Mission Solar MSE PERC 66 SQ9S 420W
The Mission Solar MSE PERC 66 SQ9S extends the SQ9S platform to 132 half-cut PERC cells, delivering 420W in a US-made module ideal for higher-wattage residential and small-commercial arrays.
⚠️ Specs Pending Verification
Last review attempt: 2026-05-27 · See our methodology
At a glance
Value comparison (same class)
How the Mission Solar MSE PERC 66 SQ9S 420W stacks up against other panels in the 420W±100W range.
| Model | Score | Efficiency | $/W | Warranty | Value |
|---|---|---|---|---|---|
| ★ THIS — Mission Solar MSE PERC 66 SQ9S 420W | 67 | 20.6% | — | 12 yr | Budget |
| REC TwinPeak 5 420W | 82 | 21.4% | — | 20 yr | Good |
| Trina Solar Vertex S 420W | 80 | 21.3% | — | 15 yr | Solid |
| Canadian Solar CS6R 420W | 76 | 21% | — | 12 yr | Solid |
Where this panel works best
High snow load rating (5400 Pa) makes this panel well-suited for northern states with heavy winter accumulation.
Click a state for the full local solar buying guide (incentives, payback, top installers).
Pricing
Public pricing data is limited for the Mission Solar MSE PERC 66 SQ9S 420W. Request multiple installer quotes to benchmark per-watt cost in your area.
Live historical pricing trends coming in v0.3 (integrating manufacturer MSRP + reseller data).
Recent news about Mission Solar
Latest manufacturer announcements, shipment updates, and product roadmap from public sources:
Best for these scenarios
- ✓ Roof area: 256 – 619 ft² (12–29 panels for a 5–12 kW system)
- ✓ Monthly usage: 680 – 1,644 kWh/month (assuming 4.5 peak-sun hrs/day average US)
- ✓ Best for: Residential and small-commercial roofs that want fewer, larger US-made panels and prioritize domestic content over peak efficiency.
- ✗ NOT ideal for: consistently extreme heat (>105°F summers) — high temp coefficient reduces output
Full Datasheet — every parameter ▾
Key Specifications
| Brand | Mission Solar |
| Model | Mission Solar MSE PERC 66 SQ9S 420W |
| Power Output | 420W |
| Efficiency | 20.6% |
| Power Density | 19.7 W/sq ft |
| Cell Type | PERC Mono |
| Cell Count | 132 cells |
| Dimensions | 1909 x 1038 x 35 mm |
| Weight | 22 kg |
| Open Circuit Voltage (Voc) | 45.9V |
| Max Power Voltage (Vmp) | 38.4V |
| Short Circuit Current (Isc) | 11.62A |
| Max Power Current (Imp) | 10.95A |
| Temp Coefficient (Pmax) | -0.36%/°C |
| Product Warranty | 12 years |
| Performance Warranty | 25 years |
| First Year Degradation | 2% |
| Annual Degradation | 0.55% |
| Country of Manufacture | United States |
| Certifications | IEC 61215, IEC 61730, UL 1703 |
| Snow Load | 5400 Pa (112.8 psf) — Heavy Snow Rated |
| Wind Load | 2400 Pa (50.1 psf) |
Pros & Cons
Pros
- ✓ Made in USA (San Antonio, TX)
- ✓ 420W output reduces panel count per system
- ✓ 132 half-cut PERC cells for better shading tolerance
- ✓ Heavy-duty snow (5400 Pa) and wind (2400 Pa) loads
Cons
- ✗ Larger 1909mm × 1038mm form factor needs more roof space per panel
- ✗ 12-year product warranty lags REC Alpha (25-yr) and Q CELLS Q.TRON (25-yr)
- ✗ PERC technology slowly being replaced by TOPCon in 2025-2026
Installation & Compatibility
System Voltage & String Sizing
- Open Circuit Voltage (Voc)
- 45.9V
- Max Power Voltage (Vmp)
- 38.4V
- Short Circuit Current (Isc)
- 11.62A
- Max Power Current (Imp)
- 10.95A
- Max Panels per String (600V)
- 13 panels
Based on NEC 600V residential limit. Actual string sizing should account for cold-temperature Voc rise.
Mounting Requirements
- Dimensions
- 1909 x 1038 x 35 mm
- Weight
- 22 kg (48.5 lbs)
- Area per Panel
- 21.3 sq ft
- Weight per sq ft
- 2.3 lbs/sq ft
Recommended Inverter Types
- - Microinverters: Ideal for shaded roofs. Match to panels rated 420W+.
- - String Inverters: Cost-effective for unshaded arrays. MPPT must cover 38.4V.
- - Hybrid Inverters: Best if adding battery storage. Check Voc of 45.9V.
Is the Mission Solar MSE PERC 66 SQ9S 420W Worth It?
The Mission Solar MSE PERC 66 SQ9S 420W delivers 420W of power at 20.6% module efficiency, which is near the current industry average of approximately 21%. While not the highest-efficiency option on the market, it may offer compelling value depending on price and your available roof space.
From a warranty perspective, the MSE PERC 66 SQ9S 420W comes with a standard 12-year product warranty and a 25-year performance guarantee. The industry standard for product warranties ranges from 12 to 25 years, so you may want to weigh this shorter warranty against the overall system cost. At the end of 25 years, the panel is guaranteed to still produce approximately 84.8% of its rated output, with first-year degradation of 2% and just 0.55% per year after that.
Pricing varies by region and installer, but the MSE PERC 66 SQ9S 420W's combination of 20.6% efficiency and 12-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 -0.36%/°C is average. This is on the higher end, meaning noticeable power reduction when temperatures climb well above 25°C (77°F). If you live in a consistently hot climate, consider a panel with a lower temperature coefficient. Overall, the Mission Solar MSE PERC 66 SQ9S 420W can be a reasonable choice depending on your budget and performance requirements.
Frequently Asked Questions
What is the efficiency of the Mission Solar MSE PERC 66 SQ9S 420W?
The Mission Solar MSE PERC 66 SQ9S 420W achieves 20.6% module efficiency using PERC Mono cell technology. This is around the industry average for residential solar panels in 2026.
What warranty does the Mission Solar MSE PERC 66 SQ9S 420W include?
It comes with a 12-year product warranty and a 25-year performance warranty guaranteeing output at approximately 84.8% of rated power at the end of the warranty period.
How does the Mission Solar MSE PERC 66 SQ9S 420W perform in hot weather?
With a temperature coefficient of -0.36%/°C, the MSE PERC 66 SQ9S 420W experiences moderate power reduction in high temperatures. Every degree above 25°C reduces output by 0.36%.
What size system can I build with the Mission Solar MSE PERC 66 SQ9S 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 1909 x 1038 mm (21.3 sq ft).
What inverter is best with the Mission Solar MSE PERC 66 SQ9S 420W?
The Mission Solar MSE PERC 66 SQ9S 420W works well with both string inverters and microinverters. For string inverters, choose one with a maximum input voltage above 45.9V and an MPPT voltage range that covers 38.4V. 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 Mission Solar MSE PERC 66 SQ9S 420W last?
The Mission Solar MSE PERC 66 SQ9S 420W is built to last well beyond its 25-year performance warranty. With first-year degradation of 2% and annual degradation of 0.55% thereafter, the panel will still produce approximately 84.8% 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 Mission Solar MSE PERC 66 SQ9S 420W good for Arizona and other sunny states?
The Mission Solar MSE PERC 66 SQ9S 420W can work in hot states like Arizona, Nevada, and Texas, though its temperature coefficient of -0.36%/°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 Mission Solar MSE PERC 66 SQ9S 420W worth the money?
The Mission Solar MSE PERC 66 SQ9S 420W delivers 20.6% efficiency, which is near the industry average of ~21%. Combined with a standard 12-year product warranty and 25-year performance guarantee, it offers reasonable value for homeowners seeking reliable solar generation.
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Last updated: May 2026