B&B Green Energy Solar Guide
Rooftop Solar Installation in Kerala: A Complete 2026 Guide
Learn about system types, roof needs, subsidy support, net metering, and the installation process. Use this guide before you invest in rooftop solar for your home or business.
Start with the basics
How Rooftop Solar Works
A rooftop solar system turns unused roof space into a source of clean power. Solar panels capture sunlight and produce electricity. The inverter converts this power so it can run lights, appliances, pumps, air conditioners, and other equipment.
During the day, the building uses solar power first. If more power is needed, the balance comes from the grid. With an approved on-grid system, extra solar power can be sent to the grid through a bi-directional meter.
Good solar design starts with your electricity bill—not a fixed package. Your power use, sanctioned load, shade-free roof area, and future needs should decide the system size.
Choose the right configuration
Types of Rooftop Solar Systems
The best system depends on grid reliability, backup needs, budget, and how you use electricity during the day.
On-grid solar system
Connected to the electricity grid and mainly used to reduce bills. It normally does not provide backup during a power cut because the inverter shuts down for safety.
Off-grid solar system
Uses batteries and works without the grid. It can suit remote properties or selected backup loads. Batteries add cost, need space, and may need replacement later.
Hybrid solar system
Combines solar, grid power, and battery storage. It provides backup and more control over energy use. It usually costs more than a standard on-grid system.
Plan capacity correctly
How Much Roof Space Do You Need?
A site survey is important because roof shape, panel size, access, tilt, and shade can change the usable area. The figures below are only planning estimates, not a final design.
| System capacity | Indicative shade-free area | Indicative daily generation* | Often suitable for |
|---|---|---|---|
| 1 kW | 80–100 sq. ft. | About 4 units | Low-consumption homes or selected daytime loads |
| 2 kW | 160–200 sq. ft. | About 8 units | Small households |
| 3 kW | 240–300 sq. ft. | About 12 units | Many medium-use homes |
| 5 kW | 400–500 sq. ft. | About 20 units | Larger homes, offices or higher daytime use |
| 10 kW | 800–1,000 sq. ft. | About 40 units | Large residences and small commercial buildings |
*Planning estimate based on about 4 units per installed kW per day. Actual output changes with location, season, shade, roof direction, temperature, equipment, and system losses.
Know what affects your quote
What Affects Rooftop Solar Cost?
System size alone does not decide the final price. A good quotation should clearly list brands, ratings, warranties, safety equipment, mounting structure, approvals, and after-sales service.
- Solar panel type, efficiency and warranty
- Inverter type, capacity and monitoring
- On-grid, off-grid or hybrid configuration
- Battery chemistry and storage capacity
- Roof type and mounting structure
- Cable length and electrical protection
- Earthing and lightning protection
- Access, transport and installation complexity
- Net-metering and documentation scope
- Maintenance and service coverage
From survey to commissioning
Rooftop Solar Installation: Step by Step
Electricity-use assessment
Review recent bills, daytime power use, sanctioned load, tariff, and future needs such as air conditioning, water heating, or EV charging.
Roof and shadow survey
Measure the usable roof, check the structure, identify shade, and keep safe access for cleaning and repairs.
Engineering and proposal
Choose the system size, panel layout, inverter, mounting structure, safety equipment, earthing, and cable routes. The proposal should clearly list products and warranties.
Utility and subsidy documentation
Complete the required registration, feasibility check, consumer documents, and subsidy steps before installation when prior approval is needed.
Mechanical and electrical installation
Install the mounting structure, solar panels, inverter, cables, isolators, distribution boxes, surge protection, earthing, and monitoring equipment.
Testing and commissioning
Check wiring, insulation, safety devices, inverter operation, monitoring, and labels before connecting an approved on-grid system.
Net meter and handover
After utility inspection and approval, the required meter is installed. The owner should receive warranties, drawings, approvals, login details, and a maintenance schedule.
Residential financial support
Solar Subsidy and Net Metering in Kerala
Eligible home owners may receive Central Financial Assistance under PM Surya Ghar: Muft Bijli Yojana. Approval depends on current scheme rules, approved equipment, vendor requirements, and successful commissioning. B&B Green Energy currently highlights residential subsidy support of up to ₹78,000.
KSEB net metering allows an eligible rooftop solar system to supply the building and send extra power to the grid. The meter records both imported and exported power. Feasibility, documents, and settlement follow the rules in force at the time of application.
Important: Subsidy amounts, eligibility, and utility rules can change. Check the latest PM Surya Ghar and KSEB e-Kiran requirements before placing an order.
Prepare these details before applying
- Latest electricity bill and consumer number
- Applicant identity and address documents
- Bank details matching the eligible applicant
- Property ownership or authorised-use documents
- Clear photographs of the proposed roof
- Sanctioned load and recent consumption history
Protect long-term performance
What a Good Rooftop Solar System Should Include
Proven components
Use traceable solar panels, a correctly sized inverter, and products with clear manufacturer warranties.
Structural safety
Use a strong mounting structure suited to the roof, local weather, corrosion risk, and safe maintenance access.
Electrical protection
Use correctly rated cables, connectors, isolators, MCBs, surge protection, earthing, and lightning protection where needed.
Monitoring and service
Include generation monitoring, proper handover documents, and reliable after-sales support for cleaning, inspections, and faults.
Avoid expensive mistakes
Questions to Ask Your Solar Installer
- How was the recommended capacity calculated from my bills?
- Has shading across different seasons been considered?
- Which exact panel, inverter and protection brands are included?
- What are the product, performance and workmanship warranties?
- Does the quotation include structure, earthing and surge protection?
- Who will handle subsidy and net-metering documentation?
- What generation estimate is realistic for my roof?
- What maintenance is included after commissioning?
- Who responds locally if the system stops generating?
Signs of a dependable proposal
- Site-specific panel layout
- Itemised scope and model details
- Realistic—not guaranteed—generation estimate
- Clear approval responsibilities
- Documented safety components
- Written service commitment
Turn your roof into an energy asset
Get a site-specific rooftop solar proposal
B&B Associates, operating as BandB Green Energy Solutions Pvt Ltd, provides rooftop solar assessment, design, installation, documentation, and after-sales support for homes and businesses.
Frequently asked questions
Rooftop solar installation FAQs
How many units does a 1 kW rooftop solar system generate?
A common planning estimate in Kerala is about four units per day for each installed kW. Actual output changes with season, shade, roof direction, panel type, temperature, and system losses.
How much roof space is required for a 3 kW solar system?
A 3 kW system usually needs about 240–300 square feet of usable, shade-free roof area. The exact space depends on panel size, layout, setbacks, obstacles, and maintenance access.
Will an on-grid solar system work during a power cut?
A standard on-grid inverter normally shuts down during a power cut for safety. Backup power requires a properly designed hybrid or battery system.
Is rooftop solar suitable for Kerala’s monsoon climate?
Yes. The system should use a strong structure, corrosion-resistant materials, safe electrical work, good drainage, and proper earthing. Power generation will be lower during long cloudy or rainy periods.
Can I receive a subsidy for rooftop solar in Kerala?
Eligible home owners may qualify for Central Financial Assistance under PM Surya Ghar. This depends on current rules and successful completion of the process. Commercial and industrial systems may follow different rules, so check eligibility before buying.
How often should rooftop solar panels be cleaned?
Cleaning needs depend on dust, bird droppings, trees, road pollution, and rain. Watch system output and clean the panels safely when dirt starts to reduce performance.
How long do rooftop solar panels last?
Quality solar panels often come with long performance warranties, sometimes up to 25 years. Inverters and other system parts may need replacement sooner.
Kerala head office
Speak with B&B Green Energy
B&B Associates (BandB Green Energy Solutions Pvt Ltd)
35, A/VIII, Puthuppally, Kottayam, Kerala 686011
Phone: +91 99467 59777
Email: md@bbassociates.org
For location-specific service information, visit our rooftop solar installation in Kottayam page.