Choosing the right solar panels can determine your investment efficiency for the next 25 years. Many households and businesses have spent hundreds of millions of dong but failed to achieve expected performance due to choosing the wrong panel type or not understanding the technology.
This article will guide you through 3 important steps: understanding current panel technology, evaluating factors affecting performance, and making smart selection decisions based on actual needs and budget.
Solar Panel Technology: What’s the Optimal Choice for You?
4 Main Technologies – Real Comparison
The current solar panel market is dominated by 4 main technologies, each with distinct advantages and disadvantages suitable for different conditions:
Mono PERC (Monocrystalline PERC)
- Efficiency: 20-22% (actual commercial conditions)
- Advantages: Stable efficiency, good performance in low-light conditions
- Disadvantages: Higher cost than Poly
- Suitable for: Limited roof area, want to maximize production
Polycrystalline (Multi-crystalline)
- Efficiency: 17-19% (declining market share)
- Advantages: Reasonable cost, high durability
- Disadvantages: Lower efficiency, larger size
- Suitable for: Limited budget, wide roof area
HJT (Heterojunction)
- Efficiency: 22-24% (high-end technology)
- Advantages: High efficiency, less affected by temperature
- Disadvantages: Highest cost, not yet popular in Vietnam
- Suitable for: Large-scale projects, maximum efficiency requirements
Bifacial (Dual-sided)
- Efficiency: Collects light from both sides (5-20% increase over single-sided panels)
- Advantages: Collects reflected light, can increase production
- Disadvantages: Requires special installation design
- Suitable for: Light-colored roofs, areas with much reflected light
Solar Panel Structure – Decoding Operating Principles
Solar panels are constructed from 6 main material layers, each playing an important role in the light-to-electricity conversion process:
- Tempered glass: Protects inner layers from environmental impact
- EVA encapsulation layer: Bonds and protects photovoltaic cells
- Photovoltaic cells: Where light-to-electricity conversion occurs
- Second EVA layer: Enhances durability and insulation
- Backsheet: Protective base layer, usually waterproof polymer
- Aluminum frame: Increases rigidity and easy installation
The photovoltaic principle works when photons (light particles) collide with silicon cells, creating the photovoltaic effect and generating direct current. Conversion efficiency depends on silicon quality and manufacturing technology.
2025 Trend: TOPCon Rising
TOPCon Technology (Tunnel Oxide Passivated Contact)
TOPCon is becoming the dominant technology in the solar panel industry. Leading manufacturers like Longi, Trina Solar, JinkoSolar are investing heavily in this technology:
- Efficiency: 24-26% (2-4% higher than PERC)
- Advantages: Can be produced on existing PERC production lines with low upgrade costs
- Expected market share: From 10% in 2022 to 60% by 2033
- In Vietnam: Already available from major brands
Perovskite Technology – Future Potential
Important note: Although research shows Perovskite panels have potential for high efficiency (over 30% in laboratories), commercialization still faces many challenges:
- Durability issues: Haven’t passed long-term stability tests
- Production costs: Still in research phase
- Commercialization timeline: Expected after 2030
- Recommendation: Don’t wait for this technology for current investment decisions
Solar Panel Performance: Factors Determining Output
How to Evaluate Real Performance
Solar panel performance depends not only on technical specifications but is also affected by real conditions. Evaluation should consider:
Influencing factors:
- Ambient temperature conditions (35-45°C in Vietnam)
- Solar radiation levels (4.0-5.5 kWh/m²/day)
- Cleaning and maintenance status
- Installation angle and panel direction (optimal: South-facing, 15-20° angle)
- Equipment age
Important note: In tropical climate conditions like Vietnam, actual performance is typically 15-20% lower than laboratory conditions due to high temperature and humidity effects.
“Enemies” of Panel Performance
- High temperature: Each degree C increase reduces 0.3-0.5% efficiency
- Partial shading: Can reduce 50-80% output of entire panel
- Dust accumulation: Reduces 5-15% efficiency without regular cleaning
- Non-optimal installation angle: Can reduce 10-30% production
- Natural aging: Good quality panels degrade 0.5-0.7%/year
Solar Panel Selection: Decision Matrix for Customer Groups
Households: Cost Optimization
Priority criteria:
- Reasonable investment cost (15-25 million VND/kWp installed)
- Long-term warranty (25-year performance, 10-12 year product)
- Reputable brand with good after-sales service
Specific recommendations: Mono PERC or TOPCon panels from brands:
- Tier 1: Longi Solar, JinkoSolar, Trina Solar, Canadian Solar
- With Vietnam offices: JA Solar, Risen Energy
Expected payback time: 7-10 years (depending on consumption level and electricity policy)
Businesses: Focus on Efficiency
Priority criteria:
- High efficiency to maximize usable area
- Long-term operational reliability (uptime >98%)
- Future expansion capability
Specific recommendations: TOPCon or HJT panels from Longi Solar, Trina Solar, JinkoSolar for high-efficiency projects.
Economic benefits: Save 20-40% on electricity bills for manufacturing businesses, especially effective for industries with high daytime electricity consumption.
Checklist: 10 Questions Before Buying
☐ Does the panel have 25-year performance warranty?
☐ Does it have IEC 61215 and IEC 61730 certifications?
☐ What is the annual performance degradation rate?
☐ Does the supplier have a representative office in Vietnam?
☐ Is there maintenance and spare parts replacement service?
☐ Do panel specifications match the inverter?
☐ Is the price competitive compared to market?
☐ What are delivery and installation timeframes?
☐ Is there financial support policy?
☐ What are previous customer reviews?
Practical Applications & Development Trends
Developing Application Fields
Smart Agriculture (Agri-PV)
Floating solar panels applied in aquaculture, producing electricity while reducing water evaporation.
Green Transportation
Electric vehicle charging stations using solar energy are being deployed in major cities.
Green Construction (BIPV)
Building-integrated photovoltaics are becoming a trend in modern projects.
Current Support Policies (Updated 2025)
Decree 135/2024/ND-CP on rooftop solar self-production, self-consumption:
- Application scope: Households, businesses, industrial zones
- Excess electricity: Can sell maximum 20% of installed capacity
- Excess purchase price: According to previous year’s average market electricity price
- Procedures: Simplified for systems under 100kW
Other incentives:
- Import tax exemption on renewable energy equipment
- Preferential loan support from banks
- Simplified registration procedures for small projects
15 Frequently Asked Questions
Performance & Operation
Q1: Do solar panels work on rainy days?
A1: Yes, at 10-25% capacity compared to sunny days. Panels still collect diffused light through clouds.
Q2: Why does efficiency decrease in summer?
A2: High temperatures (above 35°C) reduce efficiency by 15-20%. This is a natural characteristic of silicon panel technology.
Q3: How often should panels be cleaned?
A3: Every 3-6 months depending on environment. Industrial areas should clean more frequently.
Selection & Investment
Q4: Should I choose Mono PERC or TOPCon panels?
A4: TOPCon if budget allows (2-4% higher efficiency). Mono PERC is still good for limited budgets.
Q5: Cost of installing 5kWp system for households?
A5: About 90-150 million VND (including panels, inverter, installation).
Q6: Actual payback time?
A6: 7-10 years for households, 5-7 years for businesses (depending on electricity consumption).
Installation & Maintenance
Q7: Can solar panels be installed on metal roofs?
A7: Yes, but need to check load capacity (15-20kg/m²) and reinforce if needed.
Q8: Do panels affect Wi-Fi signals?
A8: No. Solar panels operate on completely different frequency bands.
Q9: Annual maintenance costs?
A9: About 0.5-1% of total investment cost (mainly cleaning and inspection).
Q10: Can panels withstand strong storms?
A10: Good quality panels can withstand Category 12 winds if properly installed.
Q11: Is insurance needed for the system?
A11: Should buy fire and natural disaster insurance to protect investment.
Q12: When should panels be replaced?
A12: When efficiency drops below 80% (usually after 25-30 years of use).
Q13: Are panels recyclable?
A13: 95% of materials can be recycled (silicon, aluminum, glass, precious metals).
Q14: Does the system work during grid outages?
A14: No, unless there’s battery storage or hybrid inverter.
Q15: Should I invest in battery storage?
A15: Currently not necessary in Vietnam due to favorable net-metering policy.
Support Tools & Reference Resources
Factors to Consider in Evaluation
Actual electricity needs
- Analyze last 12 months’ electricity bills
- Calculate average consumption: kWh/month
- Identify seasonal variations
Installation conditions
- Available roof area (minimum 30m² for 5kWp)
- Direction and tilt angle (optimal: South-facing, 15-20°)
- Shading from surrounding structures
- Roof structural load capacity
Financial capability
- Initial investment capital: 15-25 million/kWp
- Access to bank loans (6-9% annual interest)
- Expected electricity savings: 1.2-1.8 million/kWp/year
Supplier Evaluation Criteria
Product:
- International certifications (IEC, TUV, CE)
- Clear and reputable warranty
- Spare parts availability
Service:
- Over 3 years practical experience
- Certified technical team
- 24/7 after-sales service
Financial:
- Detailed, transparent quotations
- Flexible payment policies
- Bank loan procedure support
Conclusion
Choosing suitable solar panels is an important decision affecting investment efficiency for many years. With rapid development of TOPCon technology and support policies from Decree 135/2024, this is a favorable time to invest in solar energy.
Recommendations:
- Households: Choose Mono PERC or TOPCon panels from reputable brands
- Businesses: Prioritize TOPCon technology for high efficiency
- All: Focus on supplier quality rather than just price comparison
Vietnam’s renewable energy market is developing strongly. To maximize this opportunity, consult experts and choose solutions suitable for your specific conditions.
Information in this article is updated as of June 2025. Due to the rapidly changing nature of the solar energy industry, some information may need updates over time. For latest information, please consult specialized sources or contact advisory experts.
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