Solar net-billing payback calculator

Net billing changed the question

Under net metering, a unit your panels sent to the grid cancelled a unit you took from it. Export and self-consumption were worth exactly the same, so the only thing that mattered was how much the system generated. Sizing up was close to free, and installers sized up.

Under net billing, which NEPRA moved new connections to with effect from 9 February 2026, there is no swap. What you import is charged at the ordinary slab tariff. What you export is bought at a separate buyback rate, and that rate is a fraction of what you pay.

So the question is no longer how much a system generates. It is how much of what it generates you are at home to use. Two identical systems on two houses can pay back years apart purely because one household is in during the day and the other is not.

Why a bigger system is no longer automatically better

Once the panels cover what you draw in daylight, every extra kilowatt makes units that leave the house at the buyback rate. If you pay 50 a unit and are paid 8 for one, that extra capacity earns about a sixth of what the first part of the system earns.

That is why this page reports the split rather than just the total. If most of what your quoted system makes is being exported, the two things that will shorten your payback are moving usage into daylight hours and buying fewer panels, in that order, and neither of them is what a quote will suggest.

Where the rates came from, and what is unsettled

The buyback figures on this page were checked against Dawn, Business Recorder, The Express Tribune and Profit in September 2026, and every one of them was in motion at the time. NEPRA notified the new regulations, then amended them so that agreements signed before the cutover continue under the repealed rules until they expire, then issued a further draft amendment for consultation. The Prime Minister ordered an appeal and there were objections in the Senate. Reported figures for the protected rate differ between outlets.

None of that is a reason to ship nothing, and none of it is a reason to present a number as settled. So the rates are starting points that fill an editable field, and the figure to trust is the one written in your own agreement.

What the payback figure leaves out

It is a straight line at the rates you entered, and that means a lot is missing:

• panels losing output as they age, usually a fraction of a percent a year
• tariffs moving, which would make the system look better
• inflation, financing costs, maintenance and washing
• replacing an inverter part way through, which most systems need
• the fixed charges, meter rent and taxes that stay on your bill whatever the panels do
• seasonal variation, shading, and the summer days when the grid is down anyway

The 25 year figure is the usual panel performance warranty rather than a prediction, and it is quoted at today’s rates because nobody knows tomorrow’s.

This page is installer-neutral: it names no company, suggests no quote and sells nothing. It is a way to check the arithmetic behind a quote you have been given, and it is not investment advice.