Ask ten specific questions before you sign anything, and you’ll know within minutes whether a solar installer is worth your rooftop. The questions to ask solar installer before signing contract that matter most cover equipment brand, separate warranties for panels and inverter, who files your subsidy paperwork, and what happens if the system underperforms. Vague answers to any of these are your cue to walk.
Key Takeaways
- Separate warranties matter: panels, inverter, and battery each need their own written warranty period; a single vague “5 year warranty” line may mean workmanship isn’t covered at all.
- Subsidy filing should be end-to-end: a vendor registered under PM Surya Ghar Muft Bijli Yojana should handle your application and KSEB net-metering liaison, not hand you a form and disappear.
- Ask for the design, not just a quote: a price without a site survey, shadow analysis, and line diagram is a guess dressed up as a proposal.
- Payment should follow milestones: full upfront payment before any equipment reaches your roof is one of the clearest signs of a bad installation company.
- Check credentials directly: ISO certification, MNRE empanelment and PM Surya Ghar vendor registration are verifiable; ask to see the certificates, not just hear the acronyms.
Quick-Reference: Questions and Red Flags at a Glance
| Question Category | What a Good Answer Sounds Like | What a Concerning Answer Sounds Like |
|---|---|---|
| Equipment brand | Names exact panel/inverter model, shares datasheet | “Branded panels” with no model number |
| Panel warranty | Product warranty and long-term performance warranty, both in writing | Verbal “long warranty” with no document |
| Workmanship guarantee | Written cover for leaks and wiring, with the term stated | No separate workmanship clause at all |
| Subsidy handling | Registered vendor files PM Surya Ghar and net-metering end-to-end | “You submit the forms yourself” |
| Site survey | Physical visit, shadow study, design diagram | Quote given over phone, no visit |
| After-sales AMC | Monitoring app and a defined response time | “Call us if there’s a problem” |
| Payment schedule | Staged: advance, mid-project, on commissioning | Most or all of the cost demanded upfront |
| Credentials | Shows ISO, MNRE and portal-registration proof on request | Deflects or can’t produce documents |
A common story: a homeowner signs with an installer who quoted a number over WhatsApp without ever seeing the roof, and months later finds half the panels sit in partial shade all afternoon. That’s not rare, and it’s exactly the kind of thing these ten questions catch before a rupee changes hands.
1. What exact equipment brand and model will you install, and can I see the datasheet?
A trustworthy installer names the exact panel and inverter model, not just a category like “Tier-1 branded panels.” Ask for the datasheet showing efficiency rating, temperature coefficient, and degradation curve. If the answer stays vague, that’s your first red flag.
Kerala’s heat and humidity affect panel output differently depending on cell type. If you’re still deciding between monocrystalline and polycrystalline, our guide on how solar panels actually work at home breaks down the basics before you compare quotes.
Watch for installers who swap the quoted brand for a cheaper one at installation time. Get the model number written into the contract itself, not just mentioned in conversation. A written spec sheet protects you if a dispute comes up later.
2. What warranty covers the panels, inverter, and battery separately?
A solid answer separates three distinct warranties: a product warranty on manufacturing defects, a performance warranty guaranteeing output over the long term, and a separate battery warranty if you’re going hybrid. Each should have its own document.
A concerning answer bundles everything into one vague line like “five-year warranty on the system.” That phrasing almost never covers panel degradation over decades, and it says nothing about who replaces a failed inverter in year six.
Ask specifically: “If my inverter fails in year 4, who pays for the replacement part and who pays for the labour to install it?” The answer should name a party for each, not just one.
If you’re weighing hybrid systems with battery storage, our comparison on on-grid vs off-grid vs hybrid solar systems explains what warranty terms typically apply to each configuration.
3. Is there a separate workmanship guarantee for leaks, wiring, and mounting?
Yes, a serious installer should offer a written workmanship guarantee, with the term stated, covering roof penetration leaks, mounting structure integrity, and wiring quality separately from equipment warranties. Kerala’s monsoons make roof-sealing quality a real financial risk, not a minor detail.
A good answer describes the exact mounting method used for your roof type, sloped tile or flat concrete, and confirms in writing that any leak traced to the installation gets fixed at no cost within the guarantee period.
A concerning sign: the installer treats workmanship as “covered under the general warranty” without spelling out what that actually means for a monsoon leak at your specific roof junction. Get this in writing before the crew shows up with drills.
4. Who handles my PM Surya Ghar subsidy and KSEB net-metering paperwork?
The installer should handle your PM Surya Ghar subsidy application and KSEB net-metering liaison end-to-end, from portal registration to final approval, as a registered vendor. If they push that work back onto you, expect delays and possible rejection.
A good answer names the specific steps: vendor registration confirmation, document collection, portal submission, and follow-up with KSEB until the net meter is installed and approved. This should read as a service, not an afterthought.
A concerning answer sounds like “the subsidy process is separate, you’ll need to apply on your own.” Because document mismatches can delay subsidy applications, that’s a lot of paperwork risk to hand back to a first-time applicant.
5. How will you size my system, and can I see the site survey and CAD design?
Sizing should come from a physical site survey, a shadow analysis across the day, and a CAD three-line diagram, not a phone-based guess from your last electricity bill. Ask to see the actual design document before signing anything.
A good installer walks your roof, measures usable space accounting for water tanks and parapet shadows, and produces a yield projection tied to your specific load pattern. If you’re unsure how much space your home even needs, our piece on how many solar panels a 3-bedroom house needs is a useful starting reference before the survey.
A concerning sign: a quote arrives within an hour of a WhatsApp message, with no visit scheduled. Sizing without a survey is one of the clearest signs of a bad solar installation company in Kerala, and it usually shows up later as underperformance nobody can explain.
6. What after-sales support and AMC do you offer once the system is live?
A capable installer offers structured AMC with defined response times, not a general promise to “help if something goes wrong.” Ask what generation monitoring looks like, whether there’s an app, and how fast a technician responds to a fault ticket.
- Monitoring: Does the system flag underperformance automatically, or do you have to notice a high bill first?
- Cleaning schedule: Kerala’s dust and coastal salt air affect output; ask how often panels get cleaned under AMC.
- Response commitment: A good answer names a response time for a site visit after a fault report.
- HT-side servicing: For commercial and industrial sites, annual HT-side servicing should be part of the AMC scope, not billed separately without notice.
7. What happens if my system underperforms compared to the proposal?
A proper answer names a remediation process: the installer investigates via monitoring data, checks for shading or wiring faults, and corrects the issue at no extra cost if the shortfall traces back to their design or installation. This is your recourse clause, so get it written down.
Without this clause, you’re relying entirely on goodwill if your 5kW system starts producing like a 3kW one. Ask specifically what the proposal’s projected monthly generation figure is, in units, so you have a number to hold them to later.
A concerning answer treats the proposal’s savings estimate as “just an approximation” with no follow-up commitment. Estimates should come from a genuine PV simulation, and installers who stand behind their numbers usually say so directly.
8. Can I see your certifications and past installation references?
Ask to see the actual ISO certificate, MNRE empanelment and registration proof, not just hear the acronyms recited. A vendor also needs registration under PM Surya Ghar Muft Bijli Yojana to file your subsidy claim at all.
Track record matters too. An installer with a genuine multi-year history across residential, commercial, and industrial rooftops in South India, including scaled commercial work, gives you more confidence than one that only started operations recently. SOLAR CONNECT, for instance, is a registered vendor on the PM Surya Ghar portal with more than 2,000 installations across Kerala, and certificates are available on request.
A concerning sign: hesitation or deflection when you ask to see the paperwork itself. These are public, verifiable credentials, and any legitimate EPC firm should produce them without friction.
9. What is the payment schedule, and is it tied to project milestones?
A fair payment schedule breaks into stages: a booking advance, a payment on material delivery, and a final payment after commissioning and net-meter approval. This protects you if the installer disappears mid-project or delivers late.
A concerning answer demands 80-100% of the total cost upfront before any equipment reaches your site. That level of upfront exposure leaves you with almost no leverage if the installation quality, timeline, or paperwork later falls short.
Get the payment schedule written into the contract with dates or milestones attached, not left as a verbal understanding. If the installer resists putting this in writing, treat that resistance itself as information.
10. What financing options do you support if I need a loan?
A helpful installer can point you toward bank loans and walk you through the paperwork those loans require, since subsidy timing and loan disbursement often need to line up. This support saves weeks of confusion for first-time buyers.
Ask whether they’ve worked with your specific bank before, and whether they can provide the technical proposal document banks typically ask for as part of a loan application. An installer with genuine lending relationships speeds this step up considerably.
Use a free online solar calculator before your loan conversation, so you walk in with a realistic sense of system size, savings, and payback period based on your actual KSEB tariff slab.
Frequently Asked Questions
What documents should I have ready before signing a solar contract?
Have your latest KSEB bill, property ownership proof, Aadhaar, and bank passbook copy ready, since these feed both the contract and the subsidy application. Missing or mismatched documents can delay the subsidy after signing.
Can I cancel a solar contract after signing?
Cancellation terms vary by contract, and many tie them to the advance payment. Read this clause carefully before signing, and ask the installer to explain it in plain terms if it isn’t clear.
How long should I expect between signing and switch-on?
A typical rooftop project runs several weeks from contract signing to switch-on, depending on system size, roof complexity, subsidy paperwork and the KSEB steps. We aim for about 30 days from consultation to commissioning where the roof and approvals allow. Larger commercial and industrial projects take longer.
Should I get multiple quotes before signing?
Yes, comparing two or three detailed proposals, each including a site survey and CAD design, helps you spot inconsistent sizing or missing warranty terms. A quote without a survey isn’t a real basis for comparison at all.
Getting these ten answers in writing before you sign turns a sales pitch into an accountable contract. If you’d like to compare a properly surveyed proposal against what you’ve been quoted elsewhere, get a free quote and site visit from SOLAR CONNECT, or see your numbers first with our free savings calculator.