Table of Contents
- Introduction & Quick Guide
- 340W Solar Panel Fundamentals
- Top 340W Solar Panel Brands & Models (2025)
- Performance Analysis
- Applications & System Design
- Installation Considerations
- Cost Analysis & ROI
- Buying Guide & Selection Criteria
- Maintenance & Longevity
- Future Outlook & Alternatives
- Frequently Asked Questions
Introduction & Quick Guide
A 340 watt solar panel represents a mid-range power output option that has gained significant popularity in both residential and commercial solar installations. These panels offer an optimal balance between power generation, physical size, and cost-effectiveness, making them an attractive choice for property owners looking to maximize their solar investment.
What is a 340W Solar Panel and Why This Wattage Matters
A 340W solar panel is a photovoltaic module capable of producing 340 watts of electrical power under Standard Test Conditions (STC). This wattage places it in the medium-to-high efficiency category, typically featuring 60-72 solar cells arranged in a grid pattern. The 340W rating makes these panels particularly versatile for various applications, from residential rooftops to commercial installations.
The significance of the 340W rating lies in its sweet spot for efficiency and practicality. Unlike smaller panels that require more units to achieve desired power output, or larger panels that may be difficult to handle and install, 340W panels offer an optimal balance that appeals to both installers and system owners.
Quick Comparison: 340W vs 300W vs 400W Panels
| Panel Wattage | Typical Dimensions | Efficiency Range | Best Use Case | Price Range (2025) |
|---|---|---|---|---|
| 300W | 65″ x 39″ | 16-18% | Budget installations | $150-$200 |
| 340W | 67″ x 40″ | 18-21% | Balanced performance | $170-$250 |
| 400W | 79″ x 39″ | 20-22% | Space-constrained roofs | $220-$300 |
Who Should Consider 340W Panels
Residential Applications:
- Homeowners with medium to large roof spaces
- Properties seeking balanced cost-per-watt ratios
- Installations where panel quantity flexibility is desired
Commercial Applications:
- Small to medium commercial buildings
- Warehouses and industrial facilities
- Agricultural operations and farm buildings
340W Solar Panel Fundamentals
Technical Specifications Explained
Understanding the key electrical characteristics of 340W solar panels is crucial for proper system design and performance expectations:
Open Circuit Voltage (Voc): Typically ranges from 40-46V for 340W panels. This represents the maximum voltage the panel produces when not connected to a load.
Short Circuit Current (Isc): Usually between 9-11 amps, representing the maximum current the panel can produce under ideal conditions.
Maximum Power Point Voltage (Vmp): Generally 32-38V, this is the operating voltage at which the panel produces its rated 340W output.
Maximum Power Point Current (Imp): Typically 9-10.5 amps, representing the current at maximum power output.
Efficiency Ratings and What They Mean
Most quality 340W solar panels achieve efficiency ratings between 18-22%. This means they convert 18-22% of available sunlight into usable electricity. Higher efficiency panels offer several advantages:
- Space optimization: More power from smaller roof areas
- Reduced installation costs: Fewer panels needed for target power output
- Better performance in partial shading: Advanced cell designs minimize power loss
Cell Types: Monocrystalline vs Polycrystalline in 340W Panels
Monocrystalline 340W Panels:
- Higher efficiency (20-24%)
- Better performance in low-light conditions
- Sleeker appearance with uniform black color
- Higher price point but better long-term value
Polycrystalline 340W Panels:
- Moderate efficiency (15-20%)
- Lower manufacturing costs
- Blue-tinted appearance
- Note: Polycrystalline panels are largely discontinued in new production as of 2023
Physical Dimensions and Weight Considerations
Standard 340W solar panels typically measure:
- Length: 67-79 inches (1700-2000mm)
- Width: 39-41 inches (1000-1050mm)
- Thickness: 1.2-1.6 inches (30-40mm)
- Weight: 40-50 pounds (18-23kg)
These dimensions make 340W panels manageable for installation while maximizing power density per square foot of roof space.
Top 340W Solar Panel Brands & Models (2025)
Tier 1 Manufacturers
Note: LG discontinued solar panel manufacturing in June 2022, making their NeON 2 340W panels no longer available for new installations.
Panasonic HIT Series:
- Efficiency: Up to 21.2%
- Temperature coefficient: -0.26%/°C
- 25-year product warranty
- Excellent low-light performance
REC Alpha Series:
- Efficiency: 19.9-21.7%
- Half-cut cell technology
- 20-year product warranty
- Excellent shade tolerance
Value Brands
Canadian Solar HiKu Series:
- Efficiency: 18.5-19.5%
- Competitive pricing
- 12-year product warranty
- Strong global presence
Trina Solar Vertex Series:
- Efficiency: 19-20%
- Multi-busbar technology
- 12-year product warranty
- Good performance-to-price ratio
Q CELLS Q.PEAK DUO Series:
- Efficiency: 18.8-19.5%
- Anti-reflective coating
- 12-year product warranty
- German engineering quality
Detailed Comparison Table
| Brand/Model | Efficiency | Voc (V) | Isc (A) | Warranty | Price Range |
|---|---|---|---|---|---|
| Panasonic HIT-340 | 21.2% | 69.7 | 6.14 | 25 years | $280-$320 |
| REC Alpha 340 | 19.9% | 41.1 | 10.53 | 20 years | $220-$260 |
| Canadian Solar CS6K-340 | 18.5% | 46.0 | 9.34 | 12 years | $170-$220 |
| Trina Solar TSM-340 | 19.0% | 40.4 | 10.75 | 12 years | $170-$210 |
Discontinued Models to Avoid
LG NeON 2 Series: While these were excellent panels, LG discontinued solar manufacturing in June 2022. Avoid purchasing remaining inventory due to potential warranty and service issues.
340W Solar Panel Performance Analysis
Real-World Power Output vs STC Ratings
Standard Test Conditions (STC) represent ideal laboratory conditions that rarely occur in real-world installations. Understanding actual performance expectations is crucial:
STC Conditions:
- 1,000 watts per square meter irradiance
- 25°C (77°F) cell temperature
- Air mass 1.5 spectrum
Real-World Performance Factors:
- Temperature effects: Most 340W panels lose 0.35-0.45% efficiency per degree Celsius above 25°C
- Irradiance variations: Actual sunlight intensity varies throughout the day and seasons
- Soiling and dust: Can reduce output by 2-5% annually without cleaning
- System losses: Inverter efficiency, wiring losses, and shading typically reduce system output by 10-20%
Temperature Coefficient Impact on Performance
Temperature coefficient is a critical specification often overlooked by buyers. For 340W panels:
Premium panels: -0.25% to -0.30%/°C (Panasonic)
Standard panels: -0.35% to -0.40%/°C (Most tier-1 manufacturers)
Budget panels: -0.40% to -0.50%/°C (Some value brands)
In hot climates, a panel with a better temperature coefficient can produce significantly more energy over its lifetime.
Shading Tolerance and Bypass Diode Configuration
Modern 340W panels incorporate bypass diodes to minimize power loss from partial shading:
- Standard configuration: 3 bypass diodes protecting 20-cell sections
- Half-cut cell designs: 6 bypass diodes protecting 10-cell sections
- Optimizer-ready panels: Compatible with power optimizers for maximum shade tolerance
Seasonal Performance Variations
340W panel output varies significantly by season and location:
Summer Performance:
- Higher irradiance levels
- Reduced efficiency due to heat
- Longer daylight hours
Winter Performance:
- Lower irradiance levels
- Improved efficiency in cold temperatures
- Shorter daylight hours
- Potential snow coverage issues
Applications & System Design
Residential Rooftop Installations
340W panels are ideal for residential solar panel installations due to their balanced size and power output:
Typical Residential System Sizes:
- Small system (3-5 kW): 9-15 panels
- Medium system (6-8 kW): 18-24 panels
- Large system (10-12 kW): 30-35 panels
Roof Requirements:
- Minimum 200 square feet of unshaded roof space
- South, southeast, or southwest orientation preferred
- Roof pitch between 15-40 degrees optimal
- Structural capacity to support 2.5-3 lbs per square foot
Commercial Applications
340W panels work well for small to medium commercial installations:
- Retail buildings: 20-100 kW systems
- Warehouses: 100-500 kW systems
- Office buildings: 50-200 kW systems
- Agricultural facilities: Variable sizing based on needs
Off-Grid Systems
340W panels are excellent for off-grid applications:
RV and Marine:
- 1-4 panels typical for RV installations
- Flexible mounting options available
- 12V and 24V system compatibility
Cabin and Remote Properties:
- 4-12 panels for basic electrical needs
- Battery storage integration required
- Generator backup recommended
System Sizing: How Many 340W Panels Do You Need?
Use this formula to estimate panel quantity:
Panels Needed = (Annual kWh Usage ÷ Local Solar Hours ÷ 365 days) ÷ 0.34 kW
Example Calculations:
- 10,000 kWh annual usage, 5 sun hours daily: (10,000 ÷ 5 ÷ 365) ÷ 0.34 = 16 panels
- 15,000 kWh annual usage, 4 sun hours daily: (15,000 ÷ 4 ÷ 365) ÷ 0.34 = 28 panels
Installation Considerations
Roof Space Requirements and Layout Optimization
Proper planning ensures maximum energy production from your 340W panel system:
Space Planning:
- Allow 3-4 inches between panels for airflow
- Maintain 3-foot setbacks from roof edges (code requirement)
- Consider access pathways for maintenance
- Account for roof penetrations and obstacles
Orientation and Tilt Optimization:
- Ideal orientation: True south (180° azimuth)
- Acceptable range: Southeast to southwest (135-225° azimuth)
- Optimal tilt: Equal to latitude ± 15°
- Minimum tilt: 5° for self-cleaning
Mounting Systems and Hardware Compatibility
340W panels are compatible with most standard mounting systems:
Roof-Mounted Systems:
- Rail systems: Most common, uses aluminum rails
- Railless systems: Direct panel-to-roof attachment
- Ballasted systems: For flat roofs, no penetrations
Ground-Mounted Systems:
- Fixed-tilt systems: Cost-effective, seasonal adjustment possible
- Tracking systems: Single or dual-axis for maximum production
- Pole-mounted systems: For smaller arrays or specific applications
Electrical Considerations
Inverter Matching:
- String inverters: 8-12 panels per string typical
- Power optimizers: One per panel for maximum flexibility
- Microinverters: One per panel, highest system reliability
String Sizing Calculations:
- Maximum string voltage must not exceed inverter limit
- Minimum string voltage must meet inverter start-up requirements
- Consider temperature effects on voltage
Code Compliance and Permitting Requirements
2025 code requirements for 340W panel installations:
- NEC 2023 compliance: Latest electrical code requirements
- Rapid shutdown: Required for rooftop installations
- Arc fault protection: AFCI devices required
- Ground fault protection: GFCI protection required
- Structural analysis: May be required for large systems
Cost Analysis & ROI
Current Pricing Trends (2025)
340W solar panel prices have stabilized in 2025 after significant volatility in previous years:
Price per Watt Analysis:
- Premium brands: $0.80-$1.00 per watt
- Tier-1 brands: $0.50-$0.80 per watt
- Value brands: $0.30-$0.65 per watt
Complete Panel Pricing:
- Budget 340W panels: $170-$220
- Mid-range 340W panels: $200-$270
- Premium 340W panels: $270-$340
Total System Costs Including Installation
Complete system costs vary significantly by location and complexity:
Residential System Costs (per watt installed):
- Equipment: $0.50-$0.80 per watt
- Installation labor: $0.40-$0.70 per watt
- Permitting and inspection: $0.10-$0.20 per watt
- Sales and marketing: $0.30-$0.50 per watt
- Total system cost: $2.50-$3.50 per watt
Example 6.8 kW System (20 x 340W panels):
- Equipment cost: $4,000-$6,000
- Installation cost: $3,000-$5,000
- Other costs: $3,000-$4,000
- Total project cost: $17,000-$24,000
Payback Period Calculations
Solar payback periods depend on local electricity rates and incentives:
Factors Affecting Payback:
- Local electricity rates ($/kWh)
- Solar resource availability (sun hours)
- Federal and state incentives
- Net metering policies
- System performance and degradation
Typical Payback Periods by Region:
- Southwest US: 6-9 years
- California: 7-10 years
- Northeast: 8-12 years
- Southeast: 9-13 years
- Midwest: 10-15 years
Financing Options and Incentives
Federal Tax Credit (2025):
- Currently 30% federal investment tax credit, but facing potential elimination
- Congressional proposals may end the credit by December 2025
- Available for residential and commercial installations while in effect
For homeowners looking to make solar more affordable, exploring various solar panel financing options can help you find the payment plan that best fits your budget and maximizes your long-term savings.
Financing Options:
- Cash purchase: Best ROI, immediate tax benefits
- Solar loans: 2.99-7.99% APR typical
- Solar leases: $0 down, monthly payments
- Power purchase agreements (PPAs): Pay per kWh produced
Buying Guide & Selection Criteria
Key Factors to Evaluate When Choosing 340W Panels
Performance Criteria:
- Efficiency rating: Higher efficiency means more power from limited space
- Temperature coefficient: Critical for hot climate performance
- Low-light performance: Important for cloudy regions
- Degradation rate: Annual power loss over time
Quality Indicators:
- Tier-1 manufacturer status: Bloomberg New Energy Finance ranking
- Certifications: IEC 61215, IEC 61730, UL 1703
- Manufacturing location: Quality control and shipping considerations
- Financial stability: Company’s ability to honor warranties
Warranty Comparison
Product Warranty (Manufacturing Defects):
- Premium brands: 20-40 years (Panasonic)
- Tier-1 brands: 12-20 years (REC, Q CELLS)
- Value brands: 10-12 years (Most Chinese manufacturers)
Performance Warranty (Power Output):
- Linear warranties: Gradual degradation allowance (0.5-0.8% annually)
- Tiered warranties: Step-down at specific intervals
- Typical coverage: 80-90% of original power at 25 years
Where to Buy: Authorized Dealers vs Online Retailers
Authorized Dealers:
- Pros: Full warranty support, professional installation, local service
- Cons: Higher prices, limited selection
- Best for: Complete system installations
Online Retailers:
- Pros: Lower prices, wide selection, detailed specifications
- Cons: Limited warranty support, shipping costs, self-installation required
- Best for: DIY installations, system expansions
Wholesale/Direct:
- Pros: Lowest prices, bulk purchasing options
- Cons: Minimum order quantities, limited support
- Best for: Large installations, professional installers
Red Flags to Avoid When Purchasing
Warning Signs:
- Prices significantly below market rates
- Unknown or unverifiable manufacturer
- Missing or questionable certifications
- Unrealistic performance claims
- No local warranty support
- Pressure sales tactics
- Upfront payment requirements
Due Diligence Checklist:
- Verify manufacturer’s Tier-1 status
- Check Bloomberg New Energy Finance rankings
- Review warranty terms and conditions
- Confirm local dealer/service network
- Research installer credentials and reviews
- Obtain multiple quotes for comparison
Maintenance & Longevity
Expected Lifespan and Degradation Rates
Quality 340W solar panels are designed for 25-30 year operational life:
Degradation Patterns:
- Initial degradation: 1-3% in first year (light-induced degradation)
- Annual degradation: 0.5-0.8% per year thereafter
- End-of-warranty output: 80-90% of original power at 25 years
- Actual lifespan: Many panels continue producing 70%+ power at 30+ years
Factors Affecting Longevity:
- Climate conditions (heat, humidity, UV exposure)
- Installation quality and mounting system
- Panel quality and manufacturing standards
- Maintenance frequency and quality
Maintenance Requirements and Best Practices
Routine Maintenance Tasks:
- Visual inspection: Quarterly check for damage or debris
- Performance monitoring: Monthly production review
- Cleaning: As needed based on soiling conditions
- Vegetation management: Trim trees/bushes causing shading
To maintain optimal performance and extend the lifespan of your 340W panels, consider investing in professional solar panel cleaning services that use specialized equipment and techniques to safely remove dirt, debris, and other contaminants.
Professional Maintenance:
- Annual inspection: Electrical connections and mounting hardware
- Inverter maintenance: Filter cleaning, firmware updates
- Performance analysis: Identify underperforming panels
- Safety checks: Grounding, arc fault protection
Performance Monitoring and Troubleshooting
Monitoring Systems:
- Basic monitoring: Production meters, mobile apps
- Advanced monitoring: Panel-level optimization and monitoring
- Professional monitoring: Remote diagnostics and alerts
Common Issues and Solutions:
- Reduced output: Check for shading, soiling, or equipment failure
- Hot spots: May indicate cell damage or poor connections
- Ground faults: Require immediate professional attention
- Arc faults: Potential fire hazard, needs expert diagnosis
Performance Benchmarks:
- Compare actual vs. expected production monthly
- Monitor individual panel performance if equipped
- Track efficiency degradation over time
- Document maintenance activities and results
Future Outlook & Alternatives
Technology Trends Affecting 340W Panel Relevance
The solar industry continues evolving rapidly, affecting the 340W segment:
Emerging Technologies:
- Perovskite tandem cells: Potential for 30%+ efficiency by 2030
- Heterojunction technology: Combining advantages of different cell types
- Bifacial panels: Generating power from both sides
- Flexible panels: New installation possibilities
Manufacturing Trends:
- Larger wafer sizes (210mm becoming standard)
- Half-cut and third-cut cell technologies
- Multi-busbar designs for better current collection
- Automated manufacturing reducing costs
When to Consider Higher Wattage Alternatives
Choose 400W+ Panels When:
- Limited roof space requires maximum power density
- Reducing installation labor costs is priority
- Structural limitations restrict panel quantity
- Future expansion may be difficult
Stick with 340W Panels When:
- Adequate roof space is available
- Budget constraints are primary concern
- Flexibility in system sizing is desired
- Proven track record is important
Emerging Technologies
Bifacial 340W Panels:
- Generate 5-20% additional power from rear side
- Best suited for ground-mount installations
- Require appropriate mounting and ground surfaces
- Premium pricing but improving economics
Half-Cut Cell Technology:
- Reduced resistive losses improve efficiency
- Better performance in partial shading
- Lower hot-spot temperatures
- Becoming standard in premium panels
Smart Panel Integration:
- Built-in optimization and monitoring
- Improved safety features
- Enhanced system flexibility
- Higher initial cost but reduced complexity
Frequently Asked Questions
What is a 340 watt solar panel?
A 340 watt solar panel is a photovoltaic module that produces 340 watts of electrical power under Standard Test Conditions (1000 W/m² irradiance, 25°C cell temperature). These panels typically feature 60-72 solar cells and measure approximately 67″ x 40″ x 1.5″.
How much power does a 340W solar panel produce daily?
Daily power production depends on location and weather conditions. In areas with 5 peak sun hours, a 340W panel produces approximately 1.7 kWh per day (340W × 5 hours). Annual production typically ranges from 400-650 kWh depending on geographic location.
Are 340 watt solar panels good for residential use?
Yes, 340W panels are excellent for residential applications. They offer a good balance of power output, physical size, and cost-effectiveness. A typical home solar system uses 15-25 panels of this size, producing 5-8.5 kW of total capacity.
Why choose 340W over 300W or 400W panels?
340W panels offer the sweet spot between cost and performance. Compared to 300W panels, they provide more power per panel, reducing installation costs. Compared to 400W panels, they’re more affordable and easier to handle during installation while still providing substantial power output.
How many 340W solar panels do I need for my home?
The number depends on your electricity usage and local solar conditions. Divide your annual kWh usage by your local solar production factor. For example, a home using 12,000 kWh annually in an area with good solar resources might need 18-22 panels (6.1-7.5 kW system).
What’s the lifespan of a 340W solar panel?
Quality 340W solar panels last 25-30+ years. Most manufacturers warranty 80-90% power output at 25 years. Panels typically continue producing electricity beyond their warranty period, often at 70%+ of original capacity after 30 years.
How much do 340W solar panels cost?
In 2025, 340W solar panels cost $170-$340 each, depending on brand and quality. Premium brands cost $270-$340, while value brands range from $170-$220. Complete installed systems cost $2.50-$3.50 per watt.
Can I install 340W solar panels myself?
While technically possible, DIY installation is not recommended for most homeowners. Solar installations require electrical expertise, permit knowledge, and safety equipment. Professional installation ensures code compliance, optimal performance, and warranty coverage.
Do 340W panels work in cloudy weather?
Yes, 340W solar panels produce electricity in cloudy conditions, though at reduced output. They typically generate 10-25% of rated power on overcast days. Modern panels are designed to capture diffused sunlight effectively.
What maintenance do 340W solar panels require?
340W solar panels require minimal maintenance: periodic visual inspections, occasional cleaning if soiling is significant, and annual professional checkups. Most panels are self-cleaning in areas with regular rainfall. Monitor performance regularly to identify any issues early.