Ask an installer for a payback period, and you will often get a single confident number. But payback depends on how much of your own power you actually use, not just how much you generate.

So this guide walks through the real formula, then applies it to two worked examples under today’s net billing rules.

Figures below are illustrative, built from typical Pakistan pricing and tariffs as of August 2026. Your own payback depends on your actual bill, usage pattern, and installer quote.

The formula, in plain terms

Payback period is simply system cost divided by annual savings. But the harder part is working out annual savings accurately, since not every unit is worth the same amount.

Units you use yourself save you the full retail rate, currently Rs 37 to 55 per unit depending on your slab. But units you export earn the much lower net billing rate, roughly Rs 10 to 11 per unit.

For the full breakdown of that gap, see our net billing guide.

Why self-consumption ratio changes everything

Because export pays so much less than retail, the share of solar power you actually use yourself now drives most of your savings. A system that exports half its output earns far less than one that exports a tenth.

This is why sizing for your daytime load, not your total bill, matters more under net billing than it used to. Two identical systems can post very different payback periods purely because of when their owners use power.

Worked example 1 — a residential home

Take a 5kW hybrid system costing Rs 900,000 installed, generating roughly 675 units a month. The home previously paid around Rs 35,000 a month on its bill, with most usage happening in the evening.

With a battery storing daytime solar for evening use, assume 60 percent of generation is self-consumed and 40 percent exported. At Rs 45 retail and Rs 10.50 export, that is roughly Rs 18,225 self-consumed plus Rs 2,835 exported each month.

That is about Rs 21,000 in monthly savings, or roughly Rs 252,000 a year. Against a Rs 900,000 system cost, payback lands around 3.6 years.

Worked example 2 — a small business

Take a 20kW on-grid system costing Rs 1,950,000 installed, generating roughly 2,550 units a month. This shop runs its heaviest loads during the day, alongside solar generation, rather than in the evening.

Assume 80 percent self-consumption and 20 percent exported, since daytime-heavy businesses use far more of their own solar directly. At the same rates, that is roughly Rs 91,800 self-consumed value plus Rs 5,355 exported value each month.

That comes to about Rs 97,000 in monthly savings, or roughly Rs 1,166,000 a year. Against the Rs 1,950,000 system cost, payback lands around 1.7 years.

Payback is not the same as ROI

Payback tells you when you break even. ROI tells you what the money earns while it sits there, which is the fairer way to compare solar against other uses of the same cash.

So the simplest version is annual return: yearly savings divided by system cost. The home above returns about 28 percent a year, and the business about 60 percent.

Compare that with a bank deposit tracking KIBOR at roughly 12 percent. On those numbers, solar is doing considerably better than leaving the money in the bank.

Over a 25-year panel life the totals get large, but treat long-horizon figures with care. They ignore inflation, so rupees saved in year 20 are not worth what they are today.

What financing does to the number

Borrowing does not remove the benefit, but it does push out the break-even point. So the cash payback figure is not the one to use if you are taking a loan.

Take the same Rs 900,000 home system at roughly 16 percent. Here is how the tenure changes things.

So a seven-year loan roughly doubles the payback period. Our financing guide covers current rates and monthly installments.

What else shortens or lengthens payback

A higher self-consumption ratio always shortens payback, which is why daytime-heavy businesses tend to beat homes on this number. A battery helps homes shift evening usage onto stored solar, though it adds to the upfront cost.

Panel output drops slightly each year, typically 0.5 to 0.8 percent, which barely moves the payback math. But rising retail tariffs work in solar’s favour, since every self-consumed unit becomes worth more as grid prices climb.

Two costs are easy to forget. Inverters usually need replacing after 10 to 15 years, and batteries sooner, so factor at least one replacement into any long-horizon calculation.

And poor maintenance quietly lengthens payback too. Dust on panels, a faulty inverter, or shading all cut output, and dust matters more in Pakistan than in most markets.

Getting your own numbers right

So start with a real quotation rather than an estimate. Payback is only as accurate as the cost you feed into it. Our cost by size guide shows what each size should run to.

Remember the net billing meter and application sit outside most system quotes. Our application guide covers what that adds.

Frequently asked questions

What is a typical solar payback period in Pakistan today?

Residential systems with average self-consumption typically pay back in 3 to 5 years. Commercial systems with daytime-heavy loads often pay back faster, sometimes in under 2 years, since they self-consume a larger share of what they generate.

Is solar still worth it in Pakistan after the switch to net billing?

Yes, for most buyers, though the case has changed. Savings now come mainly from using your own power rather than exporting it. So a system sized to your daytime load still pays back within a few years.

What is a good ROI on solar in Pakistan?

Annual return is the clearest measure: yearly savings divided by system cost. So a well-sized home system returns roughly 25 to 30 percent a year. And a daytime-heavy commercial system does considerably better.

Does net billing make payback period longer?

It can, compared to the old 1:1 net metering system, because exported units now earn far less than retail. The effect is smaller for buyers who size their system around self-consumption rather than export.

How do I calculate my own self-consumption ratio?

Compare when your solar generates, roughly 9am to 5pm, against when you actually use power. A rough estimate is enough to start, though a smart meter or monitoring app gives a more exact figure over time.

Does a battery improve or worsen payback period?

A battery raises the upfront system cost, but it also raises self-consumption by storing daytime solar for evening use. For evening-heavy homes, that trade usually shortens payback rather than lengthening it.

Is commercial solar payback faster than residential?

Often, yes, because commercial loads tend to run during the day, alongside solar generation. That overlap means more self-consumed units at the full retail rate, rather than units sold at the lower export rate.

Does financing change the payback calculation?

Yes, considerably. Take a Rs 900,000 system at roughly 16 percent. So cash payback of 3.6 years stretches to about 4.5 years on a 3-year loan, or 5.9 years on a 7-year loan.

How long do solar panels last compared to the payback period?

Panels typically last 25 years or more, well beyond a payback period of 3 to 5 years. But inverters need replacing sooner, usually after 10 to 15 years, so budget for that.

Does maintenance affect payback period?

Yes. Dusty panels, shading, and inverter faults all reduce output, which directly lengthens payback. Regular cleaning matters more in Pakistan than in most markets.