Direct answer: Before installing home solar, ask how capacity was calculated, how many panels fit safely, expected monthly generation, outage behaviour, subsidy and net-metering eligibility, maintenance, separate product and performance warranties, savings assumptions and who owns approvals and service. Written answers should form part of the proposal or contract. Every important answer should be supported by bills, a measured layout, technical documents, current official rules or a written contractual commitment.
Introduction
Homeowners repeatedly ask the same first questions about roof area, panel count and direction, but a safe purchase also requires answers about bills, outages, subsidy, net metering, maintenance, warranties and service. This guide brings those decisions into one place. It uses calculations only as illustrations, explains where local rules change the answer and ends with a written-information checklist to use when comparing installers.
Quick Takeaways
- Capacity should follow annual consumption, not panel count alone.
- Roof area estimates must include access and setbacks.
- Standard on-grid solar shuts down during outages.
- Savings require tariff, generation and self-consumption assumptions.
- Written warranty, approval and service responsibilities protect the buyer.
Home solar questions at a glance
Question | Evidence to request | Red flag |
|---|---|---|
How was size chosen? | 12-month consumption calculation | Sized from one bill |
Will it work in outage? | System architecture/load list | Unqualified yes |
What will I save? | Assumptions and sensitivity | Guaranteed percentage |
Who gets approvals? | Written responsibility matrix | Verbal promise |
What is warranted? | Separate certificates | One vague “25-year warranty” |
Here are answers to five common questions about residential solar systems.
1. How Many Solar Panels Can Fit on My Roof?
The number depends on the usable roof area and the dimensions of the selected modules. Panel sizes vary according to their wattage, technology and manufacturer.
The layout must also provide space for:
- Maintenance walkways
- Gaps between panel rows
- Roof-edge clearances
- Water tanks and other obstructions
- Safe cleaning and inspection
A professional solar site survey can identify the shadow-free area and determine how many panels can be installed safely.
2. How Much Roof Space Is Required?
A 1 kW rooftop solar system generally requires around 10 square metres of shadow-free area. The actual requirement varies with panel efficiency, module placement, roof layout and safety clearances.
High-efficiency solar panels may fit more capacity into a smaller area. Learn more about solar-panel size and roof space.
3. How Many Solar Panels Do I Need?
The approximate panel count can be calculated using:
Required system capacity in watts ÷ individual panel wattage
For example, a 5 kW system using 500-watt panels would require approximately 10 panels.
The appropriate system capacity also depends on electricity consumption, daytime usage, sanctioned load, roof space, budget and local net-metering rules. Use the Freyr Energy solar calculator for an initial estimate.
4. How Can I Maximise Solar-Panel Output?
To support reliable solar generation:
- Minimise shadows on the panels.
- Select a suitable direction and tilt.
- Clean panels when dirt accumulates.
- Monitor system performance.
- Use compatible panels and inverters.
- Arrange periodic professional inspections.
Water tanks, trees, lift rooms, antennas and nearby buildings can cast shadows and reduce output. Follow appropriate solar-panel cleaning practices to avoid damaging the modules.
5. Which Direction Should Solar Panels Face in India?
South-facing panels generally provide strong annual generation in India. However, east- and west-facing panels can also perform effectively.
- East-facing panels: Favour morning generation.
- West-facing panels: Produce more electricity during the afternoon.
- South-facing panels: Generally provide balanced annual output.
The ideal direction and tilt depend on the roof, shading, latitude, local weather and household consumption pattern.
Read more: Solar Panel Direction as per Vastu: Which Direction Is Best for Your Home?
The Tenth Question: What Will the System Cost and Save?
A responsible answer begins with the gross installed price and an itemised scope. Government solar subsidy, state incentive, vendor offer and financing must appear separately. Savings depend on site-specific generation, self-consumption, import tariff, export credit and charges that remain. Ask for the assumptions behind the first-year estimate and a conservative case that includes degradation, maintenance and likely major replacements.
Question | Evidence behind the answer | Warning sign |
|---|---|---|
How was capacity chosen? | Twelve months of bills and daytime-load analysis | Sized only from roof area or maximum subsidy |
How many panels fit? | Measured layout with setbacks, shade and access | Panel count based only on total square feet |
How much will it generate? | Location-specific simulation and stated losses | A guaranteed units-per-day claim |
What happens in an outage? | Single-line diagram and backup-circuit schedule | “Solar works in daylight” without anti-islanding explanation |
What will it cost? | Itemised models, work, taxes and exclusions | One final price with no bill of materials |
What will it save? | Self-use, tariff and export assumptions | Guaranteed zero bill or fixed payback |
Who handles approvals? | Written responsibility matrix | Verbal assurance without documents |
What is warranted? | Separate product, performance and workmanship terms | One combined “25-year warranty” statement |
Questions About Roof, Shade and Direction
South-facing modules at an appropriate tilt can be a useful starting point in India, but east-west layouts may fit more capacity or better match morning and afternoon loads. The best layout depends on latitude, roof shape, shade, wind, access and the consumption profile. A shade-free direction is usually more valuable than a theoretically ideal orientation obstructed by tanks or neighbouring buildings.
Questions About Outages and Batteries
A normal on-grid system shuts down during a utility outage. If backup is required, identify the critical circuits, maximum simultaneous power and required hours. Then size the compatible hybrid inverter and usable battery energy. Do not assume a battery “for 5 kW solar” will run every household appliance or a large air conditioner.
Questions About Ownership and Service
- Who owns the roof and electricity connection, and are society, landlord or lender permissions required?
- Who files portal and DISCOM documents, pays fees and responds to objections?
- Who monitors alarms, cleans the array, performs preventive inspections and replaces failed equipment?
- What happens to warranties and monitoring if the installer or manufacturer changes?
- How will modules be removed and reinstalled for roof repairs or property redevelopment?
- Which drawings, serial numbers, certificates, logins and service contacts are provided at handover?
The Written-Answer Rule
Every important answer should appear in the proposal, contract, drawing, datasheet or warranty, not only in a conversation. Compare providers using the same written checklist. Where an answer depends on subsidy, tariff or DISCOM policy, verify the current official rule and record the date checked.
Panel Count and Roof-Area Example
A 5 kW target using 500 W modules suggests ten modules by simple division. If each module is roughly 2.2 m by 1.1 m, the module footprint alone is about 24.2 sq. m. The required usable roof is larger after safe clearances, access, row spacing, tilt, parapets and obstructions. The exact datasheet dimensions and measured layout must replace this illustration.
Generation and Savings Example
If a proposed system is expected to generate 6,000 units a year and the home directly uses 4,200 of them, those self-consumed units are valued at the avoided import tariff. The remaining 1,800 exported units are valued under the applicable settlement rule. Fixed charges may remain. This split is more credible than multiplying all 6,000 units by the highest tariff on the bill.
What to Keep After Installation
- Final layout, single-line diagram and approved capacity.
- Module and inverter models, serial numbers, invoices and datasheets.
- Product, performance and workmanship warranty documents.
- Test results, commissioning certificate and meter/interconnection records.
- Subsidy application and payment records where applicable.
- Monitoring credentials, baseline estimate and service contacts.
- Safe cleaning, shutdown, roof-access and maintenance instructions.
Twenty Questions Before Installation
Decision area | Questions to answer before purchase |
|---|---|
Consumption and size | What are 12-month units? What daytime/future loads matter? How was capacity calculated? |
Roof and layout | What area is usable? What shade exists? Are access, drainage and fire paths preserved? |
System behavior | What happens by day, night and outage? Which loads receive backup? |
Equipment | What exact module, inverter, structure and protection models are included? |
Approvals | Who handles portal, subsidy, feasibility, meter and inspection? |
Economics | What is gross price? What assumptions drive generation, savings and payback? |
Warranty/service | Who issues each warranty? Who responds, at what cost and on what timeline? |
Handover/future | What records are delivered? How are roof repair, expansion, sale and end of life handled? |
Home Solar Evidence Checklist
Claim | Minimum evidence |
|---|---|
“This size is right” | Bills, load analysis, roof layout and approval limits |
“It will generate X units” | Location-specific simulation with losses and assumptions |
“It will save ₹X” | Self-use, tariff, export credit, charges and recurring cost |
“Subsidy is available” | Current official eligibility and portal/DISCOM process |
“It has 25-year warranty” | Separate product and performance warranty documents |
“It gives backup” | Hybrid SLD, protected-load schedule, kW and usable kWh |
“Everything is included” | Itemised scope, taxes, fees and exclusions |
Worked Sizing and Savings Chain
Start with annual units, choose a target share, divide by a site-specific annual yield, then test the resulting capacity against safe usable roof area and local approval limits. Model generation as self-consumed and exported units. Apply the avoided import tariff to self-use and the applicable credit to export. Subtract recurring cost and keep subsidy timing separate from project performance.
Questions That Remain After Commissioning
- Does monitoring match the expected seasonal pattern?
- Do meter import/export registers and the first full bill reconcile?
- Who receives and closes inverter or generation alarms?
- When should cleaning or inspection occur based on actual site conditions?
- Where are drawings, serial numbers, warranties, approvals and service records stored?
- How will the system be isolated for roof work or an emergency?
Conclusion
Homeowners can make a confident solar decision when every important answer is tied to evidence: bills for sizing, a roof survey for layout, datasheets for equipment, current rules for subsidy and net metering, and written documents for warranties and service. Use calculations as starting points, not guarantees. A proposal that explains limitations is more trustworthy than one that promises a zero bill. Keep the final checklist and compare providers on the same scope before paying an advance.