REC TwinPeak 5 420W Specifications & Review
The REC TwinPeak 5 delivers 420W using proven PERC technology with REC's signature half-cut cell design and 20-year product warranty.
What Makes the REC TwinPeak 5 420W Different
The REC TwinPeak 5 420W is part of REC's premium TwinPeak series, manufactured in Singapore with some of the most stringent quality controls in the solar industry. REC is renowned for manufacturing excellence — their panels consistently rank at the top of independent quality testing by PVEL and TUV. At 420W and 21.4% efficiency using PERC Mono cells, the TwinPeak 5 420W delivers premium performance. REC's industry-leading 20-year product warranty and 25-year performance warranty with just 0.4% annual degradation reflect their confidence in build quality. The 1722×1134mm format at 21 kg fits standard residential racking.
Key Specifications
| Brand | REC |
| Model | REC TwinPeak 5 420W |
| Power Output | 420W |
| Efficiency | 21.4% |
| Power Density | 20.0 W/sq ft |
| Cell Type | PERC Mono |
| Cell Count | 108 cells |
| Dimensions | 1722 x 1134 x 30 mm |
| Weight | 21 kg |
| Open Circuit Voltage (Voc) | 40.5V |
| Max Power Voltage (Vmp) | 33.8V |
| Short Circuit Current (Isc) | 13.42A |
| Max Power Current (Imp) | 12.43A |
| Temp Coefficient (Pmax) | -0.32%/°C |
| Product Warranty | 20 years |
| Performance Warranty | 25 years |
| First Year Degradation | 1% |
| Annual Degradation | 0.4% |
| Country of Manufacture | Singapore |
| Certifications | IEC 61215, IEC 61730, UL 1703, MCS |
| Snow Load | 5400 Pa (112.8 psf) — Heavy Snow Rated |
| Wind Load | 3600 Pa (75.2 psf) |
Pros & Cons
Pros
- ✓ Strong 20-year product warranty
- ✓ Good shade tolerance
- ✓ Proven half-cut design
- ✓ European engineering
Cons
- ✗ Lower efficiency vs HJT models
- ✗ PERC limitations
- ✗ Premium vs Chinese brands
Best For
Homeowners wanting European-quality PERC panels with a strong warranty.
Is the REC TwinPeak 5 420W Worth It?
The REC TwinPeak 5 420W delivers 420W of power at 21.4% module efficiency, which is above the current industry average of approximately 21%. This higher efficiency means you need fewer panels to reach your target system size, saving roof space and potentially reducing mounting hardware costs.
From a warranty perspective, the TwinPeak 5 420W comes with a solid 20-year product warranty and a 25-year performance guarantee. The industry standard for product warranties ranges from 12 to 25 years, so this panel offers solid coverage that meets or exceeds the industry midpoint. At the end of 25 years, the panel is guaranteed to still produce approximately 89.4% of its rated output, with first-year degradation of 1% and just 0.4% per year after that.
Pricing varies by region and installer, but the TwinPeak 5 420W's combination of 21.4% efficiency and 20-year warranty should be weighed against per-watt quotes from your installer. Request at least three quotes to ensure you are getting competitive pricing for this tier of panel.
For hot climates, the temperature coefficient of -0.32%/°C is good. This falls within the typical range, so you can expect reasonable performance in most climates, though premium panels with coefficients closer to -0.25%/°C will edge ahead in extreme heat. Overall, the REC TwinPeak 5 420W represents a strong value proposition for most residential installations.
Real-World Performance
In real-world conditions, the REC TwinPeak 5 420W delivers consistent energy production shaped by its -0.32%/°C temperature coefficient. On a hot summer day when panel surface temperatures reach 65°C (40°C above STC), the TwinPeak 5 420W loses approximately 12.8% of rated output — typical for PERC technology. Over a full year in a typical US location, expect annual specific yield of 1,400-1,700 kWh per kW installed, depending on location, tilt, and shading. The 1% first-year degradation settles into 0.4% annual degradation thereafter; after 25 years the TwinPeak 5 420W should still produce approximately 89.4% of its original rating. The 108 half-cut cells provide improved shade tolerance compared to full-cell designs — when one cell is shaded, only one sub-string is affected rather than an entire string, limiting production losses to approximately one-third of the panel rather than one-half.
Who Should Buy the REC TwinPeak 5 420W?
System Design Tips
For string inverter systems, the REC TwinPeak 5 420W's Voc of 40.5V allows up to 14 panels per string on a 600V inverter, or 11 panels per string on 480V systems. The Isc of 13.42A is within the input range of all major residential string inverters and microinverters. For microinverter pairing, the Enphase IQ8A (366VA) or IQ8H (384VA) handles the 420W output well with a DC/AC ratio of 1.1-1.1. SolarEdge P505 optimizers pair well for optimizer-based systems. Size your inverter at 75-90% of total DC wattage for optimal clipping management — for a 24-panel array (10.1 kW DC), a 8 W AC inverter is a good match. The panel handles 5400 Pa snow load and 3600 Pa wind load.
Price Estimate
The REC TwinPeak 5 420W is sold through residential solar distributors and installers. REC pricing varies by distributor and order volume. For a 24-panel system (10.1 kW DC), total installed cost including panels, inverter, racking, wiring, permitting, and labor typically runs $2.50-3.50/W, or approximately $30,240-$35,280 before the 30% federal ITC. After ITC: approximately $21,168-$24,696.
How the REC TwinPeak 5 420W Compares
| Model | Wattage | Efficiency | W/sq ft | Warranty | Snow Load | Cell Type |
|---|---|---|---|---|---|---|
| REC TwinPeak 5 420W (this panel) | 420W | 21.4% | 20.0 | 20 yrs | 5400 Pa | PERC Mono |
| Trina Solar Vertex S 420W | 420W | 21.3% | 19.5 | 15 yrs | 5400 Pa | PERC Mono |
| Canadian Solar CS6R 420W | 420W | 21% | 20.0 | 12 yrs | 5400 Pa | PERC Mono |
| Q CELLS Q.TRON BLK M-G11+ 420W | 420W | 21.6% | 20.0 | 25 yrs | 5400 Pa | TOPCon N-type |
Compare This Panel
Installation & Compatibility
System Voltage & String Sizing
- Open Circuit Voltage (Voc)
- 40.5V
- Max Power Voltage (Vmp)
- 33.8V
- Short Circuit Current (Isc)
- 13.42A
- Max Power Current (Imp)
- 12.43A
- Max Panels per String (600V)
- 14 panels
Based on NEC 600V residential limit. Actual string sizing should account for cold-temperature Voc rise. Consult your installer or use a string sizing tool for your specific location.
Mounting Requirements
- Dimensions
- 1722 x 1134 x 30 mm
- Weight
- 21 kg (46.3 lbs)
- Area per Panel
- 21.0 sq ft
- Weight per sq ft
- 2.2 lbs/sq ft
Recommended Inverter Types
- - Microinverters: Ideal for shaded roofs or complex layouts. Match to panels rated 420W+.
- - String Inverters: Cost-effective for unshaded arrays. Ensure MPPT range covers 33.8V.
- - Hybrid Inverters: Best if adding battery storage. Check DC input specs match panel Voc of 40.5V.
Frequently Asked Questions
How efficient is the REC TwinPeak 5 420W compared to other panels?
The TwinPeak 5 420W achieves 21.4% module efficiency, which is competitive for PERC residential panels. PERC panels typically range from 20.0% to 21.8%, and the TwinPeak 5 420W performs competitively within that range. Higher efficiency means more watts per square foot of roof space.
What is the warranty on the REC TwinPeak 5 420W?
REC provides a 20-year product warranty covering manufacturing defects and a 25-year performance warranty guaranteeing output levels. The performance warranty typically starts at 99% after year 1 and degrades by 0.4% per year, guaranteeing approximately 89.4% output at year 25. The product warranty is in line with industry standards.
How many REC TwinPeak 5 420W panels do I need for my home?
For a typical US home using 10,000 kWh per year, you need approximately 24 panels (10.1 kW system) assuming 4-5 peak sun hours per day. This varies significantly by location — homes in Arizona may need 21-23 panels while homes in the Pacific Northwest may need 26-28 panels. Your installer will calculate the exact number based on your utility bills, roof orientation, shading, and local solar resource.
What is the efficiency of the REC TwinPeak 5 420W?
The REC TwinPeak 5 420W achieves 21.4% module efficiency using PERC Mono cell technology. This is around the industry average for residential solar panels in 2026.
What warranty does the REC TwinPeak 5 420W include?
It comes with a 20-year product warranty and a 25-year performance warranty guaranteeing output at approximately 89.4% of rated power at the end of the warranty period.
How does the REC TwinPeak 5 420W perform in hot weather?
With a temperature coefficient of -0.32%/°C, the TwinPeak 5 420W experiences moderate power reduction in high temperatures. Every degree above 25°C reduces output by 0.32%.
What size system can I build with the REC TwinPeak 5 420W?
At 420W per panel, you would need approximately 20 panels for an 8 kW system or 24 panels for a 10 kW system. Each panel measures 1722 x 1134 mm (21.0 sq ft).
What inverter is best with the REC TwinPeak 5 420W?
The REC TwinPeak 5 420W works well with both string inverters and microinverters. For string inverters, choose one with a maximum input voltage above 40.5V and an MPPT voltage range that covers 33.8V. Microinverters rated for 420W+ panels are also an excellent choice, offering panel-level monitoring and shade tolerance. Popular options include Enphase IQ8 series microinverters and SolarEdge string inverters with power optimizers.
How long will the REC TwinPeak 5 420W last?
The REC TwinPeak 5 420W is built to last well beyond its 25-year performance warranty. With first-year degradation of 1% and annual degradation of 0.4% thereafter, the panel will still produce approximately 89.4% of its rated power after 25 years. Most modern solar panels continue generating useful power for 30-40 years, though output gradually decreases over time.
Is the REC TwinPeak 5 420W good for Arizona and other sunny states?
The REC TwinPeak 5 420W can work in hot states like Arizona, Nevada, and Texas, though its temperature coefficient of -0.32%/°C means it will lose some output on the hottest days. Consider panels with a lower (closer to 0) temperature coefficient if you live in an area with extreme heat. Higher sun exposure in these states means more total energy production throughout the year, often offsetting any heat-related losses.
Is the REC TwinPeak 5 420W worth the money?
The REC TwinPeak 5 420W delivers 21.4% efficiency, which is above the industry average of ~21%. Combined with a solid 20-year product warranty and 25-year performance guarantee, it offers strong value for homeowners seeking reliable solar generation.
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Last updated: February 2026