The most common question we hear from prospective solar customers is: "The numbers sound great, but what will I actually save?" It is a fair question. Vendor claims can be optimistic. This article does the honest maths — using real tariff data, real solar generation figures for Rajasthan and North India, and realistic assumptions about consumption patterns.
First: What Does a Typical Indian Household Spend on Electricity?
Before calculating savings, you need a baseline. Here is what different household profiles typically pay on their electricity bill each month:
| Household Type | Monthly Units (kWh) | Monthly Bill (Approx.) | Annual Spend |
|---|---|---|---|
| Small apartment (1–2 BHK, basic appliances) | 150–250 | ₹1,200–₹2,000 | ₹14,000–₹24,000 |
| Medium home (2–3 BHK, 1 AC) | 300–500 | ₹2,400–₹4,500 | ₹29,000–₹54,000 |
| Large home (4 BHK+, 2–3 ACs) | 600–1000 | ₹5,500–₹10,000 | ₹66,000–₹1,20,000 |
| Small business/shop | 800–2000 | ₹8,000–₹22,000 | ₹96,000–₹2,64,000 |
Tariffs vary significantly by state and slab. In Rajasthan (JVVNL), residential tariffs in 2025 are approximately ₹3.50/unit for the first 100 units, ₹5.50/unit for 101–300 units, and ₹7.00/unit beyond 300 units. Higher slabs mean higher savings — solar has a "tiered savings multiplier" effect.
How Solar Generation Is Calculated
Solar output depends on your location's Peak Sun Hours (PSH) — the equivalent number of hours per day when the sun shines at full 1,000 W/m² intensity. Jaipur and most of Rajasthan average 5.5–6.0 PSH annually, one of the best in India.
Simple Generation Formula
Monthly Generation (kWh) = System Size (kW) × Peak Sun Hours × 30 days × System Efficiency (0.80)
For a 5 kW system in Jaipur: 5 × 5.5 × 30 × 0.80 = 660 kWh/month
The 0.80 factor accounts for inverter losses, wiring losses, dust, temperature derating, and occasional cloud cover. In practice, well-maintained systems in Jaipur routinely achieve 550–700 kWh/month for a 5 kW system.
Real Examples: Three System Sizes
3 kW System — Ideal for a 2–3 BHK Home Consuming ~300 Units/Month
Installation cost after PM Surya Ghar subsidy (₹78,000): approximately ₹82,000–₹1,00,000. At ₹1,600/month savings, the system pays back in roughly 5–5.5 years. Remaining 19–20 years of the 25-year warranty period = pure profit.
5 kW System — Ideal for a 3–4 BHK Home with 1–2 ACs, ~500 Units/Month
Installation cost after subsidy: approximately ₹1,72,000–₹2,00,000. At ₹3,100/month average savings, payback in roughly 55–65 months. A 5 kW system is the sweet spot for most Indian middle-class families — covers the bulk of consumption including summer AC usage.
10 kW System — Ideal for Large Villas, Farms, or Small Businesses
Installation cost: approximately ₹3,72,000–₹4,50,000 (fixed PM Surya Ghar subsidy of ₹78,000 applies). Commercial consumers on higher tariff slabs see payback in as little as 3–4 years. Net metering credits often fully eliminate the electricity bill.
The Payback Period Calculation — Demystified
Payback period is the time it takes for cumulative savings to equal the upfront installation cost. The calculation is straightforward:
Payback Period = Net Installation Cost ÷ Annual Savings
For a 5 kW system: ₹1,86,000 ÷ ₹37,000/year = approximately 5 years. After that, you generate free electricity for the remaining 20 years of the panel's warranted life.
Crucially, this calculation does not account for tariff escalation. Electricity tariffs in India have risen at an average of 5–6% per year over the past decade. As grid tariffs rise, your solar savings increase proportionally — the actual payback period is often 6–12 months shorter than the static calculation suggests.
Net Metering: Getting Paid for Excess Power
When your solar panels generate more than you consume in real time — typically during midday hours when family members are at work or school — the surplus flows to the grid. Your bidirectional net meter records these exports and credits them against your imports.
In Rajasthan, JVVNL credits exported units at the Approved Purchase Price (APP), currently around ₹2.50–₹3.00/unit. While this is lower than the retail import tariff (₹6–₹7/unit for most residential consumers), any credit you accumulate carries forward to the next billing cycle. At the end of the financial year, any remaining credits may be paid out in cash by the DISCOM, though policies vary.
"The real solar savings strategy is simple: maximise self-consumption during the day. Run your washing machine, dishwasher, and water heater between 10 am–4 pm when your panels are producing at peak."
25-Year Savings Projection: Better Than a Fixed Deposit?
Let us compare a 5 kW solar investment (net cost after subsidy: ₹1,86,000) against a bank Fixed Deposit (FD) returning 7% per annum, with solar savings escalating 6% per year alongside tariff increases:
| Year | Solar Annual Savings | Cumulative Solar Return | FD Value (₹1.86L @ 7%) |
|---|---|---|---|
| Year 1 | ₹37,000 | ₹37,000 | ₹1,99,020 |
| Year 5 | ₹46,750 | ₹2,02,450 | ₹2,61,068 |
| Year 10 | ₹62,560 | ₹4,87,000 | ₹3,66,022 |
| Year 15 | ₹83,700 | ₹8,50,000 | ₹5,12,900 |
| Year 25 | ₹1,49,700 | ₹19,30,000 | ₹10,10,600 |
Over 25 years, the 5 kW solar system generates an estimated ₹19.3 lakh in cumulative savings against an initial investment of ₹1.86 lakh — an effective return far exceeding a standard FD. The key difference: solar savings are tax-free household savings, not taxable interest income.
Hidden Savings: What Most Calculators Miss
- Generator fuel savings: Many Indian homes run diesel generators during power cuts. A hybrid solar system with battery backup can eliminate or drastically reduce generator usage.
- Property value premium: Homes with solar systems command a 3–5% higher sale price. On a ₹50 lakh home, that is ₹1.5–₹2.5 lakh additional value.
- MSME depreciation benefit: Businesses can claim 40% accelerated depreciation on solar assets in the first year under Section 32 of the Income Tax Act.
- Demand charge reduction: Commercial connections often pay a fixed "demand charge" based on peak load. Solar reduces peak load during business hours, potentially shifting you to a lower tariff category.
What Reduces Your Savings? Honest Caveats
A credible savings estimate must acknowledge the factors that reduce actual returns:
- Panel degradation: Quality panels lose approximately 0.5% output per year. By year 25, your 5 kW system effectively generates like a 4.4 kW system. This is factored into all projections above.
- Dust and soiling: Inconsistent cleaning can reduce output by 10–20% during Rajasthan's dry months. Budget 2 hours/month for cleaning, or ₹500–₹1,000/month for a cleaning service.
- Inverter replacement: Budget ₹25,000–₹40,000 for an inverter replacement around year 12–15.
- Net metering policy changes: State policies can change. Most states have locked in net metering for existing installations, but new installations may face different terms in future policy revisions.
Even with these caveats, the economics of rooftop solar in India remain compelling. A well-installed system with quality components consistently delivers payback in 4–6 years and returns 5–10x the investment over its warranted lifetime.
