Solar Payback & Net Metering Calculator
See how fast rooftop solar pays for itself in Pakistan under NEPRA's 2026 net billing rules, with yearly savings and a 25-year table.
Rules verified Oct 2026 · Source: NEPRA Prosumer Regulations 2026 (notified 9 Feb 2026) · Business Recorder · Dawn · Sun data: EU JRC PVGIS
= Rs 110 per watt
Peak sun hours × 75% performance ratio.
All-in: total bill ÷ units.
Share of solar used at home.
As of Oct 2026: ≈ Rs 10–11 (National Average Energy Purchase Price) for new prosumers. Check NEPRA or your DISCO for the current notified rate.
0 to ignore; often 10–20% of system cost.
Formula (year n): output = 10 kW × 4.44 × 365 × (1 − 0.005)^(n−1); saving = output × 60% × Rs 45×(1+0.05)^(n−1) + output × 40% × Rs 10 − 1% × cost. Payback = year when cumulative savings reach Rs 1,100,000.
Payback in 2.2 yrs. Excellent — that's faster than most Pakistani rooftop systems and far quicker than the 25-year panel life. Each self-used unit is worth Rs 45 to you, but each exported unit only Rs 10 — so 87% of your first-year benefit comes from the solar you use at home. Your solar electricity costs about Rs 3.60 per unit over its life versus Rs 45 from the grid today.
| Buyback | Year-1 saving | Payback | 25-yr net |
|---|---|---|---|
| Your rate: Rs 10 | Rs 491,386 | 2.2 yrs | Rs 19,585,717 |
| Legacy: Rs 26 | Rs 595,104 | 1.8 yrs | Rs 22,028,903 |
| No export credit | Rs 426,562 | 2.5 yrs | Rs 18,058,726 |
| Self-use | 0%/yr | 5%/yr | 10%/yr |
|---|---|---|---|
| 30% | 3.4 yrs | 3.3 yrs | 3.2 yrs |
| 50% | 2.5 yrs | 2.5 yrs | 2.4 yrs |
| 70% | 2.0 yrs | 2.0 yrs | 1.9 yrs |
| 90% | 1.7 yrs | 1.6 yrs | 1.6 yrs |
Estimate only. Real savings depend on your tariff slab (solar may also drop you into a cheaper slab), DISCO billing practice, shading, cleaning, outages and future NEPRA decisions. Savings are not discounted except in the IRR.
- • Valuing every solar unit at the full grid rate — under net billing, exported units earn only ~Rs 10–11.
- • Using the old Rs 26 buyback for a new connection.
- • Ignoring degradation, cleaning and an inverter replacement around year 10–15.
- • Using the base slab rate instead of the all-in rate (with FCA, surcharge and 18% GST).
- →Size for daytime use rather than maximum export — oversizing now pays back slowly.
- →Run pumps, washing, ironing and AC between 10 am and 3 pm to lift self-consumption.
- →Financing the system? Compare the EMI with your monthly saving using our Loan EMI Calculator.
- →Keep your DISCO net billing agreement and meter readings — check exported units every bill.
This tool is for informational purposes only. Always verify results with a qualified professional.
What is the Solar Payback & Net Metering Calculator?
The Solar Payback & Net Metering Calculator estimates how many years a rooftop solar system takes to recover its cost in Pakistan, how much it saves every year, and what it is worth over a 25-year panel life. It is built around the way solar now earns money after NEPRA's Prosumer Regulations 2026: units you use yourself save you the full price of grid electricity, while units you export are credited at a much lower buyback rate.
Until February 2026, Pakistan used net metering: every unit exported cancelled one unit imported, and surplus was bought at about Rs 26 per unit (later the national average purchase price). On 9 February 2026 NEPRA notified the Prosumer Regulations 2026, which replace net metering with net billing. Imports are billed at your normal tariff (roughly Rs 37–55 per unit before taxes depending on slab), exports are credited at the National Average Energy Purchase Price of about Rs 10–11 per unit, new agreements run five years instead of seven, and the system cannot exceed your sanctioned load. Existing prosumers keep their old terms until their seven-year agreements expire.
This calculator models each year separately: generation = system kW × daily yield × 365, reduced by panel degradation each year. Self-used units × your electricity rate (rising by the annual tariff increase) plus exported units × buyback rate gives the gross saving, minus yearly maintenance. Payback is the point where cumulative savings equal the system cost. It also shows the internal rate of return (IRR), the 25-year net gain and the levelised cost of your solar electricity per unit.
Worked example: a 10 kW system in Lahore costs Rs 1,100,000. Lahore's PVGIS sun data (5.92 peak sun hours × 75% performance ratio) gives 4.44 kWh per kW per day, so year-one output is about 16,206 units. If 60% is used at home at Rs 45 per unit and 40% exported at Rs 10, the first-year saving is Rs 437,563 + Rs 64,824 − Rs 11,000 maintenance ≈ Rs 491,387. With a 5% yearly tariff rise and 0.5% panel degradation, the system pays back in about 2.2 years and saves about Rs 2.07 crore over 25 years — a net gain of roughly Rs 1.96 crore after its cost.
Because exports earn only about a quarter of the import price, self-consumption is now the single biggest driver of payback. Running pumps, washing machines, irons and ACs between 10 am and 3 pm, or adding a battery, raises the share of solar you use yourself. The sensitivity table below shows how payback changes with self-consumption and tariff increases, and the comparison card shows the difference between the new Rs 10 buyback and the old Rs 26 rate.
How to Use This Calculator
- 1Enter your system size (kW) and the total installed cost from your quote — or use the Solar System Size Calculator first.
- 2Select your city to fill in the daily yield per kW, or type your own figure from an installer's simulation.
- 3Enter your current all-in cost per unit (total bill ÷ units, or use the Electricity Bill Calculator).
- 4Set the share of solar you use yourself and the buyback rate for exported units (Rs 10 default for new net billing).
- 5Adjust the yearly tariff increase, panel degradation and maintenance if you want a more cautious estimate.
- 6Read the payback, 25-year savings, IRR and sensitivity table; expand the year-by-year table or copy a share link.