Compare discounted grid-only electricity cost with a solar case including imports, exports, CAPEX and operating cost.
This is a discounted cash-cost comparison. It excludes financing, taxes, component replacement, demand charges, outages and changes to export eligibility. Trust level: engineering estimate; verify site and equipment assumptions before purchase or installation.
| Scenario | Grid-only cost | Solar-case cost | Difference |
|---|---|---|---|
| Conservative | ₹7,99,800.12 | ₹6,04,409.90 | ₹1,95,390.22 solar advantage |
| Expected | ₹7,99,800.12 | ₹4,67,218.87 | ₹3,32,581.24 solar advantage |
| Optimistic | ₹7,99,800.12 | ₹3,30,027.85 | ₹4,69,772.27 solar advantage |
Method: compare discounted grid-only bills with solar upfront cost + remaining grid imports + solar OPEX − export credits
Inputs used: Annual load 7200 kWh; solar 7200 kWh; self-use 80%; term 25 years
Assumptions: Annual electricity demand Solar generation used on site before export Discount rate
Scope and warnings: This is a discounted cash-cost comparison. It excludes financing, taxes, component replacement, demand charges, outages and changes to export eligibility.
National Renewable Energy Laboratory · PVWatts supported locations; use a location-specific model for a site estimate · effective PVWatts version 5 documentation · reviewed 2026-09-12
high confidence · Engineering estimate
Supports the transparent solar energy relationship and system-loss planning reference.
Exclusions: Not a structural, electrical or financing assessment. ToolMitra does not query PVWatts automatically.
The grid-only path discounts annual consumption at an escalating tariff. The solar path adds net upfront cost, values on-site solar against avoided grid purchases, subtracts export credit, adds remaining imports and operating cost, then discounts each year.
For 600 kWh monthly demand and 7,200 annual solar kWh, the self-use share determines how much expensive grid energy is avoided and how much receives the entered export rate. The result compares discounted costs over the same analysis period.
No. This is a cash-cost comparison, not an electrical-islanding design. Ordinary grid-tied solar may shut down during outages unless suitable inverter and storage equipment is installed.
Calculations run on your device. Review your results before exporting or sharing them.
Keep annual demand consistent across both paths. Solar self-use cannot exceed consumption, while remaining generation is valued at the entered export rate. Use current tariff documents and a defensible escalation scenario rather than treating the default as a prediction.
Discounted cost is one decision dimension. Reliability, financing, roof repairs, replacement, demand charges and outage operation can change the practical choice even when one modelled cash path is cheaper.
Published by ToolMitra — methods and editorial approach.