Guides · Faisalabad, Lahore, Punjab
Replacing an Old or Faulty Solar Inverter
Short answer
Repair a solar inverter when the fault is outside it (settings, breakers, grid, wiring) or when a manufacturer's warranty covers the fix. Replace it when it is out of warranty with a serious internal fault, parts are not available, or it no longer suits your needs, for example when you want a battery. The new inverter must match your existing panel strings, your connection phase and any battery, and if you have a net metering or net billing agreement, the change should be cleared with your DISCO first.
This guide covers the repair-or-replace decision, how to match a new inverter to an existing system, and the paperwork side. If your inverter is showing a fault right now, start with solar inverter faults and error codes.
Repair or replace?
Many "dead inverter" calls turn out to be a tripped breaker, a grid problem, a moisture fault after rain or a lost Wi-Fi connection. Rule these out first.
| Situation | Usually |
|---|---|
| Fault is outside the inverter (grid, breaker, wiring, settings) | Fix the cause; keep the inverter |
| Inverter faulty and within manufacturer's warranty | Claim through the manufacturer's process |
| Out of warranty, minor fault, parts available from the brand | Repair can be worthwhile |
| Out of warranty, main board or power stage failed | Compare repair cost against a new inverter |
| Repeated failures, or brand no longer supported | Replace |
| You want battery backup and have an on-grid inverter | Replace with a hybrid, or add AC-coupled storage |
| Your load or panel array has grown beyond the inverter | Replace with a larger unit, or add a second inverter |
Two cautions about repair. First, a board-level repair by an unknown workshop can leave the inverter unsafe, and it ends any remaining warranty. Second, an inverter that has failed once for heat often fails again if it stays in the same hot, airless spot. Our guide to where to install your inverter explains why placement matters.
Replacing an inverter
Panels
Fit the new MPPT voltage window
Battery
Compatible voltage and communication
DISCO
Notify if you have net billing
Matching a new inverter to your existing panels
Panels usually outlast inverters, so most replacements keep the existing array. The new inverter must accept what the panels deliver.
- String voltage. The open-circuit voltage of each string, at the coldest morning temperature, must stay under the new inverter's maximum DC input voltage. The working voltage must sit inside its MPPT window in summer heat too.
- String current. Each MPPT input has a maximum current. Modern large-format panels produce more current than older ones, which matters if you also plan to add panels.
- Number of MPPT inputs. If your roof has strings facing different directions, each should have its own MPPT input.
- DC to AC ratio. The panel array can be somewhat larger than the inverter's AC rating, within the manufacturer's limit. Our guide to the inverter DC/AC ratio explains how far is sensible.
Sometimes the strings have to be re-arranged to suit the new inverter. That is normal and should be in the quotation. Our explainer on solar panels in series vs parallel shows how strings are built.
Matching the phase and the battery
- Phase. A single-phase house needs a single-phase inverter; a three-phase connection can use a three-phase inverter, which balances output across phases. If you are converting your connection, decide the inverter at the same time. See three-phase vs single-phase inverters.
- Battery. If you already have a battery, the new inverter must support its voltage (low-voltage 48 V or high-voltage) and communicate with its BMS. Check both makers' compatibility lists. See the BMS explained. If the battery is also ageing, review it at the same time: when to replace or expand a solar battery.
Upgrading from on-grid to hybrid
Replacing a failed on-grid inverter is a natural moment to move to a hybrid. A hybrid inverter can:
- run without a battery at first, with a battery added later;
- supply backup loads during load-shedding once a battery is fitted;
- store midday surplus for the evening, which matters more under net billing, where exported units earn far less than your tariff.
The alternative is to keep a working on-grid inverter and add storage on the AC side. Both routes are compared in adding batteries or more panels to an existing system, and the three system types in hybrid vs on-grid vs off-grid.
The paperwork: your DISCO agreement
If you have a net metering or net billing agreement, your inverter is part of what the DISCO approved. The NEPRA (Prosumer) Regulations, 2026 require approval before changes to a system's technical parameters, and LESCO registers the inverter make and serial number on solar files. Our AMI smart meter guide explains why the inverter on site must match the file.
- Like-for-like swap (same rating, same type): still tell your DISCO, and keep the old and new serial numbers and invoices.
- Larger inverter or added capacity: this is a change of capacity. Owners on old net metering terms have been told that increasing capacity moves them to net billing.
Read our net metering and net billing guide before deciding on a larger unit.
Choosing the replacement
Solar Works Pakistan supplies inverters from Huawei, Sungrow, Solis, GoodWe, Knox, Luminey, Inverex and Primax. The right one depends on your phase, string layout, battery and monitoring needs, not on brand alone. Our best solar inverter comparison and the brands page explain how they differ. Each inverter is covered by its manufacturer's warranty per product.
When comparing quotations, check that the replacement quote includes:
- the exact inverter model and datasheet;
- any string re-wiring, new DC and AC breakers and surge protection;
- removal of the old unit;
- settings for your battery and grid, and monitoring setup;
- testing and commissioning.
Inverter replacement cost
| Job | Price |
|---|---|
| Like-for-like on-grid inverter replacement | WhatsApp for today's rate |
| On-grid to hybrid inverter (no battery) | WhatsApp for today's rate |
| Hybrid inverter with new battery | WhatsApp for today's rate |
| Three-phase inverter replacement for shops or factories | WhatsApp for today's rate |
Current inverter rates are on our solar inverter price page.
How Solar Works handles inverter replacement
We start by diagnosing the fault, so you do not replace an inverter that only needed a breaker or a setting. If replacement is the right answer, our in-house engineers check your strings, phase and battery, choose a compatible model, and list every item by brand and model in the quotation. Our own teams install, test and commission the new unit and set up monitoring. Our work carries a 1-year service warranty under the applicable project terms, and once a complaint is registered we target sending service personnel within 48 hours to begin diagnosis. That is a target for reaching you, not a fix time.
Related guides
Get today's price or a free site survey
Send us photos of the inverter label, the fault screen and one panel label, plus your connection type and battery details.
- 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
Should I repair or replace my solar inverter?
First confirm the fault is inside the inverter. If it is under manufacturer's warranty, claim it. Out of warranty, repair makes sense for minor faults with genuine parts; a failed main board, repeated failures or an unsupported brand usually point to replacement.
Can I put a new inverter on my old solar panels?
Usually, yes. The string voltage and current must fit the new inverter's input limits in both cold and hot weather, and strings may need re-arranging. An engineer should check this before you buy.
Can I replace my on-grid inverter with a hybrid?
Yes. A hybrid inverter can run your panels now and take a compatible battery later. It needs a battery voltage and communication match, and the change should be cleared with your DISCO if you have an agreement.
Do I need to tell my DISCO if I change my inverter?
If you have a net metering or net billing agreement, yes. The regulations require approval for changes to technical parameters, and a larger inverter counts as a capacity change. Check with your DISCO in writing first.
Will a bigger inverter affect my net metering?
It can. Increasing capacity after 9 February 2026 has been reported to move old net metering users to net billing. Confirm with your DISCO before choosing a larger unit.
Does a new inverter come with a warranty?
Yes. Each inverter carries a manufacturer's warranty per product. Keep the invoice and serial number for any claim.
Sources
- NEPRA (Prosumer) Regulations, 2026, SRO 251(I)/2026 (copy hosted by K-Electric)
- The News, "LESCO leads Discos with 2,053MW net metering capacity" (24 Jun 2026)
- Daily Pakistan, "LESCO tightens solar net metering rules, swaps old meters for smart AMI units" (11 Nov 2025)