HOMEOWNER’S BUYING GUIDE · INDIA
Solar 101 India: How to Buy Rooftop Solar for Your Home
Start with your electricity bill, work out what fits your roof, and compare installed quotes before you commit. This guide walks through sizing, subsidy, net metering and the details that affect your bill.
1. What rooftop solar does
Panels produce DC electricity in sunlight. An inverter converts it to AC electricity your home can use. When the system is generating and your appliances are running, solar can supply part of their demand. At night, or when demand exceeds solar output, a typical on-grid home imports the balance from the grid. Surplus generation can be exported where the approved utility arrangement permits it.
A complete quote should cover panels, inverter, mounting, cabling, electrical protection, earthing, monitoring and installation. Ask who handles utility paperwork and what work carries a separate charge.
2. How to choose between 3 kW and 5 kW
- Start with 12 months of units. Include summer AC use and anticipated changes such as an EV or a new heat pump. The bill amount alone can hide changes in tariff or fixed charges.
- Estimate daytime use. A home with daytime AC, pumps or work-from-home loads can use more solar directly. Ask the installer to separate likely self-use and export.
- Measure the usable roof. Check shade from tanks, parapets, trees and neighbouring buildings. Ask for a layout that shows access for cleaning, drainage and future repairs.
- Check the connection. Give the installer your sanctioned load, single- or three-phase supply, and DISCOM details. Ask them to confirm the applicable capacity and approval rules.
Worked sizing example. If your home uses 3,600 units/year and a site assessment estimates 1,300 units per installed kWp per year, then 3,600 ÷ 1,300 ≈ 2.77 kWp. That makes a 3 kW-class quote worth comparing. This is a first-pass annual energy match. The design still depends on daytime use, shade, connection approval and how surplus is credited. The yield here is an example assumption.
3. Compare panels, inverters and backup
Panels
Ask for the manufacturer, exact model, module wattage and count. Multiply count × wattage ÷ 1,000 to get DC kWp. TOPCon describes a cell technology. Bifacial describes a module that can also collect light from its rear. Roof clearance and reflected light affect the rear contribution. Check the product warranty and power-performance warranty separately.
Inverter and mounting
Confirm the exact inverter model, AC output, phase, monitoring, and service contact. The installer should verify panel string voltages and currents against the inverter limits and size the mount for the roof and site conditions. Ask how anchors, cable routes and penetrations will be waterproofed and how the system will be commissioned.
Battery and power cuts
Standard on-grid solar shuts down during a grid outage. If backup is a priority, list the loads you need, their running and starting power, and how many hours you need them. Compare a compatible backup-capable inverter and battery by usable kWh, output kW, warranty and the circuits it will support. Ask for the backup price as a separate line. The examples below are on-grid kits.
4. Compare four actual Indian catalogue kits
These examples come from this website’s product catalogue. The price column uses the listed amount before any subsidy deduction. Ask for a current, itemised installation quote for your roof.
| Kit | Panels and DC size | Listed inverter | Catalogue amount before subsidy | What to check |
|---|---|---|---|---|
| Exide 3kW Subsidy TOPCon | 5 × 600–610 Wp 3.00–3.05 kWp DC | Exide Aditya ADGT3K-1P | ₹2,25,000 | 3 kW class. Confirm exact module wattage and approved capacity. |
| Adani 3kW Subsidy TOPCon | 5 × 550–580 Wp 2.75–2.90 kWp DC | Polycab PSIS-3K6 | ₹2,25,000 | 3 kW class label, but the listed array is below 3 kWp. Ask for a capacity-based subsidy calculation. |
| Vikram 5kW Subsidy TOPCon | 9 × 580 Wp 5.22 kWp DC | Growatt MOD 5000TL3-X2 (Pro) | ₹3,30,000 | 5 kW class with a three-phase inverter. Confirm your connection and exact inverter variant. |
| Adani 3kW Non-Subsidy TOPCon | 5 × 600–610 Wp 3.00–3.05 kWp DC | Polycab PSIS-3K6 | ₹1,65,000 | Non-DCR comparison. The catalogue lists no scheme subsidy. |
5. PM Surya Ghar subsidy and net metering
For eligible individual residential systems, the standard central subsidy schedule is ₹30,000 per kW for the first 2 kW and ₹18,000 per kW for additional eligible capacity up to 3 kW. The standard cap is ₹78,000. Confirm the applicable amount, qualifying configuration, documentation and vendor registration through the scheme and your DISCOM before ordering.
DCR is the domestic content requirement. For a subsidy quote, ask for the exact eligible module and documentation for domestically manufactured cells and modules, plus any applicable listing requirements. A brand name, a pincode or a kit label cannot establish eligibility by itself.
For a grid-connected installation, confirm who submits the application, arranges inspection, completes meter formalities and provides commissioning documents. The treatment of exports depends on the local metering arrangement and applicable tariff. Check how credits appear on the bill and how unused credits are settled.
PM Surya Ghar national portal · BESCOM rooftop solar portal · TGSPDCL solar net meter registration
6. Estimate installed cost, savings and payback
Compare the complete installed price before subsidy, including taxes and any charges for mounting height, extra cable, waterproofing, protection, approvals or meter work. Ask when each payment is due and when any approved subsidy would be credited. A lower net estimate can still require a larger payment upfront.
Illustrative savings calculation. Assume 4,000 kWh/year generated, with 2,800 kWh used at home and 1,200 kWh exported. If the avoided energy charge is ₹8/kWh and export value is ₹3/kWh, the estimated annual value is (2,800 × ₹8) + (1,200 × ₹3) = ₹26,000. At a hypothetical net installed cost of ₹1,50,000, simple payback is about 5.8 years before finance, maintenance and replacement costs. These are worked assumptions. Use your actual tariff, export terms and an installer’s roof-specific generation estimate.
Ask to see the same calculation under lower generation or self-consumption. Fixed charges may continue. If you use financing, compare the total repayment, fees and monthly instalment with expected bill savings. Include maintenance and any likely inverter or battery replacement in longer-term comparisons.
7. What to ask before signing a solar quote
- Exact panel and inverter models, array kWp, inverter AC kW, and a roof layout.
- Expected first-year generation, the assumptions behind it, and a breakdown of self-use and export.
- Itemised installed price, exclusions, payment milestones and estimated subsidy shown separately.
- Who handles portal work, meter approval, commissioning, and any follow-up with the DISCOM.
- Panel, inverter and workmanship warranties, local service contacts and how to raise a claim.
After commissioning, collect the final bill of materials, warranty papers, meter and commissioning records, safety instructions and monitoring access. Check the first few bills against your generation readings and raise unexplained differences with the installer or utility.
8. Frequently asked questions
Will a 3 kW solar system run my whole house?
It depends on how much power your appliances draw at the same time and when you use them. An on-grid system can supply part of your demand while the grid supplies the balance. Compare annual consumption, daytime usage, and inverter output before choosing a size.
What is the difference between kWp and units?
kWp is the rated peak DC capacity of your solar panels under standard test conditions. A unit on an electricity bill is one kilowatt-hour (kWh), a measure of energy. A 1 kW appliance running for one hour uses 1 kWh.
Can I get ₹78,000 subsidy on every 3 kW kit?
The figure is the standard central cap for eligible individual residential installations at the qualifying capacity. A 3 kW kit label alone does not establish the approved capacity or eligibility. Confirm the module count, wattage, DCR documentation and scheme approval.
Will rooftop solar work during a power cut?
A standard grid-tied inverter shuts down during a grid outage. If you need backup, ask for a compatible inverter with a dedicated backup output, storage sized for the loads, and a design that safely isolates those circuits from the grid.
How much roof space do I need?
It depends on the exact module dimensions, setbacks, shading, access and mounting layout. Ask for a scaled layout showing panel rows, clearances and service access before paying a deposit.
Should I buy 3 kW or 5 kW?
Compare both against the same 12 months of consumption and the same roof assessment. A larger system can make sense if you can use or obtain appropriate credit for the extra generation and your connection and roof allow it.
Sources and catalogue notes
Equipment and catalogue amounts are a snapshot of the website’s products.js. System sizing, savings and financing examples are illustrative. Check current scheme and utility requirements for your address.