What to do first: run the project first without subsidy, using your bills, usable roof, written design and current DISCOM export rules. Then add only the support you can verify for your live application on the official portal.
Scope: India. Central scheme rules, state/DISCOM procedures, tariffs and export credit can change; this guide deliberately avoids a static state-subsidy table.
Current official check: Use the PM Surya Ghar portal for the live application record and the MNRE residential-CFA guidelines for the controlling central scheme document. Do not treat a vendor’s quotation as subsidy approval.
The only honest ROI formula
Net project cost ÷ realistic annual net benefit = simple payback estimate
But every term must be built from your own current documents.
Step 1: Get an itemised installed quote
Include:
- modules, inverter, structure, cabling, protection, earthing, and monitoring
- engineering and installation
- meter, application, inspection, or DISCOM-related costs
- roof reinforcement or waterproofing
- taxes
- maintenance package
- warranty scope and labour exclusions
- financing charges
Compare approved vendors and equipment models, not only price per kilowatt.
Step 2: Verify the subsidy before counting it
Use the official portal and application flow. Record:
- consumer and connection eligibility
- approved capacity
- vendor requirements
- documents and bank details
- inspection and commissioning steps
- amount shown by the official calculator or approval
- whether any state support is separate
Treat the subsidy as uncertain until the application is accepted and the required process is completed. Do not let an installer subtract an unverified amount from your decision model.
Step 3: Estimate generation conservatively
Use a site survey that considers:
- location and solar resource
- roof orientation and tilt
- shade through the year
- temperature and system losses
- module degradation
- inverter clipping
- dust, cleaning, and downtime
Ask the installer for the assumptions behind the annual-generation estimate and a range, not one perfect number.
Step 4: Split self-consumption from export
A unit used while the system is generating can avoid a retail-energy charge, subject to tariff design. An exported unit may receive different treatment.
Estimate hourly or daytime usage for:
- cooling
- water heating or pumping
- appliances
- work-from-home loads
- EV charging
Then verify with the DISCOM:
- net-metering or net-billing method
- export credit or settlement rule
- capacity limits
- fixed and demand charges that remain
- carry-forward and expiry rules
- billing cycle and meter process
Step 5: Include financing and replacement risk
Count:
- loan interest and fees
- insurance if purchased
- routine inspection and cleaning
- possible inverter or component replacement outside warranty
- roof work that may require panel removal
- downtime and service travel
A long equipment warranty does not always include labour, transport, or every failure mode.
Run three scenarios
Conservative
Lower generation, delayed subsidy, lower export value, financing cost, and maintenance allowance.
Expected
Installer estimate adjusted for credible site losses and the current utility rules.
Upside
High self-consumption, smooth commissioning, and strong generation.
Make the purchase work under the conservative or expected case, not only the sales case.
Application checklist
- Confirm the electricity account and roof rights.
- Apply through the official portal/process.
- Select an eligible vendor and documented equipment.
- Obtain technical approval where required.
- Approve the final design and safety protections.
- Keep invoices, serial numbers, photos, test results, and warranties.
- Complete inspection, meter, and commissioning steps.
- Track subsidy status only through authorised channels.
- Compare the first bills with the model and investigate large gaps.
Make every payback input traceable
For installed cost, retain the itemised quote showing modules, inverter, structure, protection, cabling, metering, civil work, taxes and excluded work. For generation, use the written design yield and loss assumptions, then compare them with shade and usable-roof evidence. For bill savings, separate energy consumed while the system generates from energy exported; apply the current tariff and DISCOM treatment to each rather than multiplying every unit by one retail rate.
Place financing on its own cash-flow line: down payment, interest, fees and payment dates. Add realistic inverter/service downtime and replacement reserves without pretending to know the exact future price. The result should show annual cash flows and cumulative balance, not only “system price divided by one year’s bill.”
Use approval milestones as decision gates
Before paying a non-recoverable amount, reconcile the proposal with the PM Surya Ghar application record, current MNRE guidelines, vendor identity and local DISCOM process. Treat subsidy as zero until the live case shows eligibility; then model timing separately because an approved amount received later does not fund an earlier installer payment.
Require serials, invoices, commissioning evidence, monitoring ownership and warranty documents at handover. Run expected, conservative and no-subsidy cases. If only the upside case repays the loan comfortably, reduce project cost or size, improve the self-consumption plan, or wait for verifiable inputs instead of converting uncertainty into a guaranteed savings claim.
Official sources used
- PM Surya Ghar Portal — Supports the live consumer application and status record.
- MNRE — PM Surya Ghar residential CFA guidelines — Supports central scheme eligibility and process controls.