Adding more panels to an existing solar system
Your system's too small now? Here's how adding panels works, when a second system makes sense, and when it's better to start fresh.
Many NSW homes put in a small solar system years ago and now use more power, with bigger households, EVs, air conditioning or plans for a battery. Adding panels is often possible. The right approach depends on your existing inverter, roof space and network rules.
Option 1: add panels to your existing inverter
If your current inverter has spare capacity, extra panels can sometimes be added to it. In practice this is often harder than it sounds:
- Inverter limits. Many older systems were sized with the inverter already close to full.
- Matching panels. Panels on the same string should have matching electrical characteristics. The exact model you have may no longer be made, and mixing different panels on one string can reduce performance.
- Age. Adding new panels to an inverter near the end of its life may mean paying twice.
Option 2: add a second system
A common solution is to install a separate new system with its own inverter alongside the old one. This avoids mismatch problems and lets you use modern panels. Microinverters suit this well, because each panel works independently. A hybrid inverter also lets you add a battery now or later.
Option 3: replace and upgrade
If your existing system is old, underperforming or has a failing inverter, it can make more sense to replace it with a new, larger system. We'll give you an honest comparison.
Want advice for your home?
Our own electricians will look at your setup and give you a straight answer. No pressure, no subcontractors.
Network limits
Your electricity network limits the total inverter capacity and export at your property, and these limits depend on whether you have single or three-phase power. Adding a system counts towards those limits, so we check and apply for network approval before any work.
Incentives on extra panels
Federal STCs can generally be claimed on newly installed additional capacity, but not again on panels that already received them. The number of STCs depends on the size of the new capacity, your location and the installation year, and the scheme steps down each year, with the next reduction on 1 January 2027. We apply eligible STCs as a discount on your quote.
Thinking about a battery too?
If a battery is on your list, plan both together. Extra panels can give a battery more to charge from, especially in winter. Read about adding a battery to existing solar and what size system you need.
Our in-house team has upgraded and extended systems across Sydney and regional NSW for more than 20 years. See our solar page or ask for a free quote.
Frequently asked questions
Can I mix new and old panels?
Not usually on the same string, because mismatched panels can drag down performance. A separate system or microinverters avoid the problem.
Will adding panels affect my warranty?
It can, if someone else works on your existing equipment. Check the terms and use a licensed, accredited installer.
Do I get STCs on the extra panels?
Generally yes, on the new additional capacity, if eligibility requirements are met. Panels that already received STCs can't claim them again.
Is my old inverter big enough?
We'll check its rating, age and condition on site. In many older systems it's already close to capacity.
Sources
- Calculate small-scale technology certificate entitlements (Clean Energy Regulator)
- Small-scale Renewable Energy Scheme (Clean Energy Regulator)
- Solar for households (energy.gov.au)
Government programs and incentives change. Always check the official pages for the latest details.