Solar Buying Guide :-
Buying a rooftop solar system is one of the smartest long-term investments a homeowner can make — but it’s also an area where small mistakes can cost you thousands, reduce lifetime savings, or cause years of headaches. Below is a practical, SEO-friendly guide that explains the most common mistakes, why they matter, how to avoid them, worked examples, and authoritative links you can use to confirm facts and policy.
Quick TL;DR (for skimmers)
- Don’t pick the cheapest installer or lowest-price panels without checking specs, warranties and service.
- Do size the system from real monthly bills (not optimistic claims).
- Check roof condition, shading, orientation and tilt before buying.
- Verify net-metering/subsidy rules and application process with your DISCOM and MNRE. Ministry of New and Renewable Energy+1
- Ask for brand names, datasheets, degradation rate and conditional warranty in writing. Use independent research (NREL, PV-magazine) on degradation and longevity. NREL+1
1) Buying a system that’s the wrong size (too small or too big)
Why it’s a mistake: Undersized systems leave you buying the same grid electricity you wanted to avoid. Oversized systems mean higher upfront cost, and in many places excess export is not compensated well.
How to avoid it: Size the system from actual electricity bills. Use last 12 months of consumption to capture seasonality.
Worked example (step-by-step):
- Monthly consumption = 600 kWh.
- Daily average = 600 ÷ 30 = 20 kWh/day.
- In many Indian locations, a well-installed 1 kW system produces roughly 4 kWh/day (this varies with location; use local insolation numbers if available).
- Required system size = daily consumption ÷ production per kW = 20 ÷ 4 = 5 kW.
- So you’d target ~5 kW rooftop capacity (confirm with installer for rooftop shading/tilt losses).
Always show your bills to three installers and compare their generation estimates and assumptions (losses, tilt, orientation). If an installer quotes a much smaller size claiming “more efficient panels”, ask them to show the yield calculation.
2) Choosing equipment by price alone (cheap panels/inverters)
Why it’s a mistake: Solar is a long-term asset (25+ years). Low-quality panels can have faster degradation and poorer warranty support; cheap inverters may fail early. The effective cost is lifetime energy produced — not the upfront price.
What to check:
- Panel datasheet: power tolerance, temperature coefficient, nominal operating cell temperature (NOCT), fire rating, and linear degradation rate (e.g., 0.3%–0.8%/year). See NREL review on degradation. NREL+1
- Inverter: peak efficiency, European efficiency or CEC rating, warranty (5–12 years standard; extended options exist).
- Bankability & brand track record.
Example: Two panels rated 370 W:
- Panel A: 0.3%/yr degradation → after 25 years ≈ 93% of original output.
- Panel B: 0.8%/yr degradation → after 25 years ≈ 82.5% output.
That difference matters to lifetime yield and payback.
3) Not checking roof condition and mounting constraints
Why it’s a mistake: If your roof needs re-tiling or replacement in 1–3 years, installers may need to remove and re-install panels (costly). Roof strength, slope, and fire access also matter.
How to avoid it:
- Inspect and repair/replace the roof before installation if needed.
- Ask for a structural assessment and wind-load plan.
- For flat roofs, check available area and water drainage; for tiled roofs, confirm clamp and attachment methods.
4) Ignoring shading and poor layout planning
Why it’s a mistake: Even small shadows (chimneys, trees, water tanks) can reduce output drastically if panels are stringed incorrectly.
How to avoid it:
- Ask for a shade analysis (PVsyst or software simulation) or time-of-day shading diagram.
- Consider microinverters or optimizers when partial shading is unavoidable.
- Ensure panel layout minimises mismatch losses; avoid mixing different panel models on one string.
5) Not understanding warranties and what’s covered
Main warranties to check:
- Product warranty (physical defects; usually 10–25 years depending on brand).
- Performance warranty (e.g., 25 years guaranteeing ≥80–90% output).
- Inverter warranty (typical 5–10 years; extended warranties optional).
- Workmanship/installation warranty from the installer (usually 1–5 years).
Tip: Get warranty details in writing and verify how claims are handled (local service center, replacement policy, pro-rata terms).
6) Skipping due diligence on the installer (service & track record)
Why it’s a mistake: Many consumer complaints arise from poor after-sales support rather than the panels themselves. Regulatory action in some markets has followed large numbers of bad actors. TIME+1
Checklist for installer checks:
- Company registration, GST number, local office/technicians.
- References and recent installations (visit if possible).
- Insurance coverage and compliance certificates.
- Detailed contract: payment schedule, timelines, penalties, performance guarantees.
7) Not checking net-metering and subsidy rules (or missing documentation)
Why it matters: Subsidies and net-metering rules can significantly change your economics. Rules differ by state/DISCOM and change over time.
Action steps:
- Check the MNRE and your local DISCOM site for current rooftop policies and application steps. Apply through the official channel specified by your DISCOM or MNRE program if you want central/state support. Ministry of New and Renewable Energy+1
- Confirm net-metering policy: export limits, settlement period, timing and who installs the net meter.
8) Blindly accepting financing/lease terms without reading fine print
Why it’s a mistake: Solar loans, EMIs and leases have different implications. Some leases transfer responsibility for maintenance; loans mean you own the system. Hidden charges, prepayment penalties, or variable interest rates change the payoff.
How to avoid it: Get the full loan/lease contract, ask for all fees in writing, and compare effective interest rates (APR), early repayment terms, and service obligations.
9) Not planning for operations & maintenance (O&M)
Why it’s a mistake: Dust, bird droppings, and module soiling reduce yields. Inverter faults or wiring issues can drop performance.
Plan ahead:
- Ask for an O&M plan and pricing (annual cleaning, monitoring, quick response times).
- Install an online monitoring system with performance alerts.
10) Overlooking safety, standards, and end-of-life issues
Why it matters: Improper installations can violate local building/fire codes. Also plan for panel disposal or recycling at end-of-life. Government and research resources discuss best practices for safety and end-of-life handling. NREL+1
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