Two quotations for a 3 kW system. One says Rs 1,45,000, one says Rs 1,75,000. The cheaper one looks like the obvious choice.
It might be. It might also be the same system with worse everything. The quotation tells you which — if you know what to look for.
1. Panels: brand, model, wattage, quantity
Should say: "6 x 545W Mono PERC, [brand], model [number]"
Warning sign: "3 kW high efficiency panels"
Ask for:
- Brand and model number
- Wattage per panel and how many
- Cell type — mono PERC, TOPCon, polycrystalline
- Whether they are DCR (domestic content) panels, which subsidy schemes may require
Multiply wattage by quantity and check it actually reaches the system size you are paying for. 6 x 545W is 3,270W — a genuine 3 kW. 5 x 545W is 2,725W, and someone is selling you a 2.7 kW system labelled 3 kW.
2. Inverter: brand, model, capacity, type
Should say: "1 x 3 kW on-grid inverter, [brand], model [number], with Wi-Fi monitoring"
Warning sign: "3 kW inverter"
The inverter is the component most likely to fail first and the one most often quietly downgraded. It is also the piece that determines whether you can see what your system is doing.
- Is it on-grid, hybrid or off-grid? These are different prices and different capabilities.
- Does it have monitoring? Without it you will not notice for months if output drops.
- What is the warranty — 5 years, 7, 10?
3. Mounting structure
Should say: material, galvanisation, and whether it is standard or raised
Warning sign: "MS structure"
Plain mild steel rusts. On a roof, in Indian weather, it rusts faster than you expect. Ask for hot dip galvanised or aluminium, and get the height written down if you wanted a raised structure.
4. Cables, protection and earthing
This section is where the cheapest quotes save money, because nobody inspects it and nothing visibly fails for years.
Look for:
- DC cable specification — solar-rated, UV resistant
- DCDB and ACDB (the protection boxes)
- Earthing — how many electrodes
- Lightning arrester
5. Net metering and paperwork
Ask directly:
- Is the net meter cost included, or billed separately?
- Does the vendor handle the DISCOM application, or is that your job?
- Does the vendor file the subsidy claim on the portal?
- What happens if the DISCOM rejects the application?
Vendors who handle the paperwork usually charge a bit more and are usually worth it. The process involves multiple steps with a body that does not answer the phone quickly.
6. Warranties — three separate ones
| Item | Typical | What it covers |
|---|---|---|
| Panel product | 10 – 12 years | Manufacturing defects |
| Panel performance | 25 years | Output stays above a stated level |
| Inverter | 5 – 10 years | The unit itself |
| Workmanship | 1 – 5 years | The installation |
7. What is excluded
Ask what is not included. You will get a shorter and more honest answer.
Commonly excluded:
- Civil work — foundation pedestals for the structure
- Cable run beyond a stated length, if the inverter is far from the meter
- Any roof strengthening
- Net meter charges
- Cleaning and maintenance after the first year
8. Payment schedule
A reasonable schedule looks like:
Do not pay in full before commissioning. Keep the last part until the system is actually generating and the net meter is in.
The vendor question that matters most
Comparing two quotes properly
Put them side by side on these lines only:
- Total panel wattage — the real system size
- Panel brand and cell type
- Inverter brand, type and warranty
- Structure material and height
- Earthing and lightning protection — present or absent
- Who does the paperwork
- What is excluded
Once those are on the same basis, the price difference usually explains itself. Sometimes the cheaper quote is genuinely better value. More often it is a smaller system with thinner components and the safety items removed.
A worked comparison
Two quotes for what both call a 3 kW system:
| Quote A | Quote B | |
|---|---|---|
| Price | Rs 1,45,000 | Rs 1,75,000 |
| Panels | 5 x 550W = 2,750W | 6 x 545W = 3,270W |
| Panel type | "High efficiency" | Mono PERC, brand named |
| Inverter | "3 kW on-grid" | Brand, model, 7 yr warranty |
| Structure | "MS structure" | Hot dip galvanised |
| Earthing | Not mentioned | 2 electrodes, itemised |
| Lightning arrester | Not mentioned | Included |
| Paperwork | "Customer to arrange" | Vendor handles |
| Actual cost per watt | Rs 52.7 | Rs 53.5 |
On price per watt the two are almost identical. Quote A is not cheaper — it is smaller. And it omits earthing, lightning protection and the paperwork, all of which you will pay for separately or go without.
Warning phrases and what they usually mean
| What the quote says | What it often means |
|---|---|
| "High quality panels" | Brand not decided, or not one they want to name |
| "Branded inverter" | Whichever brand is cheapest at purchase time |
| "As per site condition" | Will be billed extra later |
| "Standard accessories" | Undefined, so unenforceable |
| "Subsidy will be arranged" | Check whether they are actually on the portal |
| "25 year warranty" | Performance warranty, not product warranty |
| "Turnkey solution" | Ask what is excluded — the answer is never nothing |
After installation, before final payment
Do not release the last payment until you have checked these:
- Count the panels and check the model number on the back matches the quote
- Photograph the inverter serial number and confirm it is the model quoted
- Check the structure is the material and height agreed
- Confirm earthing electrodes are physically installed, not just billed
- Inspect every roof penetration for proper sealing
- Watch the inverter display generating on a sunny day
- Get the monitoring app configured in your name, not the installer's
- Collect all warranty certificates in your name
Questions people ask
The vendor says brands cannot be fixed because of availability. Is that reasonable?
Partly. Ask for a shortlist of two or three acceptable brands per item rather than one. That gives him flexibility and gives you a floor.
How much should a 3 kW system cost per watt?
Roughly Rs 45 to Rs 60 per watt for a normal on-grid system before subsidy. Below Rs 40 is worth questioning closely.
Should I buy panels and hire an installer separately?
Usually not. Subsidy requires a registered vendor doing the installation, and splitting it means nobody owns the warranty when something fails.
Is the cheapest registered vendor safe?
Registration means they can process the subsidy. It is not a quality certification. Ask for two local installations you can visit, ideally a couple of years old.