- A net metering ROI calculator India payback comes mostly from self-consumption, not export.
- Surplus is worth little — paid at a low rate or lapses, so size to annual use.
- The PM Surya Ghar subsidy (up to ₹78,000 at 3 kW, residential) sharply shortens payback.
- The worked example below is illustrative only — plug in the site's real, verified rates.
- Tariffs, subsidy and settlement change yearly — date-stamp and verify every input.
A solar payback is only as honest as its inputs. The fastest way to lose a customer's trust is a proposal that promises a four-year payback and delivers seven, because the math leaned on export income that never arrived. This worksheet builds the number the right way.
This is an EPC-grade net metering ROI calculator approach: the inputs that drive payback, why self-consumption matters more than export, and a worked example. The example is illustrative only. Tariffs, subsidy and settlement rates change every year, so date-stamp your assumptions and verify the rates with the SERC, the National Portal and the DISCOM before you quote.
What does the payback worksheet do?
The worksheet turns a system size and a set of verified rates into a payback period — how many years of savings it takes to recover the net cost. It is the number that closes a sale, so it has to be right.
Simple payback is the net upfront cost divided by the annual saving. The skill is in getting the annual saving right, because that is where most quotes go wrong. The saving is mostly the value of the units the customer uses or offsets at the retail tariff — not a payout for surplus they send to the grid.
What inputs do you need?
You need six inputs for a residential payback, and a few more for C&I. Each one changes over time, so treat them as live figures, not constants.
- System cost — the installed price before subsidy.
- Subsidy — the PM Surya Ghar amount for residential, if eligible (verify on the portal).
- Annual generation — expected units, which depend on location and orientation.
- Retail tariff — the per-unit rate the customer pays the DISCOM (verify the slab).
- Self-consumption share — how much generation is used on site versus exported.
- Surplus settlement rate — what a year-end surplus earns, often low (verify the SERC rule).
For a C&I site, add the recurring grid-support, banking and wheeling charges and any demand charge, because these cut into the annual saving.
Why self-use beats export value
Self-use beats export because a unit you consume on site saves the full retail tariff, while a unit exported and left as year-end surplus earns only a low settlement rate or nothing. The gap between the two is large.
Under net metering, an exported unit that later offsets your own import is still worth a full retail unit — that is the value of carry-forward. The unit only loses value if it survives to settlement as surplus. So the payback math should value generation at the retail tariff up to the customer's annual use, and at the low surplus rate beyond that. The surplus settlement guide explains why the surplus rate is so low.
Worked example — illustrative only
Here is a worked residential example. Every figure is illustrative and rounded — not a quote. Replace each one with the site's verified numbers. The subsidy figure follows the PM Surya Ghar residential scheme (up to ₹78,000 at 3 kW) and must be verified on the National Portal.
Caption: Illustrative residential net metering payback example, rounded for clarity. Source: structure by the SuryaHub team using PM Surya Ghar and SERC frameworks. Every figure is illustrative, not a quote — tariffs, subsidy, generation and settlement change yearly and must be verified for the specific site.
How to read the payback
In the example, the net upfront cost is about ₹1,02,000 and the annual saving is about ₹30,000, giving a simple payback of roughly 3.4 years. After payback, the system keeps saving for the rest of its life, often 20-plus years.
Two honesty notes for the proposal. First, simple payback ignores the time value of money and tariff inflation; a discounted payback is slightly longer but a rising tariff shortens it again. Second, the saving assumes the generation estimate holds. Always present the payback as an estimate based on stated assumptions, with the date and the verified rates attached.
Sizing around export rules
The right size is the one that meets annual consumption, because generation beyond annual use becomes surplus that earns little. Oversizing adds cost without adding much saving.
Look at the customer's yearly units, allow carry-forward to balance seasonal swings, and size to that. A state's capacity limit may cap the size further. The worksheet makes this visible: push the size past annual use and the extra units land at the low surplus rate, so the payback stops improving and starts getting worse.
Charges that change the math
Two sets of charges move the payback: one-time upfront costs and recurring costs. Both belong in an honest worksheet.
The one-time net metering charges — application fee, meter cost and deposit — add to the upfront figure. For C&I, the recurring grid-support and banking charges reduce the annual saving and can stretch the payback by a year or more. The subsidy interaction works the other way, cutting the upfront cost. Put each one in, verified and dated.
Mistakes that inflate ROI
Most over-optimistic paybacks come from a few avoidable errors. Avoid these and the number you quote holds up.
- Valuing all generation at retail — surplus beyond annual use earns the low settlement rate, not retail.
- Ignoring recurring charges — banking and grid-support charges cut C&I savings every month.
- Using a stale tariff or subsidy — both change yearly; an old figure breaks the math.
- Assuming a high surplus payout — APPC or lapse is the norm, not a generous feed-in tariff.
- Skipping fixed charges — the bill is rarely zero, so the saving is the energy charge, not the whole bill.
How SuryaHub helps you quote honest payback
SuryaHub keeps your verified tariff, subsidy and settlement assumptions with your quotation and proposals, so a payback you build for one site uses the same dated, checked rates as the next. When a SERC or the National Portal changes a figure, you update it once and every new proposal reflects it. SuryaHub is pre-revenue; real pilots are Suryantra Energy and RGESPL, and the example here is illustrative — verify every rate before you quote.
Quote payback you can stand behind
See how SuryaHub keeps verified rates in every proposal.
Related guides
Frequently asked questions
How do you calculate net metering ROI?+
Net metering ROI is calculated by dividing the net upfront cost, after any subsidy, by the annual saving. The annual saving is mostly the value of self-consumed and offset units at the retail tariff, plus any small surplus payout. Tariffs, subsidy and settlement rates change yearly, so verify each before relying on the result.
What is a typical solar payback period in India?+
A residential rooftop solar payback in India is often cited around three to five years after the PM Surya Ghar subsidy, though it depends on the tariff, location and system cost. C&I payback varies more because of demand and banking charges. Any figure is illustrative, so verify the inputs for the specific site.
Does exporting surplus improve solar payback?+
Exporting surplus improves payback only a little, because year-end surplus is usually paid at a low rate or lapses. Most of the payback comes from self-consumption and offsetting your own import at the retail tariff. The best payback comes from sizing close to annual use, not from maximising export.
How does the PM Surya Ghar subsidy affect payback?+
The PM Surya Ghar subsidy, up to ₹78,000 at 3 kW for residential rooftop, cuts the net upfront cost and shortens the payback sharply. It applies to residential systems within the eligible size. The exact amount and eligibility are set by the scheme, so verify the current subsidy on the National Portal before quoting.
What inputs do I need for a net metering payback?+
For a net metering payback you need the system cost, any applicable subsidy, the expected annual generation, the retail tariff, the share of self-consumption, and the surplus settlement rate. For C&I you also need banking and grid-support charges. Each input changes yearly, so date-stamp your assumptions and verify the rates.
Why can a quoted solar payback be too optimistic?+
A quoted solar payback can be too optimistic when it values all generation at the retail tariff, ignores recurring charges, or assumes a high surplus payout. In reality, surplus earns little, and C&I sites face banking and grid-support charges. Use verified, current rates so the payback you promise is realistic.
Sources & references
The payback method uses the national net metering and subsidy frameworks. The example is illustrative — confirm tariffs, subsidy, generation and settlement rates with the SERC, the National Portal and your DISCOM before you quote.
- Ministry of Power — Rights of Consumers Rules ↗
The national net metering framework.
- PM Surya Ghar National Portal ↗
Residential subsidy figures that feed the payback.
- State Electricity Regulatory Commission (SERC) orders ↗
Tariffs and settlement rates that drive the math.
Written by the SuryaHub team · reviewed against MoP, PM Surya Ghar & SERC sources · updated 19 June 2026.
Method: The worksheet uses the national net metering and subsidy frameworks and is re-checked every 30 days. The worked example is illustrative and rounded, not a quote; all rates change yearly and must be verified. SuryaHub is pre-revenue; only Suryantra Energy and RGESPL are real pilots.
Change log: 19 Jun 2026 — first published.