Guides · Faisalabad, Lahore, Punjab
Sizing Your Solar System Under Net Billing: Self-Use First
Short answer
Under net billing, size your solar system to cover the electricity you use during daylight hours, not to export as much as possible. Every unit you use yourself saves your full tariff, while every unit you export is credited at a much lower rate, reported at about Rs 10-11 per unit when the rules were notified. Extra panels still produce value, but each kW added beyond your daytime load is worth noticeably less than the first ones.
For the rules themselves, read our net metering and net billing guide.
What changed, in one paragraph
On 9 February 2026, NEPRA's Prosumer Regulations replaced net metering with net billing for new connections. Units you take from the grid are billed at your normal tariff. Units you export are credited separately at the national average energy purchase price. Your solar capacity cannot exceed your sanctioned load, the agreement runs for five years, and DISCOs cannot accept new connections on a transformer once connected solar reaches 80% of its rating. Under the old system, an exported unit cancelled an imported unit one for one, so oversizing was cheap. Now it is not.
Sizing under net billing
Daytime use
Solar runs your own loads first
Export
Surplus sold at about Rs 10–11 per unit
Import
Night units at the full tariff
The rule of thumb: daytime load first
Think of your solar output in two parts:
| Where the unit goes | What it is worth (illustrative) |
|---|---|
| Used in your home or factory while the sun is up | Your full tariff, for example Rs 50 |
| Exported to the grid | The export rate, for example Rs 10 |
| Stored in a battery and used after sunset | Your full tariff, minus battery losses |
So the first question is not "how many kW fit on my roof?" but "how much power do I use between about 9 AM and 4 PM?"
Step 1: Work out your daytime use
- Collect 12 months of bills. Note the monthly units. Our guide to reading your electricity bill explains each line, including sanctioned load.
- Split day from night. List what runs in daylight: ACs, fans, water pumps, washing, office equipment, machines. Then list what runs after sunset. If you have a time-of-use meter, the peak and off-peak units on your bill help.
- Look at summer and winter separately. Summer daytime use is usually much higher because of ACs. Winter use is lower, and so is solar output.
- Estimate a daily daytime figure. Example arithmetic only: a home using 1,500 units in July (about 50 a day) might use 35 of those in daylight and 15 at night.
Step 2: Match panels to that daytime figure
Use an indicative yield to convert units into kW. In Punjab, a good unshaded system gives very roughly 3.6 to 4.4 units per kW per day averaged over the year, with spring and summer higher and winter lower. See how many units a solar system produces in Punjab.
Example arithmetic only: 35 daytime units ÷ about 4 units per kW ≈ 9 kW. A system of about 9 to 10 kW would cover most of this home's summer daytime use.
Then check the limits:
- Sanctioned load: your solar capacity cannot exceed it. If it is lower than the size you need, increase your sanctioned load first.
- Connection type: the regulations refer to three-phase 400 V or 11 kV consumers. A single-phase home that wants to export usually needs a three-phase connection first.
- Roof space and shading: see the solar system price guide for sizes and costs.
Step 3: Test whether going bigger is worth it
This is where net billing changes the decision. Here is the same home, comparing a 10 kW and a 15 kW system on an average summer day.
Example arithmetic only. Assumptions: about 4 units per kW per day, 35 units of daytime use, tariff Rs 50, export rate Rs 10. These are round numbers, not your tariff or a forecast.
| 10 kW system | 15 kW system | |
|---|---|---|
| Units produced per day | 40 | 60 |
| Used directly (never all of it, because load and sun do not line up hour by hour) | 32 | 34 |
| Exported | 8 | 26 |
| Value of self-used units | 32 × 50 = Rs 1,600 | 34 × 50 = Rs 1,700 |
| Value of exported units | 8 × 10 = Rs 80 | 26 × 10 = Rs 260 |
| Daily value | Rs 1,680 | Rs 1,960 |
| Value per kW per day | Rs 168 | about Rs 131 |
The extra 5 kW adds only about Rs 280 a day, or about Rs 56 per extra kW, against Rs 168 per kW for the first 10 kW. The first 10 kW are more than twice as valuable per kW as the next 5. Whether the extra 5 kW is still worth buying depends on its cost; divide that cost by its yearly value, as shown in our solar payback guide.
Step 4: Decide whether a battery earns its place
A battery turns surplus midday units, worth the export rate, into evening units, worth your full tariff.
Example arithmetic only: in the 15 kW case, suppose a battery stores 10 of the 26 exported units and returns about 8.5 at night after losses. You give up 10 × Rs 10 = Rs 100 of export credit and avoid 8.5 × Rs 50 = Rs 425 of night-time grid units. That is a gain of about Rs 325 a day, before battery wear.
That is why many new systems under net billing are hybrid. A battery also covers load-shedding, which has a value no sum can show. Size it from your night-time loads using the battery sizing guide, and compare options on the lithium battery price page. Set the inverter so it uses the battery in the evening rather than holding it full; our guide to SBU and SUB modes explains the settings.
Step 5: Shift loads into daylight
Running pumps, washing machines and irons between late morning and mid-afternoon, and pre-cooling rooms before sunset, raises your self-use share for free.
Special cases
No net billing agreement yet. If you connect solar to the grid without an agreement, you should not export at all. A zero export device limits the inverter to what you use. In that case, oversizing wastes even more, because surplus is simply throttled.
You already have net metering. Agreements made under the old rules keep their terms until they expire. Adding panels or changing capacity can move you onto net billing, so check with your DISCO before expanding. See adding batteries or panels to an existing system.
Winter and future growth. In winter both your daytime load and solar output fall, so check the match in both seasons. If you plan to add ACs or another floor to the house, leave room in the inverter and structure for later expansion. Our hybrid vs on-grid vs off-grid guide helps you choose the system type.
How Solar Works Pakistan sizes under net billing
Our in-house engineers start from your 12 months of bills and your day and night loads, not from roof area, and we show you the assumptions behind any estimate. Use the solar calculator for a first figure.
Solar Works Pakistan prepares and submits the net billing application and documents to FESCO or LESCO on your behalf.
Get today's price or a free site survey
Send us your last 12 months of electricity bills and tell us what runs during the day. We will size the system around your self-use.
- WhatsApp or call: 0336 666 4321
- Email: info@solarworks.pk
- Head office: Main Boulevard, Sargodha Rd, Block F FDA City, Faisalabad
- Lahore branch: 2nd Floor, Jeff Heights, Gulberg, Lahore
- Hours: 9:00 AM to 6:00 PM, daily
- Service area: all of Punjab. See our Faisalabad and Lahore pages, or contact us.
Site surveys are normally free. Solar Works Pakistan was founded in 2021 and has served 300+ customers, including 50+ industrial clients.
Frequently asked questions
Should I oversize my solar system under net billing?
Usually not by much. Panels beyond your daytime load mostly export, and exported units earn far less than units you use yourself. A modest margin for growth and for winter is reasonable; a system built mainly to export pays back more slowly.
What size solar system do I need under net billing?
Start from the units you use in daylight hours, then divide by an indicative daily yield per kW for your area. Check that the result does not exceed your sanctioned load. A site survey refines the figure.
Can my solar system be bigger than my sanctioned load?
Not under the 2026 net billing regulations. Capacity cannot exceed your sanctioned load. If you need a larger system, apply to your DISCO to raise the sanctioned load first.
Is a battery worth it under net billing?
It can be, if you have midday surplus and evening use. A battery turns units that would earn the low export rate into units that save your full tariff, and it gives backup in load-shedding. Its value depends on its price and how many units it shifts each day.
What happens if I add panels to my old net metering system?
Changing capacity after 9 February 2026 can move you from net metering to net billing. Check with your DISCO before expanding, and compare the extra value against the terms you might lose.
Sources
- NEPRA (Prosumer) Regulations, 2026, SRO 251(I)/2026, 9 February 2026 (copy hosted by K-Electric)
- Dawn, "Nepra pulls the plug on net-metering" (10 Feb 2026)