performance runway as manufacturing matures.
Silfab SIL-370-BK 370W
The SIL-370-BK is Silfab's entry-level US-made all-black panel delivering 370W for budget-conscious domestic installations.
Pros
- + Made in USA
- + All-black design
- + 25-year warranty
- + ARRA compliant
Cons
- - Lower wattage
- - Basic PERC technology
- - Less competitive efficiency
GAF Energy Timberline Solar HD
The GAF Energy Timberline Solar HD is the earlier-generation nailable solar shingle from GAF Energy, delivering 45W per shingle at approximately 12% efficiency. Like the newer ES model, it installs with a nail gun alongside standard GAF Timberline HD architectural shingles. Installed cost is $4.50-$6.00/W.
Pros
- + Nailable installation — standard roofing tools
- + 25-year warranty
- + Class A fire rating
- + Low-profile aesthetic integration with GAF roofing
- + Backed by GAF — North America's largest roofing manufacturer
Cons
- - Only 45W per shingle — requires many units
- - 12% efficiency significantly below modern panels and newer ES model
- - $4.50-$6.00/W installed — highest cost per watt in BIPV category
- - Older generation superseded by ES model
- - Higher degradation rate than newer products
Choose Silfab SIL-370-BK 370W 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
- ✓ 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
- ✓ Government or institutional projects requiring ARRA/Buy America compliance.
Choose GAF Energy Timberline Solar HD If...
- ✓ Homeowners in areas where only the HD model is available, or existing Timberline HD roof owners seeking a matching solar upgrade.
Our Recommendation
The Silfab SIL-370-BK 370W is the decisive winner in this solar panel comparison, outperforming the GAF Energy Timberline Solar HD in 4 of 5 dimensions. Unless you have a specific requirement that the GAF Energy Timberline Solar HD uniquely addresses, the Silfab SIL-370-BK 370W is the stronger choice for virtually every installation scenario.
Frequently Asked Questions
Which is better, Silfab SIL-370-BK 370W or GAF Energy Timberline Solar HD?
The Silfab SIL-370-BK 370W wins this comparison by a decisive margin. It leads in efficiency (20.4% vs 12%) and matches or exceeds on warranty (25 vs 25 years). For most residential installations, the Silfab SIL-370-BK 370W is the stronger choice.
Which panel is more efficient, Silfab SIL-370-BK 370W or GAF Energy Timberline Solar HD?
The Silfab SIL-370-BK 370W at 20.4% module efficiency. Higher efficiency means more watts per square foot of roof space, which is critical for space-constrained installations. The difference of 8.4 percentage points translates to approximately 325W per panel under standard test conditions.
Which has a better warranty, Silfab SIL-370-BK 370W or GAF Energy Timberline Solar HD?
The Silfab SIL-370-BK 370W comes with a 25-year product warranty and 25-year performance guarantee. The GAF Energy Timberline Solar HD offers 25-year product and 25-year performance warranties. Both offer identical warranty terms.
Which panel performs better in hot weather?
The Silfab SIL-370-BK 370W has a temperature coefficient of -0.35%/°C and the GAF Energy Timberline Solar HD is -0.42%/°C. Silfab SIL-370-BK 370W retains more power in heat — important in states like Arizona, Texas, and Florida. A lower (less negative) temperature coefficient is better.
How many Silfab SIL-370-BK 370W vs GAF Energy Timberline Solar HD panels do I need for an 8 kW system?
For an 8 kW system: you need 22 Silfab SIL-370-BK 370W panels (370W each) or 178 GAF Energy Timberline Solar HD panels (45W each). The Silfab SIL-370-BK 370W requires fewer panels, saving on racking hardware and installation labor.
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Last updated: February 2026