Updated: August 2026
Here is the fast answer on solar system size for a home in Pakistan, then the honest one. A 1kW solar array in Pakistan makes roughly 120 units a month averaged across the year, about 4 units a day. So the old rule of thumb was simple: divide your monthly units by 120 and buy that many kilowatts. A 600-unit home needs 5kW, a 300-unit home needs 2.5kW, and so on.
That rule died on 9 February 2026. Since NEPRA moved new solar connections from net metering to net billing, the grid now pays you only about Rs 11 for every unit you export, while you still buy back at Rs 22 to Rs 47 a unit. Sizing your system to wipe out your whole bill on paper now means dumping expensive kilowatts into the grid for pocket change. The 2026 rule is different: size the system to your daytime load, not your total units. For most homes that lands 10-25% below the old full-offset number.
This guide turns your monthly units into a recommended kW, counts the panels and roof each size needs, and works a real 600-unit home to show why the last kilowatt often is not worth buying. We do not sell panels; we help you read electricity bills, so the math here stays neutral, including the cases where solar does not pay yet.
Solar system size by monthly units (the short answer)
Find your average monthly units (the “units consumed” line on your bill), then read across. These are on-grid sizes for an unprotected home on a three-phase connection, priced at mid-2026 market rates.
| Monthly units | ~Units/day | Full-offset size (units ÷ 120) | Net-billing sweet spot (2026) | Panels (550-585W) | Indicative on-grid cost |
|---|---|---|---|---|---|
| 200 | ~7 | ~1.7 kW | 1.5-2 kW (often not worth it yet) | 3-4 | Rs 250,000-370,000 |
| 300 | ~10 | ~2.5 kW | 2-3 kW | 4-6 | Rs 350,000-560,000 |
| 500 | ~17 | ~4.2 kW | 3.5-5 kW | 7-9 | Rs 560,000-900,000 |
| 700 | ~23 | ~5.8 kW | 5-6 kW | 9-11 | Rs 780,000-1,080,000 |
| 1000 | ~33 | ~8.3 kW | 6-8 kW | 11-15 | Rs 950,000-1,350,000 |
Costs are July-August 2026 on-grid quotes, roughly Rs 150,000-180,000 per kW installed and a little cheaper per kW as the system gets bigger; they move with the dollar and import duties. A hybrid system with a lithium battery adds 40-70% on top. Treat these as planning numbers and get two or three local quotes before you commit.
Notice the two size columns pull apart as you go up: nearly identical at 200 units, a full 2kW apart at 1000. That gap is the whole story of solar in 2026, and the rest of this guide explains it.
How much does 1 kW actually generate in Pakistan?
The planning figure most installers use is 120 units per kW per month, or about 4 units per kW per day. Pakistan gets 5 to 7 peak sun hours, which is genuinely good by world standards.
That average hides a big seasonal swing. A well-installed, unshaded kilowatt might push 150-180 units in June and only 90-100 in a hazy, short-day December. Dust on the panels, a slightly wrong tilt, or an hour of afternoon shade from a water tank easily knocks 10-20% off, and a single shaded panel can drag down a whole string. So 120 is a sober annual average, not a summer peak. Keep the panels clean and unshaded between 9am and 4pm, when they do most of their work; if a salesman sizes your system on 150 units per kW, your winter bills will surprise you.
Units to kW: how to read your own bill
Your solar size starts with one number: your average monthly units. Do not use a single hot-month bill, or you will oversize. Pull your last 12 bills, add the “units consumed” figures, and divide by 12. If you do not keep old bills, you can open and download them free on our electricity bill calculator and check pages for every DISCO, then average what you find.
Once you have the average, the naive size is that number divided by 120: a house averaging 480 units lands at 4kW on the old logic. But before you buy 4kW, work out how many of those 480 units you burn during daylight, because that single fact decides whether 4kW is right or 1kW too many.
Why net billing changes how you size
Under the old net metering (2015 to early 2026), the grid was a free battery. Every unit your panels exported at noon cancelled a unit you imported at night, one for one. Oversizing was almost free: fill the roof, bank the summer surplus, draw it down in winter. Divide-by-120 was exactly right.
Net billing broke that trade. Since the NEPRA Prosumer Regulations 2026 took effect on 9 February 2026, imports and exports are priced separately in rupees, settled monthly. You export at the National Average Energy Purchase Price, roughly Rs 11 per unit as of August 2026 (published figures range from about Rs 8 to Rs 13, so confirm the current rate with your DISCO). You still import at your normal slab: Rs 22.44 up to Rs 47.20 base per the SRO 279(I)/2026 tariff (your DISCO publishes the same schedule, for example IESCO’s tariff guide), more once taxes and surcharges load on. Our full explainer on net billing vs net metering walks through the mechanics.
The consequence for sizing is direct. A unit you use as it is generated saves you a full slab rate, Rs 36 to Rs 47 at the higher slabs. A unit you export earns Rs 11. That is a three-to-four-times difference for the same unit of sunshine.
| What happens to a daytime solar unit | What it is worth to you (Aug 2026) |
|---|---|
| You use it right then (self-consumption) | Rs 36-47 saved (an avoided import) |
| You export it to the grid | ~Rs 11 credit |
So the size that makes money is the one whose daytime generation you actually consume on the spot, plus a modest surplus. Panels beyond that just feed the grid at Rs 11, which is why the “sweet spot” column above sits below the full-offset column: the extra kilowatts are export machines, and export barely pays now. For the deeper payback picture, see is solar worth it in Pakistan in 2026.
Worked example: sizing a 600-unit home
Take a common Lahore or Multan household: three-phase connection, unprotected, averaging 600 units a month. It runs a 1.5-ton inverter AC most afternoons, a fridge, fans, and a water pump. On the old rule, 600 ÷ 120 = 5kW, and that is what most installers still quote by reflex. Let us test 5kW against a leaner 4kW.
First, the daytime load. The AC pulls roughly 1.3 units an hour over 5-6 daytime hours; add the fridge, pump and fans, and this home burns about 250 units a month during daylight and 350 at night. A 4kW and a 5kW system both cover those 250 daytime units easily, so both still import 350 units at night. The only difference is how much they export at Rs 11.
Without solar, 600 units all land in the 501-600 slab at Rs 40.22 (unprotected consumers get no previous-slab benefit, so the whole month bills at the landing slab), for an energy charge of Rs 24,132.
| No solar | 4kW on-grid | 5kW on-grid | |
|---|---|---|---|
| Monthly generation | — | ~480 units | ~600 units |
| Daytime self-use | — | 250 units | 250 units |
| Units exported | — | 230 units | 350 units |
| Units imported | 600 | 350 | 350 |
| Import charge | 600 × 40.22 = Rs 24,132 | 350 × 36.46 = Rs 12,761 | 350 × 36.46 = Rs 12,761 |
| Export credit | — | 230 × 11 = Rs 2,530 | 350 × 11 = Rs 3,850 |
| Net energy cost | Rs 24,132 | Rs 10,231 | Rs 8,911 |
Now the payback, using base energy charges (real savings run higher, because taxes and surcharges scale with the bill):
- 4kW at ~Rs 680,000. Saves Rs 13,901 a month, about Rs 166,800 a year. Payback: roughly 4.1 years.
- 5kW at ~Rs 850,000. Saves Rs 15,221 a month, about Rs 182,650 a year. Payback: roughly 4.65 years.
Look at what the extra kilowatt buys. Going from 4kW to 5kW costs about Rs 170,000 more but adds only Rs 1,320 a month, because that last kilowatt does nothing but export 120 units at Rs 11. Its marginal payback is about 10.7 years, more than double the first four. Under old net metering the same upgrade paid back in under three years. Net billing flipped it.
The verdict for this home: 4kW is the smarter buy for pure economics. Go to 5kW only if you are about to grow your daytime load, adding a second AC, an EV charger, or a daytime-charged battery. Sizing is not “bigger is safer” anymore. Bigger is slower.
How many panels, and how much roof?
Home panels in 2026 are mostly 550W to 585W half-cut modules (Jinko, Longi, Canadian Solar, Trina and similar). At 585W, one kilowatt is a little under two panels, so:
| System size | Panels (585W) | Bare panel area | Clear roof to plan for |
|---|---|---|---|
| 2 kW | 3-4 | ~100 sq ft | ~150-200 sq ft |
| 3 kW | 5-6 | ~150 sq ft | ~220-300 sq ft |
| 5 kW | 9 | ~250 sq ft | ~350-500 sq ft |
| 7 kW | 12 | ~340 sq ft | ~500-700 sq ft |
| 10 kW | 17-18 | ~490 sq ft | ~700-1,000 sq ft |
The bare panel footprint is about 50 sq ft per kW, but never size on that. A flat roof needs tilt frames and walking gaps between rows so panels do not shade each other, pushing the real requirement to roughly 80-100 sq ft per kW; a sloped roof with flush mounting gets away with 60-70. Orientation matters as much as area: south-facing, unshaded from mid-morning to mid-afternoon. A big north-facing roof or one under a neighbour’s water tank can cap you below what your bill would suggest, and that is a real reason some homes cannot go full size.
Sizing the inverter
The inverter is rated separately from the panels, and matching them is where installers cut corners. Panels are DC; the inverter converts to AC, and it has its own kilowatt rating. The ratio of panel DC to inverter AC is the DC-to-AC ratio, and 1.1 to 1.25 is the healthy band. In Pakistan’s strong sun, stay near the low end, around 1.1 to 1.15, so the inverter does not clip your midday peak.
In practice that means a 5kW panel array pairs well with a 4.5-5kW inverter. Most homeowners simply match the inverter kW to the panel kW, which is fine and leaves a little headroom. Three rules keep you out of trouble:
- Do not undersize the inverter to save money. A 3kW inverter on a 5kW array throws away power every sunny afternoon, exactly when you generate most.
- Buy for the connection, and the future. Net metering and net billing need a three-phase connection, so you want a three-phase grid-tie or hybrid inverter. If a battery is even a maybe, buy a hybrid inverter now; retrofitting one later means replacing the unit.
- Stay within your sanctioned load. The 2026 rules generally cap your system at your sanctioned load, and the inverter’s continuous rating should sit inside it. Your sanctioned load is printed on your bill; if it is lower than the system you want, file a load-extension request first. The full application flow is in our net metering in Pakistan 2026 guide.
Use only an inverter from your DISCO’s approved list, with anti-islanding protection. A cheap unlisted inverter is the most common reason a net-metering file gets rejected.
Battery or no battery?
For pure bill savings, a plain on-grid system with no battery is the cheapest, fastest-payback choice: solar by day, grid at night. The catch under net billing is that your night imports cost Rs 36-47 while your day exports earned only Rs 11, so you sell low and buy high on everything you could not use live.
A hybrid system with a lithium battery closes that gap. It stores your midday surplus and hands it back in the evening, so instead of exporting a unit for Rs 11 and re-buying one for Rs 40, you keep your own. That also carries you through load-shedding, which a grid-tied-only system cannot do (it shuts off when the grid is down, by design). The cost is real: lithium runs about Rs 40,000-60,000 per kWh in 2026, so a 5kWh pack is roughly Rs 250,000-350,000 and a 10kWh pack Rs 450,000-600,000. That storage rarely pays for itself on arithmetic alone; you buy it for backup and to beat expensive evening peak-hour rates. We compare the two setups in detail in hybrid vs on-grid solar in Pakistan.
A middle path many homes take in 2026: size the panels for daytime self-use, skip the battery for now, and buy a hybrid (battery-ready) inverter so you can add storage later.
When solar is not worth sizing up (or buying at all)
Neutral advice means naming the cases where the numbers do not work:
- Low bills, especially protected consumers. A home averaging 150-250 units, particularly a protected consumer on Rs 10-33 slabs, has a small bill to begin with. A 2kW system might save Rs 3,000-4,000 a month, stretching payback past 8-10 years, with much of the output exported at Rs 11. Cutting the bill with efficiency first often beats solar here.
- You might move within a few years. The net-billing agreement is five years and tied to the connection. If you are renting or selling soon, you may not see the payback.
- A single-phase connection you cannot upgrade. Net metering and net billing require three-phase. No upgrade, no grid-tied solar.
- A shaded or small roof. If mid-day shade or a north-only roof caps you at a size well below your daytime load, the economics weaken.
- Mostly-nighttime consumption with no battery. If your load is a night-shift household or an evening-heavy home and you will not buy storage, you would export cheap by day and import dear by night. Add a battery or reconsider.
Before spending on panels, squeeze the bill the cheap way first: inverter appliances, better insulation, shifting heavy loads to daylight. Every unit you stop using shrinks the system you need to buy, and our guide to reducing your electricity bill covers the steps that pay back fastest. A smaller, well-sized system on an efficient house beats an oversized one on a leaky house.
FAQs
What size solar system do I need for 300 units a month?
On the old rule, 300 ÷ 120 is about 2.5kW, and 2 to 3kW is a sensible range for a 300-unit home in 2026. But check how much of those 300 units you use in daylight. If most of your consumption is evening AC and lights, a 2-2.5kW system that covers your daytime base plus a small surplus is smarter than a 3kW that exports the extra at Rs 11. A 300-unit unprotected home sits at the Rs 33.10 slab, so solar still helps, just do not oversize for export.
How many solar panels do I need for a 5kW system?
Nine panels of 585W, or ten of 550W, gives you about 5kW. Budget roughly 350-500 sq ft of clear, south-facing, unshaded roof once you allow for tilt frames and access gaps between rows.
Is 1 kW really 120 units a month in Pakistan?
That is the safe annual average: about 4 units per kW per day. Summer months can hit 150-180 units per kW and winter can drop to 90-100, so 120 smooths the year. Dust, shade, and a poor tilt pull it lower, which is why sizing on 120 (not on a summer peak) keeps you from oversizing.
Should I size my system to cancel my whole bill like before?
Not since net billing began on 9 February 2026. Cancelling your whole bill on paper means exporting a lot of units at about Rs 11 each while you keep importing at Rs 36-47 at night. Size to your daytime load plus a small surplus instead. For most homes that is 10-25% smaller than the old full-offset size, and it pays back faster.
Does a bigger inverter make my system generate more?
No. Generation comes from the panels; the inverter only converts what the panels make. An oversized inverter wastes money, and an undersized one clips your midday peak. Aim for a DC-to-AC ratio near 1.1-1.15 in Pakistan’s sun, and make sure the inverter is three-phase and on your DISCO’s approved list.
Do I need a battery with my solar system in 2026?
Not for grid-tied bill savings. A plain on-grid system is cheaper and pays back faster. A lithium battery (about Rs 40,000-60,000 per kWh) is worth it if you want backup during load-shedding or you want to store cheap daytime units for expensive evening use rather than exporting them at Rs 11. A common compromise is a battery-ready hybrid inverter now, with the battery added later.
How do I find my average monthly units to size a system?
Take your last 12 bills, add the “units consumed” figure on each, and divide by 12. Do not size on one summer bill or you will buy too big. If you do not have the old bills, open and download them free on our bill check and calculator pages for your DISCO, then average them.
What is the cheapest home solar size that still makes sense?
Around 2-3kW, for a home using 300-450 units a month with a decent daytime load. Below that, on very small bills, the payback usually stretches past 8 years and efficiency upgrades give you more per rupee. Above your daytime load, extra kilowatts only earn the Rs 11 export rate, so there is a natural ceiling on how much you should buy.