Solar ROI Calculator: How Long Will It Really Take to Recover Your Investment in India?

Two Numbers Every Solar Buyer Needs to Understand

Payback Period

The time for cumulative savings to equal your net investment.

Return on Investment (ROI)

The efficiency of your investment expressed as a percentage.

India average ROI on residential solar: 18–25% annually. Fixed deposits in India: 6–7% annually. Solar at 18–25% ROI with near-zero risk is one of the strongest risk-adjusted returns available to an Indian homeowner.

The Complete Solar ROI Formula for India

Step 1: Calculate Your Net System Cost

PM Surya Ghar central subsidy: ₹30,000 for 1 kW; ₹60,000 for 2 kW; ₹78,000 (maximum) for 3 kW or larger systems.

Step 2: Calculate Annual Electricity Savings

Rule of thumb: 1 kW solar generates approximately 4–5 units per day, or 1,400–1,600 units per year. Bangalore (BESCOM) tariff 2026: ₹5.75–₹7.20/unit. Hyderabad (TSSPDCL): ₹3.65–₹9.50/unit.

Step 3: Calculate Payback Period

Step 4: Calculate 25-Year Total Return

The 25-year return is not simply Year 1 savings × 25, because two factors compound over time:

• •Tariff escalation: Grid electricity in India has risen 4–6% per year historically; your savings increase while your solar cost stays fixed
• •Panel degradation: Quality panels lose approximately 0.5–0.8% per year; Year 25 output is 80–88% of Year 1

Worked Examples: ROI and Payback for Common System Sizes

Assumptions: Location: Bangalore (5.0 PSH average); Tariff: ₹7.00/unit; Annual tariff escalation: 5%; Panel degradation: 0.7%/year; Maintenance: ₹6,000/year AMC; PM Surya Ghar subsidy applied at maximum eligible amount.

Example 1: 3 kW System — Monthly Bill ₹2,000–₹4,000

Example 2: 5 kW System — Monthly Bill ₹4,000–₹8,000

Example 3: 8 kW System — Monthly Bill ₹8,000–₹14,000

The Variable That Most Homeowners Underestimate: Tariff Escalation

Rising electricity tariffs make solar returns better every year. At 5% annual tariff escalation, a 5 kW system that saves ₹59,500 in Year 1 generates increasing savings each subsequent year:

By Year 25, the same system that saved ₹59,500 in Year 1 is saving over ₹1.9 lakh annually. This compounding effect is what drives the 25-year cumulative savings figures significantly above simple Year 1 savings × 25.

What Reduces Your ROI: Factors That Lengthen Payback

Oversizing or Undersizing the System

A large surplus may not be fully compensated via net metering. A system too small leaves a large portion of your grid bill untouched. The right size matches annual consumption.

Substandard Panel or Inverter Quality

Higher degradation rates (1.0–1.5% vs 0.5–0.7%/year) mean less generation over 25 years. A failed inverter at year 8 represents an unplanned ₹30,000–₹60,000 replacement cost.

Neglecting Maintenance

Dust accumulation reduces output by 15–25%. Routine maintenance is not optional — it is essential to maximising returns over the system's lifetime.

Poor Roof Orientation or Shading

East/west facing panels instead of south generate 15–20% less annually. Persistent shading reduces generation further. Both issues should be identified and addressed at the site assessment stage.

Financing Cost

A solar loan at 5% interest may extend payback to 8–9 years versus a cash purchase. However, an EMI structured to match the current electricity bill makes the arrangement cost-neutral from month one — you pay the EMI instead of the electricity bill.

How to Do a Quick Payback Estimate for Your Home

The Honest Comparison: Solar vs Other Investment Options

Solar sits at the top on returns with very low risk. Illiquidity is real — you cannot sell solar units like mutual fund units — but it is not meaningful for homeowners who plan to remain in the property.

How Arkahub Approaches the ROI Conversation

No Arkahub installation proceeds without a site-specific financial assessment. Payback period is calculated from actual electricity bills, roof orientation data, shade mapping, and current pricing — not national averages. Most Arkahub customers with monthly bills above ₹4,000 achieve payback in 3.5–5 years.