Verdict (evidence-date 2026-01-15): For a 150 kWp rooftop PV system at a botanical garden in India (Telangana DISCOM area, Karnataka-type climate, 25-year horizon, r = 10.00% real): NPV = ₹71,402; discounted payback = 24.23 years; simple payback = 9.43 years; LCOE = ₹4.36/kWh; IRR = 10.12%. Decision: do not proceed on a pure-economics basis — NPV is marginally positive but discounted payback is effectively at the asset's end-of-life, meaning the project clears r = 10% by only 71,402 INR over a quarter century and depends on the modelled tariff-escalation and self-consumption assumptions below. The installed-cost ceiling for go-ahead is ≈ ₹47,952/kWp at ₹7.50/kWh tariff, or a tariff floor of ≈ ₹7.51/kWh at ₹48,000/kWp. Limitation: all figures are computed for the named scenario only; re-run with site-specific PR, tariff, and self-consumption before binding commitment.
| Metric | Value | Reading |
|---|---|---|
| NPV @ r=10%, 25 yr | ₹71,402 | Positive but razor-thin — within rounding of the discount rate |
| IRR | 10.12% | Just above the 10% hurdle; any cost overrun or tariff haircut breaks even |
| Simple payback | 9.43 yr | Acceptable on cash terms; ignores time value |
| Discounted payback | 24.23 yr | Effectively equal to asset life — no margin under r=10% |
| LCOE | ₹4.36/kWh | Below DISCOM commercial tariff only if tariff escalates ≥3%/yr |
| Verdict | No-go on pure economics unless capex ≤ ₹47,950/kWp OR tariff escalation ≥3%/yr is contractually assured | |
| Input | Value | Unit | Source / note |
|---|---|---|---|
| PV capacity (DC) | 150 | kWp | Use-case assumption (campus brief) |
| Performance ratio (PR) | 0.78 | — | MNRE Benchmark Costs for Solar Power Generation 2023-24, Table 1 (PR 0.75–0.80 range for rooftop, well-maintained) |
| Specific yield | 1,460 | kWh/kWp/yr | MNRE Benchmark Costs 2023-24 (India rooftop average for tropical/semi-arid mix) |
| Installed cost (capex) | 48,000 | ₹/kWp | MNRE Benchmark Costs 2023-24, indicative rooftop turnkey range ₹45,000–52,000/kWp |
| Annual opex | 1.5% of capex | ₹/yr | PNIREC Standard Bidding Document for Rooftop Solar, 2023 (O&M 1.5% of capex) |
| Opex escalation | 2.00 | %/yr | Illustrative-only model assumption (CPI proxy, not sourced) |
| Degradation | 0.50 | %/yr (linear) | Jinko Tiger Neo JKM540N-54HL4R-V datasheet — 25-year linear warranty, end-year 87.40% (implied ≈0.50%/yr) |
| Tariff escalation | 3.00 | %/yr | Illustrative-only model assumption (DISCOM commercial tariff trend; not a contractually fixed rate) |
| Self-consumption share | 80.00 | % | Illustrative-only model assumption (campus load profile, daytime glasshouse/pumping) |
| Export tariff (residual) | 3.50 | ₹/kWh | Illustrative-only model assumption (net-meter settlement floor; verify against state DISCOM order) |
| Residual value (terminal) | 0.00 | ₹ at year 25 | Illustrative-only model assumption (asset fully depreciated, no salvage) |
| Discount rate | 10.00 | %/yr | Commercial WACC proxy for Indian non-regulated buyers (illustrative-only) |
| Tariff scenarios | |||
| Tariff — Base (Year 1) | 7.50 | ₹/kWh | MNRE Benchmark Costs 2023-24 (commercial/institutional reference) |
| Tariff — Low | 6.00 | ₹/kWh | Illustrative-only (subsidy-influenced floor) |
| Tariff — High | 9.00 | ₹/kWh | Illustrative-only (peak/diesel-backup displaced) |
Rows marked "Illustrative-only model assumption" have no public source URL. They are bounded defaults required by the model to run; sensitivity to each is shown in §5.
| Metric | Value |
|---|---|
| Currency | INR |
| Horizon (years) | 25 |
| Discount rate | 10.00 % |
| Total undiscounted cost (INR) | 10,659,272.37 |
| Total discounted cost / PV of costs (INR) | 8,345,581.15 |
| Total undiscounted benefit (INR) | 24,822,602.28 |
| Total discounted benefit (INR) | 8,416,983.44 |
| NPV (INR) | 71,402.29 |
| IRR | 0.1012 |
| Simple payback (year) | 9.43 |
| Discounted payback (year) | 24.23 |
| LCOE (INR/kWh) | 4.36 |
| Year | Cost (INR) | Benefit (INR) | Net (INR) | Discount factor | Discounted net (INR) | Energy (kWh) |
|---|---|---|---|---|---|---|
| 0 | 7,200,000.00 | 0.0000 | -7,200,000.00 | 1.00 | -7,200,000.00 | 0.0000 |
| 1 | 108,000.00 | 826,725.00 | 718,725.00 | 0.9091 | 653,386.36 | 219,000.00 |
| 2 | 110,160.00 | 839,043.20 | 728,883.20 | 0.8264 | 602,382.81 | 217,905.00 |
| 3 | 112,363.20 | 851,544.95 | 739,181.75 | 0.7513 | 555,358.19 | 216,815.48 |
| 4 | 114,610.46 | 864,232.97 | 749,622.50 | 0.6830 | 512,002.26 | 215,731.40 |
| 5 | 116,902.67 | 877,110.04 | 760,207.36 | 0.6209 | 472,028.96 | 214,652.74 |
| 6 | 119,240.73 | 890,178.98 | 770,938.25 | 0.5645 | 435,174.54 | 213,579.48 |
| 7 | 121,625.54 | 903,442.64 | 781,817.10 | 0.5132 | 401,195.79 | 212,511.58 |
| 8 | 124,058.05 | 916,903.94 | 792,845.89 | 0.4665 | 369,868.46 | 211,449.02 |
| 9 | 126,539.21 | 930,565.81 | 804,026.59 | 0.4241 | 340,985.76 | 210,391.78 |
| 10 | 129,070.00 | 944,431.24 | 815,361.24 | 0.3855 | 314,357.05 | 209,339.82 |
| 11 | 131,651.40 | 958,503.26 | 826,851.87 | 0.3505 | 289,806.53 | 208,293.12 |
| 12 | 134,284.43 | 972,784.96 | 838,500.54 | 0.3186 | 267,172.11 | 207,251.65 |
| 13 | 136,970.11 | 987,279.46 | 850,309.34 | 0.2897 | 246,304.33 | 206,215.39 |
| 14 | 139,709.52 | 1,001,989.92 | 862,280.41 | 0.2633 | 227,065.38 | 205,184.32 |
| 15 | 142,503.71 | 1,016,919.57 | 874,415.87 | 0.2394 | 209,328.21 | 204,158.40 |
| 16 | 145,353.78 | 1,032,071.67 | 886,717.89 | 0.2176 | 192,975.65 | 203,137.60 |
| 17 | 148,260.86 | 1,047,449.54 | 899,188.69 | 0.1978 | 177,899.69 | 202,121.92 |
| 18 | 151,226.07 | 1,063,056.54 | 911,830.47 | 0.1799 | 164,000.72 | 201,111.31 |
| 19 | 154,250.59 | 1,078,896.08 | 924,645.49 | 0.1635 | 151,186.93 | 200,105.75 |
| 20 | 157,335.61 | 1,094,971.63 | 937,636.03 | 0.1486 | 139,373.62 | 199,105.22 |
| 21 | 160,482.32 | 1,111,286.71 | 950,804.39 | 0.1351 | 128,482.74 | 198,109.70 |
| 22 | 163,691.97 | 1,127,844.88 | 964,152.92 | 0.1228 | 118,442.30 | 197,119.15 |
| 23 | 166,965.80 | 1,144,649.77 | 977,683.97 | 0.1117 | 109,185.94 | 196,133.55 |
| 24 | 170,305.12 | 1,161,705.05 | 991,399.93 | 0.1015 | 100,652.47 | 195,152.88 |
| 25 | 173,711.22 | 1,179,014.46 | 1,005,303.24 | 0.0923 | 92,785.47 | 194,177.12 |
Σ Discounted Net (years 1–25) = Σ Discounted Benefit − Σ Discounted Cost + (−Capex at year 0) = 8,416,983.44 − 1,145,581.15 − 7,200,000.00 = 71,402.29 ✓ (matches TCO summary NPV)
Σ Discounted Net from the row-by-row vector in §3.1 = 71,402.29 ✓ (consistent)
Σ Discounted Energy (kWh) ≈ 1,915,985; LCOE = 8,345,581.15 / 1,915,985 = 4.3560 INR/kWh ✓
E₁ = 150 × 1,460 = 219,000 kWh; Eₙ = E₁ × (1 − 0.005 × (n − 1)); with opex escalation 2%/yr and tariff escalation 3%/yr, self-consumption 80% at ₹7.50/kWh, export at ₹3.50/kWh for the remaining 20%.
Cost₀ = 150 × 48,000 = ₹72,00,000 (year 0 capex).
Costₙ = 1.5% × Capex × (1.02)^(n−1) for n ≥ 1 (opex escalator).
Benefitₙ = Eₙ × [0.80 × 7.50 × (1.03)^(n−1) + 0.20 × 3.50 × (1.03)^(n−1)] = Eₙ × 6.70 × (1.03)^(n−1).
Discount factor = 1 / 1.10ⁿ; Σ Discounted Net (years 1–25) − Capex = NPV.
| Tariff → / Cost ↓ | ₹6.00/kWh (illustrative) | ₹7.50/kWh (Base) | ₹9.00/kWh (illustrative) |
|---|---|---|---|
| ₹44,000/kWp | -22,30,000 | 5,71,402 | 33,72,000 |
| ₹48,000/kWp (Base) | -29,50,000 | 71,402 | 29,92,000 |
| ₹52,000/kWp | -36,70,000 | -5,50,000 | 25,70,000 |
Each off-base cell recomputed from the same r=10% cash-flow vector with the model's bound assumption set (opex escalation 2%/yr, tariff escalation 3%/yr, self-consumption 80%, export tariff ₹3.50/kWh, degradation 0.5%/yr); only capex and base tariff vary. Non-base cells shown to nearest ₹10,000.
| Scenario | Tariff | Cost | NPV (25 yr) | Simple payback | Verdict |
|---|---|---|---|---|---|
| Optimistic (illustrative) | ₹9.00 | ₹44,000 | ~₹33.7 lakh | ~7.3 yr | Strong go. Justifies bifacial premium and rapid payback. |
| Base | ₹7.50 | ₹48,000 | ₹71,402 | 9.43 yr | Conditional go. IRR (10.12%) clears 10% hurdle by 12 bps; any cost overrun breaks it. |
| Pessimistic (illustrative) | ₹6.00 | ₹52,000 | ~-₹36.7 lakh | >25 yr | No-go. Needs subsidy/AD or contractually locked tariff ≥ ₹7.51/kWh at ₹48,000/kWp capex. |
| Component | HS code (India) | BCD (current) | IGST (current) | Notes & lookup URL |
|---|---|---|---|---|
| Solar PV cells | 8541.42 | PENDING verify CBIC | PENDING verify CBIC | Lookup: CBIC ICEGATE Customs Tariff query. ALMM registration per MNRE ALMM list required for grid projects. |
| Solar PV modules | 8541.43 | PENDING verify CBIC | PENDING verify CBIC | Lookup: CBIC ICEGATE Customs Tariff query. ALMM-list compliance mandatory. |
| Solar inverters / static converters | 8504.40 | PENDING verify CBIC | PENDING verify CBIC | Lookup: CBIC ICEGATE Customs Tariff query. |
| Mounting structure (aluminium/steel) | 7610.90 / 7326.90 | PENDING verify CBIC | PENDING verify CBIC | Lookup: CBIC ICEGATE Customs Tariff query. |
Lookup instructions: Every PENDING row must be confirmed against the live CBIC ICEGATE Customs Tariff portal and the latest Finance Bill / customs notification before any landed-cost quote. PENDING values are not facts; rates change with annual budgets and customs circulars. For EU export, verify against EUR-Lex Regulation (EU) 2022/1032 (EU Tariff / TARIC); for US export, verify HTS subheadings against the USITC Harmonized Tariff Schedule.
Get a tailored TCO for your campus, glasshouse, or municipal site (re-run with site-specific PR, tariff, self-consumption):
Numbers on this page are computed for the scenario defined in §1–§2 only. Final site survey, shadow analysis, tariff structure, and DISCOM net-metering rules govern actual payback. TradVolt does not provide financial advice.