Grid · Faisalabad, Lahore, Punjab
Zero Export Device: When You Need One Under Net Billing
Short answer
A zero export device is a sensor, either a CT clamp or a smart energy meter, fitted at your grid connection so the inverter can see how much power is flowing out to the grid and cut its own output before any is exported. You need one when your solar system is connected to the grid but you have no approved net billing agreement, or when your DISCO, transformer or sanctioned load limits how much you may export. With an agreement in place, you can set a partial export limit instead of zero.
This guide explains when export limiting is needed, how it works, what to check on your inverter, and the trade-offs.
What a zero export device does
Without export control, an on-grid or hybrid inverter pushes all the solar power it can make. Whatever your loads do not use flows back through your meter to the grid.
A zero export setup adds a feedback loop:
- A CT (current transformer) clamp or a smart meter sits on the incoming grid cable, between your DISCO meter and your loads.
- It measures the direction and size of power flow many times a second.
- The inverter reads this signal. When power starts to flow out, it reduces its output to match your consumption.
- Your loads still run on solar first. The grid only tops up the shortfall.
The same function goes by several names: export limiting, anti-backflow, anti-reverse power, zero feed-in, or "zero export meter". Many inverter brands build the control into the inverter, so the "device" is often just the sensor plus a setting.
How zero export works
Sensor
CT clamp or smart meter at the main supply
Inverter
Cuts output so nothing flows back to the grid
When you need a zero export device
No net billing agreement
Since 9 February 2026, new solar connections that want to export come under NEPRA's net billing rules and need a signed agreement with the DISCO. If you have solar on a normal connection without that agreement, you should not export. Read our net metering and net billing guide for how the rules work.
Export without approval has two problems. First, you are feeding the grid without a contract. Second, depending on the meter, reverse flow may be logged as an event or even counted against you. AMI smart meters measure flow in both directions and report to the DISCO. See our guide to AMI smart meters and net billing.
Single-phase connections
The 2026 regulations make net billing available to three-phase 400 V and 11 kV consumers. Many single-phase homes therefore cannot export at all unless they upgrade. A self-use system with export limited is the usual answer.
While your application is pending
DISCOs can take weeks or months to process a net billing file. If your system is installed before the meter is fitted, set zero export until the agreement and meter are in place. Our green meter and FESCO/LESCO steps explain the process.
Transformer or capacity limits
DISCOs refuse new applications once connected solar on a transformer reaches 80% of its rating, and solar capacity under net billing cannot exceed your sanctioned load. If your file is refused for these reasons, export limiting lets you still use solar for your own load.
Factories with large daytime loads
Many factories use almost all their solar output during working hours. Zero export protects against surplus on Fridays, holidays or during a shutdown, when the load drops but the sun does not. See our industrial and commercial solar page.
CT clamp vs smart meter
| CT clamp | Smart energy meter | |
|---|---|---|
| What it is | A clip-on sensor around the live cable | A small DIN-rail meter wired at the incoming supply |
| Typical use | Single inverter, often single-phase | Three-phase sites, larger systems, multiple inverters |
| Accuracy | Good when fitted correctly | Usually better, measures all phases and power factor |
| Installation | Simple, but direction and position are critical | Needs wiring into the distribution board |
| Cable run | Limited distance to the inverter | Communication cable (often RS485) can run further |
Which one your inverter uses is set by the manufacturer. Some models have a CT port, others a meter port, and some accept either. Solis, for example, documents CT-based export management for single-phase models with a CT port, and a separate export power manager for systems with several inverters.
Three-phase sites need the sensor to see all three phases. Our guide to three-phase vs single-phase inverters explains why phase balance matters.
Common installation mistakes
- CT facing the wrong way. The arrow must point the way the manufacturer specifies, usually towards the grid. Reversed, the inverter reads export as import and may push even more power out.
- CT on the wrong cable. It must sit on the main incoming cable, before any loads branch off, or the inverter sees only part of the picture.
- Generator not considered. On sites with a generator, export limiting also protects the generator from reverse power. Design the changeover so the sensor sees the right source.
- Setting left at default. Export limit must be switched on and set to zero (or the agreed limit) during commissioning, and checked in the monitoring app afterwards.
On-grid vs hybrid inverters with zero export
On-grid inverter with zero export. The inverter throttles output to match your load. Any solar beyond your load is simply not produced. Nothing is stored. It still switches off in load-shedding, as all on-grid inverters must. See can a solar inverter work without a battery.
Hybrid inverter with zero export. The inverter first serves your load, then charges the battery with surplus, and only then throttles. This wastes less solar, because midday surplus goes into the battery for the evening. That is why a hybrid with a lithium battery often suits homes that cannot export. Compare system types in our hybrid vs on-grid vs off-grid guide.
The trade-off: curtailed solar
Zero export means some solar is thrown away. On a sunny afternoon with little load, panels may run well below their capacity.
For example, if your panels could make 10 kW at 1 PM but your house uses 4 kW and the battery is full, the inverter holds output near 4 kW. The other 6 kW is never generated. These are round illustrative numbers, not a forecast for any site.
Two design points follow:
- Size to your daytime load. Oversizing panels gains little if surplus is curtailed.
- Shift loads to midday. Pumps, washing machines, irons and process loads run from solar that would otherwise be lost.
Under net billing, exported units earn only the export rate, reported at about Rs 10-11 per unit when the rules were notified, so the gap between "export" and "zero export" is smaller than it was under net metering.
Zero export device price in Pakistan
| Item | Typical use | Price |
|---|---|---|
| CT clamp kit (single-phase) | One single-phase inverter | WhatsApp for today's rate |
| Three-phase smart energy meter | Three-phase inverter or hybrid | WhatsApp for today's rate |
| Export power manager / data logger | Several inverters on one site | WhatsApp for today's rate |
| Commissioning and settings | Any system | Included in our installation quote |
The sensor must be the one approved for your inverter model. A cheap mismatched meter may not communicate at all. See our solar inverter price guide and the Huawei and Solis brand pages.
How Solar Works sets up export limiting
Our in-house engineers decide at the design stage whether a site will export, export up to a limit, or run zero export. We fit the sensor approved by the inverter manufacturer, set the limit during commissioning, test it under real load, and show you in the monitoring app how to confirm it is working. Every quotation lists the exact inverter model and the export-control hardware. We install with our own teams, with a 1-year service warranty under the applicable project terms.
Get today's price or a free site survey
Tell us your connection type (single-phase or three-phase), sanctioned load and whether you have a net billing agreement. We will design the system to match.
- 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.
Frequently asked questions
What is a zero export device?
It is a CT clamp or smart meter at your grid connection that tells the inverter how much power is flowing to the grid. The inverter then reduces its output so that nothing, or only an agreed amount, is exported.
Do I need a zero export device if I have net billing?
Usually not for zero export, because the agreement lets you export. You may still use the same hardware to set a partial limit, for example to stay within your approved capacity.
Can I install solar without net billing in Pakistan?
You can install a system for your own use. If it is connected to the grid without a net billing agreement, set it to zero export so it does not feed power back to the DISCO.
Does a hybrid inverter need a separate zero export device?
Most hybrids have export control built in, but they still need a CT or meter to measure grid flow. Which one depends on the model, so check the manufacturer's approved accessory.
Will zero export reduce my savings?
It can reduce how much solar you produce on days with low load, because surplus is curtailed. A battery or moving loads to midday reduces the waste. Under net billing, exported units earn much less than your tariff, so the difference is smaller than it used to be.
Can a zero export system work during load-shedding?
An on-grid inverter switches off in load-shedding regardless of export settings. A hybrid inverter with a battery can keep running your backup loads.
What happens if the CT is installed backwards?
The inverter misreads the direction of flow and may export more instead of less. The CT direction and position must be checked during commissioning.
Sources
- NEPRA (Prosumer) Regulations, 2026, SRO 251(I)/2026 (copy hosted by K-Electric)
- Solis, "Export Power Management and Load Monitoring by CT"