Why Rooftop Solar Makes Sense in India
Indian electricity tariffs are telescopic — the more you consume, the higher the rate on your last units. In Tamil Nadu, for example, TNEB's top domestic slab rate is ₹6.40/unit. Every unit solar offsets is a unit you stop paying that top rate for, which is why solar tends to pay back fastest for higher-consumption households. Combined with the PM Surya Ghar subsidy cutting a large chunk off the upfront cost, a well-sized rooftop system is one of the few home investments that pays for itself and then keeps paying.
Why This Calculator Is More Accurate
Most online solar calculators price your savings at a single flat, national-average electricity rate. That's not how Indian electricity actually works — each DISCOM sets its own telescopic slab tariff, and the units your solar system offsets are your most expensive units, at the top of your slab. This calculator computes your real bill before and after solar using your own DISCOM's published tariff — the exact same engine that powers our 36 state electricity bill calculators — so the savings you see here are grounded in your actual rate structure, not a generic assumption.
Calculate your solar payback
Solar ROI Calculator
Payback period and savings from a rooftop system
Payback period
4.33 yrs
then ~₹20,079.00/year saved
- System cost
- ₹1,65,000.00
- PM Surya Ghar subsidy
- −₹78,000.00
- Net cost
- ₹87,000.00
- Annual generation
- 4380 units
- Monthly savings
- ₹1,673.25
- 25-year net savings
- ₹4,14,975.00
Assumes ~4 units/kW/day generation and Southern Power Distribution Co. of AP (APSPDCL) tariff; actual output varies with location, shading and panel quality.
How solar payback is calculated
Savings on the expensive units first. Because Indian tariffs are telescopic, solar offsets your highest-priced slabs first. We compute your bill before and after solar using the real DISCOM tariff, so the savings reflect your actual marginal rate — not a flat average.
PM Surya Ghar subsidy. The central subsidy is ₹30,000/kW for the first 2 kW plus ₹18,000 for the 3rd kW, capped at ₹78,000. Net cost is the system price minus this subsidy — see the full breakdown and how-to-apply steps on our subsidy calculator.
Payback. Net cost ÷ annual savings gives the payback in years. Generation assumes ~4 units per kW per day; your actual output depends on location, roof orientation and shading.
On-Grid vs Off-Grid vs Hybrid — Which Fits Your Home
On-Grid (Grid-Tied)
Best for: Most urban and suburban homes with reasonably reliable grid supply
Pros
- + Lowest upfront cost of the three
- + Eligible for the PM Surya Ghar subsidy
- + Net metering exports surplus generation for a bill credit
Cons
- − No power during a grid outage (the inverter shuts down for safety)
- − No battery backup included by default
Off-Grid (Standalone)
Best for: Remote homes with no reliable grid connection at all
Pros
- + Fully independent of the grid
- + Keeps working during a grid outage
Cons
- − Not eligible for the PM Surya Ghar subsidy
- − Needs a large battery bank — significantly higher cost
- − Must be sized for worst-case usage, not average, since there's no grid to fall back on
Hybrid
Best for: Homes that want backup power during outages plus subsidy/net-metering benefits
Pros
- + Battery backup during outages
- + Still eligible for net metering and subsidy in most states
- + Automatically switches between grid, battery and solar
Cons
- − Higher upfront cost than a plain on-grid system
- − Hybrid inverter and battery add ongoing maintenance
25-Year Cost Comparison: Solar vs. Grid
How cumulative cost compares if your electricity tariff keeps rising — pick a scenario to see the effect:
| Year | Cumulative grid cost | Cumulative solar cost | Cumulative savings |
|---|---|---|---|
| Year 1 | ₹17,790.00 | ₹87,600.00 | -₹69,810.00 |
| Year 5 | ₹1,00,283.88 | ₹90,382.26 | ₹9,901.63 |
| Year 10 | ₹2,34,486.34 | ₹94,908.48 | ₹1,39,577.87 |
| Year 15 | ₹4,14,079.50 | ₹1,00,965.58 | ₹3,13,113.92 |
| Year 20 | ₹6,54,415.67 | ₹1,09,071.35 | ₹5,45,344.31 |
| Year 25 | ₹9,76,039.67 | ₹1,19,918.71 | ₹8,56,120.96 |
Assumes your electricity tariff rises 6%/year (base scenario) and solar generation stays constant. Real panels degrade gradually (commonly cited at ~0.5%/year), which would modestly reduce real-world savings versus this projection.
Common Myths About Rooftop Solar — Debunked
Myth: Solar panels don't generate anything on a cloudy or rainy day.
Fact: Panels still generate power from diffuse sunlight on overcast days — typically 10–25% of clear-sky output, not zero. Monsoon months do lower your monthly total, which is exactly why generation estimates use a full-year average, not a sunny-day best case.
Myth: Hailstorms and monsoon weather will damage the panels.
Fact: Standard rooftop panels are tested to withstand hail impact and heavy rain under the IEC 61215 certification most reputable brands carry. Physical damage from severe weather is uncommon and is typically covered under the manufacturer's product warranty.
Myth: Solar panels need constant cleaning and maintenance.
Fact: A rooftop system is largely low-maintenance — occasional cleaning (roughly monthly in dusty areas, less elsewhere) to clear dust buildup is the main upkeep. There are no moving parts in the panels themselves to service.
Myth: Installing solar will hurt my property's resale value.
Fact: A paid-off or subsidised rooftop system is generally viewed as a value-add by buyers, since it lowers the running cost of the home — the opposite of a liability, provided the installation is done to code with proper documentation.
Myth: Panels stop working properly in India's summer heat.
Fact: Panel output does derate slightly as cell temperature rises — a real, well-documented effect of the semiconductor physics — but this is already factored into standard generation estimates. It reduces efficiency somewhat; it doesn't stop the system from working.
6 Ways to Maximize Your Solar ROI
Orient panels south-facing where possible
A roughly south-facing, unshaded tilt captures the most sun through the day in the northern hemisphere — ask your installer to confirm the best orientation for your specific roof.
Choose an MNRE-empanelled installer
Empanelled vendors are required to meet quality and component standards to qualify for the subsidy — verify empanelment on the PM Surya Ghar portal before signing a quote.
Apply early in the financial year
Subsidy disbursal depends on budget allocation cycles — applying earlier reduces the chance of processing delays tied to year-end demand spikes.
Clean panels roughly monthly
Dust and pollen buildup gradually reduces output — a simple wipe-down (or asking your installer about an auto-cleaning add-on) keeps generation closer to its rated potential.
Consider a hybrid setup if outages are frequent
If your area has regular power cuts, a hybrid inverter with battery backup keeps essentials running when the grid goes down — a plain on-grid system won't.
Register for net metering promptly
Delaying your net-metering application means exported units aren't credited in the meantime — apply as soon as installation is complete, not after the first bill arrives.
Solar Financing Options
Interest rates and terms vary by lender and change over time — treat these as a starting point for comparison, not quoted rates.
PM Surya Ghar subsidised loan
Several public-sector banks offer a collateral-free loan scheme tied to the PM Surya Ghar programme, typically at a lower rate than an unsecured personal loan, for the net cost after subsidy.
Up to ~10 years
General solar/green loans
Many banks and NBFCs offer dedicated solar-purchase loans outside the government scheme, usually priced a little higher than the subsidised option but with fewer eligibility restrictions.
Typically 3–7 years
Personal loan
A regular unsecured personal loan works for any system size, but carries a higher interest rate than a purpose-built solar loan since it isn't backed by any scheme or asset.
Typically 1–5 years
RESCO / solar lease model
A third-party developer owns and maintains the system on your roof; you pay a fixed monthly amount for the power it generates, with no upfront cost — less common for small residential rooftops than for larger installations.
Usually 10–25 year contracts
Your Solar Impact
Estimated annual CO2 offset
3,592 kg
Roughly equivalent to
171 trees/year
Based on India's indicative national grid emission factor (~0.82 kg CO2/kWh, CEA CO2 Baseline Database) and a commonly cited average of ~21 kg CO2 absorbed per mature tree per year. Actual figures vary by report year, grid mix and tree species.
How Solar Powers Your AC
Air conditioning is usually the single biggest load in an Indian home, and it runs mostly during daylight hours — exactly when solar generates the most. If AC is a major part of your bill, size your system with that load in mind rather than just your average monthly units.
Related calculators
Frequently asked questions
How accurate is this solar payback estimate?
It prices offset units at your actual DISCOM tariff and applies the real PM Surya Ghar subsidy formula, so the ₹ figures are grounded in real rates. The generation assumption (~4 units/kW/day) is a conservative pan-India average — your real output depends on location, roof orientation, shading and panel quality, so treat this as a planning estimate, not a quote.
What generation assumption does this calculator use, and why?
Roughly 4 units per kW of installed capacity per day, averaged across a year. This is a commonly used conservative figure for Indian rooftop conditions — sunnier states or well-oriented, unshaded roofs typically generate more, so actual payback can be faster than shown here.
Does this account for panel degradation over 25 years?
No — the annual savings figure uses year-one generation held flat. Real panels degrade gradually (commonly cited at around 0.5% per year), which would modestly extend payback and reduce total lifetime savings versus the figure shown.
Do I need net metering for these savings to work?
Yes. Net metering is what lets your DISCOM credit you for solar units you export back to the grid, which is how the units-offset calculation in this tool actually gets realised on your bill. Your DISCOM/installer handles the net-metering application as part of installation.
What if I don’t get the full PM Surya Ghar subsidy?
The central subsidy follows a fixed formula (₹30,000/kW for the first 2 kW, ₹18,000 for the 3rd kW, capped at ₹78,000) and is not means-tested, but processing time and any additional state-level subsidy vary. Check your exact eligibility and amount on our PM Surya Ghar subsidy calculator.
How is this calculator different from a flat-rate solar calculator?
Most solar calculators apply one national-average electricity rate to every user. This one prices the units your system offsets against your own DISCOM's actual telescopic slab tariff — the same rate structure your real bill uses — so the savings reflect your true marginal rate, not an approximation.
What is the eligibility criteria for the PM Surya Ghar subsidy?
You need to own the roof (or have the owner's consent), hold a valid residential electricity connection, not have previously availed a rooftop solar subsidy on that connection, and install Made-in-India (DCR) panels through an MNRE-empanelled vendor. See our PM Surya Ghar subsidy calculator for the full eligibility and amount breakdown.
Can I run my AC on solar power?
Yes — AC is usually the largest single load in an Indian home, and it runs mostly during daylight hours when solar generates the most, making it one of the best matches for rooftop solar. Size your system with your AC's actual usage in mind; see our AC running cost and panel size calculators.
Is solar worth it if my roof gets partial shade?
Partial shading meaningfully reduces output — even shading on one panel in a series string can drag down the whole string's generation, depending on the inverter setup. It's usually still worth exploring with an installer, who can recommend panel layout, micro-inverters or power optimizers to minimize the shading penalty, but expect lower generation than an unshaded roof of the same size.
How does electricity tariff escalation affect my solar payback period?
The payback period itself is based on today's tariff, but your total savings over the system's life grow faster if tariffs rise over time, since solar keeps offsetting units at whatever the current rate is while your net cost stays fixed. See the 25-year cost comparison below for how different tariff-growth scenarios affect cumulative savings.