As electricity prices continue to fluctuate and the demand for clean energy grows, rooftop solar has become one of the leading solutions for households and businesses. However, before making an investment, many customers still have concerns about safety, performance, and cost.
Below are the 10 most frequently asked questions, answered by Thinh Phong, a company specializing in renewable energy solutions.
1. Is a permit required to install rooftop solar?
According to Decree 58/2025/NĐ-CP, rooftop solar systems under 100 kW that are self-produced, self-consumed, and not selling excess electricity to the grid do not require construction permits or electricity operation licenses.
However, owners must complete the mandatory notification procedure before putting the system into operation.
The notification process includes two steps:
• Step 1: Notify the Department of Industry and Trade (DOIT)
Users access the National Public Service Portal, search for the procedure “Notification of the development of self-produced, self-consumed rooftop solar systems connected to the national power grid”, download Form MU01.docx, fill in the information, and submit it online to the local DOIT.
Processing time is fast, and the required documents are simple.
• Step 2: Notify EVN (Electricity of Vietnam)
Customers may notify via the EVN CSKH app, hotline, official fanpage, or directly at the local power utility office.
Provide the customer code and contact information. EVN will call back to confirm and finalize the process.
Thus, rooftop solar systems under 100 kW do not need a permit, but they must be reported in accordance with regulations to ensure safe grid connection and proper management.
2. Does the system generate electricity during cloudy or rainy weather?
Yes. The system continues to operate even in poor weather conditions, although output may decrease.
Solar panels rely on light, so they still produce around 10–50% of their capacity depending on cloud cover and rainfall intensity.
3. Is rooftop solar safe? Is there a risk of fire?
Thinh Phong representative confirms that the risk of fire is almost zero when installed properly.
All projects implemented by the company use DC circuit breakers, TUV/UL-certified cables, and full grounding according to IEC standards.
4. What is the warranty period for the equipment?
Warranty periods follow manufacturers’ standards:
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Solar panels: 12–15 years (performance warranty up to 25 years)
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Inverters: 5–10 years
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Accessories: 5 years
All systems include 24/7 remote monitoring.
5. How long does it take to break even?
It depends on consumption needs.
On average, households achieve payback within 4–5 years, while businesses typically reach payback in 3–4 years.
For the zero upfront cost (PPA) model, customers do not need to recover capital since they make no initial investment.
6. Does the system work during a power outage?
Standard on-grid systems automatically shut down during outages to ensure safety.
However, if customers choose a hybrid system or install battery storage, the system can continue operating normally.
7. Will installation damage the roof?
Thinh Phong uses specialized mounting clamps, waterproof gaskets, and non-penetrating fasteners to protect roof integrity.
Before installation, the technical team conducts a detailed assessment of each roof type.
8. How often should the system be cleaned and maintained?
Solar panels should be cleaned every 2–3 months, depending on dust levels.
General maintenance is recommended every 6–12 months to inspect wiring, grounding, the inverter, and overall system performance.
9. How much does installation cost?
Costs depend on system size and roof conditions.
Typical household installations range from 12–20 million VND per kWp, while businesses range from 10–15 million VND per kWp.
Customers may also choose the no upfront cost model through system leasing or PPA.
10. What is the implementation process?
According to Thinh Phong, the full process consists of six steps:
survey – solution consultation – contract signing – installation – commissioning – monitoring & periodic maintenance.
The company commits to ensuring technical standards and on-time delivery throughout the project.
Conclusion
Rooftop solar has become an economical, sustainable, and safe energy solution.
The answers above provide customers with a clearer understanding before choosing to invest or adopt renewable energy service packages.
Thinh Phong is currently one of the trusted providers offering various rooftop solar models for both households and businesses aiming to optimize costs and support green development.
