Solar Investment vs Fixed Deposit, Which Wins?

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Every month, millions of Indian households receive an electricity bill and simultaneously see their bank FD statement. The FD earns 7.5%. The electricity bill drains ₹6,000. Somewhere in that gap lives a financial question that most people never frame explicitly: what if the ₹3,00,000 sitting in a fixed deposit went into rooftop solar instead?

This guide does the maths honestly. Solar wins on return. FD wins on liquidity. The decision is not as simple as picking the higher IRR.

Direct answer. At ₹8/unit electricity tariff, a 3 kW solar system with PM Surya Ghar subsidy of ₹78,000 models at an IRR of about 32% (about 17% without the subsidy), against an FD rate of 7.5%. Break-even occurs in about 3 years with the subsidy (about 5.4 years without it) on a system that lasts 25 years. Use the Solar vs FD Financial Crossover framework to decide which is right for your stage of life and liquidity needs.

The comparison is not purely about rate of return. Solar is illiquid, maintenance-dependent, location-specific, and irreversible in the short run. FDs are liquid, zero-maintenance, portable, and breakable in 24 hours. Understanding both sides honestly leads to a better decision than simply chasing the higher number.

The Base Case: ₹3,00,000 Invested: Solar vs FD

Fix the FD at ₹3,00,000, a round number for a meaningful deposit. The solar case for a 3 kW system needs only ₹1,02,000 of own funds after the subsidy, so the like-for-like comparison in the chart and savings figures below puts the same ₹1,02,000 into an FD at 7.5%.

Fixed Deposit Scenario

The FD’s headline 7.5% becomes roughly 5.25% post-tax in the highest bracket. For senior citizens with a 5% FD rate and lower income tax, the effective return is even lower.

Solar Investment Scenario (3 kW System)

Modelling assumptions: every generated unit offsets a unit billed at the stated tariff (net metering or self-consumption), tariff held flat, 0.5% annual degradation, ₹1,500 a year upkeep escalating 3%, and an assumed ₹30,000 inverter replacement in Year 12. The MNRE benchmark is ₹50,000/kW for the first 2 kW and ₹45,000/kW beyond (effective 13 February 2024, pmsuryaghar.gov.in); market prices vary by vendor and city.

Note: The IRR calculation uses net capex of ₹1,02,000 (post-subsidy) against 25 years of annual electricity savings. Even at conservative ₹6/unit savings, the modelled IRR of about 23% is well above FD’s 7.5% headline rate. Running the numbers on your own roof size and tariff is easier with a dedicated solar financial modeling tool rather than a spreadsheet built from scratch.

₹35,040. Estimated annual electricity savings from a 3 kW solar system generating 4,380 kWh per year (3 kW × 5 peak sun hours × 365 × 0.80) at ₹8 per unit, about 4.6 times the ₹7,650 a year that the same ₹1,02,000 would earn in an FD at 7.5%. Source: calculated in this article from the stated inputs.

The Solar vs FD Financial Crossover

The Solar vs FD Financial Crossover

This framework identifies the point at which solar’s cumulative savings overtake FD’s cumulative income, and what assumptions drive the crossover timeline.

1. Crossover year: In the model, solar payback occurs in about Year 3 at ₹8/unit (Year 3–4 across ₹10 to ₹6). From Year 4 or 5 onwards, every rupee of electricity savings is pure return with no offsetting cost. FD income, by contrast, is subject to tax every year and the real return erodes with inflation.
2. Tariff escalation multiplier: Electricity tariffs have generally risen over time, though the pace varies by state and year. In the model, 4% annual escalation lifts the subsidised IRR at ₹8/unit from about 32% to about 36%. FD returns are fixed at the contracted rate and do not benefit from tariff escalation.
3. Tax asymmetry advantage: FD interest is taxable income. Solar savings are not. For a salaried individual in the 30% bracket, the post-tax FD return drops from 7.5% to ~5.25%. Solar savings pass through entirely without tax deduction, widening the effective gap to roughly 12 percentage points without the subsidy (17% against 5.25%) and 27 points with it (32% against 5.25%).
4. Liquidity discount: Solar is illiquid for at least 5 years (until payback). Apply a personal liquidity discount rate based on your emergency fund cushion. If your emergency fund covers 12+ months of expenses, the liquidity discount for solar is minimal.

Apply this framework to your numbers: your electricity tariff, your tax bracket, your liquidity cushion, and your electricity consumption, to calculate whether the crossover happens in Year 3 or Year 7 for your specific household.

What Solar Does Better Than FD

The advantages of solar over FD go beyond raw IRR:

• Inflation protection: electricity tariffs rise; FD rates are locked or reset at lower levels in a low-rate environment. Solar locks in free electricity at tomorrow’s tariff, a trend covered in electricity tariff hikes in 2026.
• Tax-free savings: residential electricity savings are not counted as taxable income. FD interest is fully taxable.
• Property value uplift: a solar-equipped home commands a premium at resale. This is increasingly true in metro markets where buyers are energy-cost-aware.
• Environmental benefit: 3 kW of solar generating 4,380 kWh a year displaces about 3 tonnes of CO₂ at a grid emission factor of 0.71 kgCO₂/kWh (an assumed national figure; check the current CEA database, and note that other sources such as IEA estimate higher), relevant for households that value ESG alignment.
• Subsidy advantage: the PM Surya Ghar ₹78,000 subsidy effectively reduces the capital deployed, boosting IRR on the actual cash deployed.

For a deeper analysis of how these returns compare over the full system life, read the LCOE solar India guide.

What FD Does Better Than Solar

Honest comparison requires equal weight to the FD’s genuine advantages:

• Liquidity: FD can be broken in 24–48 hours with a minor interest penalty. Solar cannot be “unwound” without physical removal and resale at a significant loss.
• Zero maintenance: FD requires no site visits, no panel cleaning, no inverter monitoring. Solar requires at least basic annual maintenance and monitoring.
• Portability: FD follows you if you move. A solar system installed on a rented property does not belong to the tenant.
• Guaranteed return: FD return is contractually guaranteed and insured under DICGC up to ₹5 Lakh per bank. Solar return depends on irradiance, inverter uptime, tariff policy, and DISCOM net metering cooperation.
• No counterparty risk: FD does not depend on a solar vendor’s quality or post-installation service quality.

Scenarios Where FD Wins Over Solar

Solar is not the automatic winner in every scenario. FD is a better choice when:

How PM Surya Ghar Subsidy Changes the Maths

The PM Surya Ghar subsidy restructures the IRR calculation significantly. Without subsidy, the IRR on a ₹1,80,000 gross system at ₹8/unit is approximately 17%. With the ₹78,000 subsidy reducing effective capex to ₹1,02,000, the IRR jumps to about 32%.

For the full PM Surya Ghar subsidy calculation, read the PM Surya Ghar subsidy amount guide.

Common Mistakes When Comparing Solar and FD Returns

• Using gross system cost instead of net capex: always subtract the PM Surya Ghar subsidy before calculating IRR. Many blogs compare solar to FD using the full ₹1.5–2 Lakh cost before the ₹78,000 subsidy lands, making solar look worse than it is.
• Ignoring post-tax FD return: most comparisons use 7.5% FD vs a pre-tax solar figure. The real comparison is 5.25% post-tax FD (30% bracket) vs about 17–32% for solar in the illustrative model (savings untaxed).
• Not accounting for tariff escalation: a static ₹8/unit savings figure understates solar’s long-term return. At 5% annual tariff escalation, Year 10 savings are about 55% higher than Year 1 savings (1.05 raised to the 9th power).
• Assuming FD reinvestment at the same rate: FD rates change with the RBI repo rate. A 10-year FD renewing in 2030 may find rates at 5.5% rather than 7.5%. Solar’s return is locked in at installation.

For a full payback period model, including state-specific irradiance data, read the solar inverter payback period guide. Tariffs are set by each state regulator, so use your own DISCOM’s latest tariff order rather than a national average.

A state by state payback comparison is in solar inverter payback period.

Where Qbits Fits

• Hybrid Inverters: Review current QBH model documents and confirm the exact battery, firmware, PV, backup-output, transfer, communication, warranty and project requirements in writing.
• String Sizing Calculator: get the system design right from the first day to maximise generation and IRR.

Contact Qbits with the site, load, equipment and document details relevant to this guide. Confirm the responsible party, deliverable, commercial scope and response time after submission.