Skip to content
Bharat Solar Venture
Log in
Menu

Solar ROI and payback calculator

Enter what the system costs, any subsidy, and either the monthly bill it replaces or the units it supplies at the customer's tariff. The calculator subtracts the subsidy, adds up the yearly savings and shows when they overtake the net cost. A table then shows how that moves if savings or cost change.

Calculator

Loading the calculator. It needs JavaScript to run.

How it is calculated

  1. Net cost = system cost minus subsidy.
  2. Monthly saving = the monthly bill the system replaces, or units per month multiplied by the tariff you enter. Yearly saving in year one = monthly saving multiplied by the months in a year.
  3. Each later year the saving is multiplied by one plus the tariff rise and by one minus the output drop, both as you enter them.
  4. Payback = the years until the running total of savings reaches the net cost, worked out inside the final year. If that does not happen within the window shown on the page, the result says so.

Assumptions

  • Every input is yours: the system cost, the subsidy, the bill or the units and tariff, and any yearly change. This page holds no default cost, tariff or subsidy.
  • The subsidy is optional. If you enter one, it is subtracted from the cost; the customer receives it after paying the full price, so the result is an after-subsidy view.
  • Savings: 12 times the monthly saving in year one. With no yearly output drop or tariff rise entered, every year saves the same amount.
  • The model looks 25 years ahead. A system that has not paid back by then is reported as not within 25 years.
  • The what-if table moves yearly savings by -20%, -10%, +10%, +20% and the net cost by -10%, +10%. These are fixed steps, not forecasts.
  • Left out: loan interest, insurance, maintenance, inverter replacement, net-metering credits and the time value of money. The calculator does not store what you enter.

Error reporting is not set up yet: no contact address has been published. (Set NEXT_PUBLIC_CONTACT_EMAIL.)

How we verify data

What the payback figure means

Payback is the point at which the savings added up so far equal the money the customer actually paid. The subsidy is paid to the customer afterwards, so the page lets you enter it and treats it as reducing the net cost. Leave it blank to see the figure without any subsidy.

What is left out

Unless you type a yearly drop in output or a yearly rise in the tariff, every year saves the same amount. Loan interest, insurance, maintenance, inverter replacement, net-metering credits and the time value of money are all left out, so treat the result as a first conversation, not a financial plan.

Using the what-if table

Real savings depend on usage, weather and the tariff, and real costs move with the final quotation. The table recalculates payback with savings and net cost shifted by fixed steps, so a customer can see how sensitive the answer is before deciding. The steps are not forecasts.

Frequently asked questions

Why does the page not suggest a tariff or a system cost?

Both differ from one customer and one quotation to the next, and a default would quietly decide the answer. Every figure comes from you, so the payback matches the customer in front of you.

Should I enter the subsidy?

Only if you want the figure after subsidy. The customer pays the full price first and receives the subsidy later, so the result is an after-subsidy view. Use the subsidy calculator for an indicative amount and confirm it with the nodal agency.

Is the payback a promise?

No. It is arithmetic on the numbers you typed. Real output, tariffs and costs will differ, which is why the what-if table is there. Show it next to the formula so the customer sees the assumptions.

Use this inside Bharat Solar Venture

Put the size, price and indicative subsidy into one branded quotation for the customer, then send the link. Create an account to try it.

Create your account
Create your account