Can I upgrade my solar?

There are many reasons why an older, or even a recent solar system might need an upgrade.
If your solar system fails or you want a larger system, how easy is it to get an upgrade? Well, that depends! Robyn Deed talks to solar installers to get some guidance.

Early adopters of solar (with many Renew magazine readers counted among them, of course) are starting to consider system upgrades. This might be because a panel or inverter has failed, or it might be to increase system size as early systems were usually quite small due to the higher cost per watt back then.

But an older system might not meet current standards, so the question arises: are such upgrades allowed? This article looks at some common upgrade cases and provides guidance on what you can and can’t do. The good news is that, in many cases, changes are possible—though there may be upgrades to other parts of the system required at the same time, which can add significantly to the cost.

Why upgrade?

There are many reasons an older (or even a recent) solar system might need an upgrade. While most grid-connected solar panels should have a long life of 20 to 25 years, panels can fail early. However, this is increasingly rare: an NREL study in 2017 found a median failure rate of 5 out of 10,000 panels annually, based on panel replacement figures, for those installed between 2000 and 2015, and double that for those installed earlier (

The inverter (used to convert the panels’ DC electricity to the AC needed by your house) is warranted for a shorter life, often only five years, although you’d hope a good quality inverter would last at least 10 years. But, given that, it’s likely you’ll need to replace your solar system’s inverter at some point in the life of the system.

Renew (formerly ATA, Renew magazine’s publisher) is now also seeing many queries from people with small 1 to 1.5 kW systems wanting to upgrade to a larger system. Smaller system sizes were common until recently, but lower prices and changes in feed-in tariffs now mean that larger systems can get a good payback; for example, a 5 kW system is now about half the price it was in 2012 (source:; also see Solar sizing: big returns in Renew 140).

In addition, many people, as advocated by Renew, are shifting from gas to efficient electric appliances, or considering an electric vehicle, and want their solar system to cover the corresponding increase in electricity usage. Apart from asking about the technical issues, many people also want to know how an upgrade will affect their older system’s higher feed-in tariff—and whether it’s worth it, if they do lose the higher FiT.

Another case is one you might not even think about as a system upgrade. If you need to repair your roof, just taking the panels off your roof and then reinstating them is governed by state electricity regulator upgrade rules. Similarly, there are rules governing what’s allowed when relocating panels or an inverter on the same property—which might happen due to a renovation, or the tree next door growing and overshadowing your panels—or moving them to a new property.

Why is there an issue with upgrading an old system?

Standards for solar system installations have changed over time, meaning that an older system may have panels, an inverter, earthing, isolators or cabling that don’t meet current standards. Following is a quick summary of some of the recent changes to standards that may affect upgrades.

Standards now require that panel frames are earthed and that systems use a new type of non-polarised isolator. There are also new requirements for housing of cables, including the use of high-density conduit and precluding the use of plastic cable ties.

In 2013, standard IEC 61730-2A came in requiring all panels to comply with a fire rating. Many older panels won’t meet this rating, or at least won’t be tested to this rating due to the expense of testing older panels.

Panels in an older system may also not be on the current list of CEC-accredited panels. If an older system uses non-approved panels, it can continue to be used in its original installation, but may not be able to be moved.

Another change in technology that can affect upgrades is that most inverters had changed from transformer-based to transformerless by 2012. This wasn’t a safety or standards-led upgrade; rather, it was a commercial decision by manufacturers as this type of inverter is generally cheaper and lighter.

In 2015, standard IEC 62109 also came into effect which requires that inverters include an ‘earth fault alarm’ to notify the owner if there is an earth fault (where the system’s DC side becomes connected to earth, for example, if a damaged wire—perhaps chewed by a possum!—touches the frame).

Common cases

The complexity of an upgrade is affected by whether it’s classed as a ‘repair’ or ‘alteration’. Repairs are generally allowed without (much) additional work to bring the rest of the system up to scratch (although the system must meet the standards applicable at the original installation date). Alterations require more work to meet the current standards.

Replacing a failed panel (or two)

Replacing a failed panel is a fairly straightforward case, at least in theory, as it is classed as a ‘repair’ rather than an ‘alteration’.  The replacement panel will need to have at least equivalent electrical characteristics to the old panel for a range of specifications. The exact requirements should be handled by your installer and are listed in AS/NZS 5033:2014 clause 2.1.6.

In practice, replacing a failed panel on an old system can get tricky because it may be difficult to find a panel with the right specifications. Modern panels may be 270 watts or more, compared to 150 to 170 watts for old panels. The new panel may need to have the same number of cells, depending on how the array is configured, and will most likely need to have the same physical dimensions so it will fit in the array.

We spoke to several installers about how they manage this. Some plan ahead for failures, putting aside a few of each of the panel types they work with for future warranty callouts. It may be possible to get ‘warranty stock’ from the manufacturer, but this requires time and patience to manage what can be a bureaucratic process. If a suitable replacement panel can’t be found, an alternative is to remove the panel from the array (if multiple strings are wired to a single input on the inverter, you may need to remove a panel from the other strings as well to keep voltages balanced; this may be classed as an ‘alteration’—check with your local state electricity regulator).

If your panels have microinverters installed then failed panels will have no effect on the rest of the array. If using optimisers, then these will cope with unbalanced strings better than non-optimised panels, but this varies with optimiser brand and model.

Here you can see what are commonly called snail trails, areas of discolouration caused by microcracks and cell fractures. The power output reduction can range from minimal to severe, depending on the number and placement of fractures. Image: Image: Photovoltaik-Institut Berlin.
Replacing a failed inverter

If an inverter fails, your first step should be to see if it can be repaired—contact your solar installer or a solar-qualified electrician for advice. If it needs to be replaced, there are a couple of cases governing the replacement.

If you are replacing an inverter with one of the same ‘topology’ (transformer or transformerless) and same electrical specifications (power output, input voltage/current), in all states except Victoria this is classed as a ‘repair’ and can be done without additional work—although it is recommended to install an external earth fault alarm if that is possible. This also applies if it’s an inverter of the same type but with a higher power rating.

In Victoria, however, it is more complex. The replacement is only classed as a ‘repair’ if the inverter is the same brand/model, or is recommended by the manufacturer as the replacement model. For older inverters, it can be quite tricky to find a new one that meets these requirements, unless the installer, supplier or manufacturer have warranty stock, or the manufacturer is willing to specify a recommended replacement model: one installer noted that some manufacturers don’t want to do this as they don’t want to carry the liability if there is a problem. This could result in a fairly simple warranty replacement turning into an ‘alteration’ in Victoria (although there has been some lobbying to change this from installers).

Where the replacement is classed as an ‘alteration’, additional work is required, including: all PV panels connected to the inverter must be earthed, an external earth fault alarm must be installed, any isolators must be correctly rated and the new inverter will need to comply with the current standard, IEC 62109. As you might expect, these changes can get expensive!

Adding more panels

You may be able to add more panels to your system without upgrading the inverter. Your inverter may have spare capacity (e.g. if you have 2 kW of panels and a 3 kW inverter) or you may decide to oversize your panels relative to the inverter size (e.g. you may opt for 4 kW of panels on a 3 kW inverter).

Oversizing means you lose some generation because the inverter clips any energy production above the inverter rating (in the example above, it would clip production to 3 kW even though the panels could produce up to 4 kW). However, the losses from this are less than you’d think as panels rarely operate at their full power rating (only in the middle of the day, and depending on orientation, shading etc). Note that the CEC currently sets an oversizing limit of 133% to still be able to claim STCs on the panels. The inverter itself may have a limit on oversizing (and may not support it at all).

It may be possible to add new panels to an existing string (panels are installed in one or more strings connected to an inverter input), but they’ll need to be compatible with the existing panels or installed with optimisers on them, and the voltage of the extended string must still sit within the inverter’s specifications. You may also be able to add panels as a new string paralleled with the existing array, but its voltage specs will need to fairly closely match the existing string.

Alternatively, if the inverter has a spare input, the new panels may be added as a new separate array, connected to the unused input. This allows the new array to have different voltage specifications to the existing array.

Both these cases are classed as an ‘alteration/addition’ and there are several requirements. These include: the new panels must have a fire rating; the existing and new panels must be earthed; a correctly rated isolator must be installed; any existing isolator(s) must be checked/rated correctly; and new cables must meet the new standard. Old cables installed to the previous standard do not necessarily need to be upgraded (unless the addition means they are no longer correctly rated), but this is recommended.

In some cases, you may also wish to upgrade the inverter at the same time as adding new panels. This might be because you want a larger inverter, or one with more string inputs, or one with the enhanced functionality available in modern inverters (e.g. diverting excess energy to a hot water system). This will have additional requirements similar to those when replacing a failed inverter.

Another option is to add a completely new system that sits  alongside your existing system. Several installers noted that this is their preferred option as it avoids any issues with the existing system.

Moving your system

If you have older panels that are not fire-rated or not CEC-approved, you are not allowed to move them to another house.

But what about on the same property?

There are rules governing removing and reinstating a system in exactly the same place, as would be required if your roof needs to be repaired. (As an aside, it’s worth considering when your roof is likely to need repair before installing solar panels!)

In all states except Victoria, removing and reinstating the panels is classed as a ‘repair’ rather than an ‘alteration’. The installer needs to tell you about the latest technical and safety requirements and “adopt relevant installation requirements where possible”—thus, you should be able to do this even with panels that aren’t fire-rated or on the current CEC-approved list.

However, in Victoria, removing and reinstating panels is treated as an ‘alteration’ and the installer must reinstall using the latest technical and safety requirements, including requirements on cabling, earthing and isolators. This will also mean that older PV panels that don’t have a fire rating or are not CEC-approved won’t be able to be reinstalled in Victoria (You can see the full Victorian-only rules at

In other states, these more stringent ‘alteration’ rules only apply if you want to move the panels to a different location on the same house. This could happen if you are renovating or if overshadowing from trees means you wish to move the panels to a better location. The CEC document states that if the panels are not fire-rated, the installer must ensure that the risk of fire is minimal, by reviewing such things as roofing material, build-up of combustible materials on the roof and the wiring configuration. Installers may, understandably, be reluctant to take on this risk.

When it comes to inverters, in all states, removing and reinstating an inverter in the same place can be done without additional requirements. However, older inverters that aren’t compliant with IEC 62109 cannot be moved to a new location on the same or a different property—but it is worth checking with state regulators for full requirements.

Why an installer may be reluctant to do an upgrade

The standards may allow an upgrade without significant rework, but an installer may still be reluctant to do it (or may quote to do more work than the standard requires). One issue is that, by modifying the system, they could be held responsible for an issue arising from the original installer’s work. The standard is also vague in certain areas, so they may not be completely sure about the requirements, or they may doubt that the requirements are sufficient. For example, the standard may not require conduit to be added to an old installation, but they may prefer to do this for safety. It is worthwhile asking around to find a trusted installer and/or getting several opinions on what is required.

Will I lose my premium FiT?

One issue for many people with older systems is whether they will lose their high feed-in tariff if they upgrade the size of their system. Some higher feed-in tariffs have already expired, but there are some still in operation, varying by state. If you have a high feed-in tariff, you will lose that higher FiT if you upgrade, but it is worth analysing whether, in the long run, you might be better off with a larger system on the new FiT. As one installer noted, if you have a small system, you may not be exporting very much anyway.

Avoiding waste

What can you do with older working panels you can no longer use? If the panels are compliant with current standards, they can be used on- or off-grid, so you should be able to sell them on eBay or Gumtree—or contact your solar installer who might find them useful for warranty stock.

If the panels aren’t compliant with current standards, they may be able to be used in non-building-mounted systems, for example on RVs or for pumps on farms. The other option is to recycle them. However, there are still limited recycling options in Australia. Your installer may have access to recycling via manufacturer take-back schemes. ReclaimPV has said they are gearing up to work with more manufacturers and also individual householders, so contact them.

Important note

This article is general in nature only and is not intended to substitute for professional advice. Only a CEC-accredited solar installer who has inspected your system can advise you on the exact requirements for your upgrade. However, we hope that this article can point you in the right direction. It is based on CEC’s 2016 document ‘Installation requirements for alterations, additions, repairs and upgrades to existing grid-connected PV arrays’ which provides a user-friendly interpretation of the standards applicable as at December 2016.

When upgrading a system, you also need to consider network requirements, STC eligibility, local laws and feed-in tariffs. Check with your installer for guidance on these.

What the installers say

Jenny Paradiso
Suntrix, SA

Jenny Paradiso from Suntrix, a solar and battery storage company with its head office in SA, says she always recommends that people think of their solar system as a bit like a car: “It will run for years, but will run better and more safely if you get it checked regularly.” This includes cleaning your panels, ensuring there is no debris underneath, the frames are intact and bolts are tight, your cabling is neat and in good condition, and each of your strings is producing the expected output.

Suntrix is seeing more queries from households with older inverters failing (about one a month), some under warranty and some not. It’s a fairly easy, low-cost option to change to a new inverter (in SA) with the price roughly ranging from $400 to $900 for an inverter that is out of warranty, including installation.

Queries about panel replacement are less frequent. “It’s quite rare to find just one faulty panel,” says Jenny, though they have occasionally had to replace panels hit by a golf ball or due to “extreme hail, the sort that was denting car bonnets.” Usually it’s the whole array that needs replacing, which is easier. When replacing a panel, they do any work required to bring the existing system up to the current standards.

Whenever possible, Suntrix keeps panels in stock for warranty calls, as it can be hard to find a similar model later. If needed, they try to source replacements from wholesalers and suppliers, but it can often take months; in one case, the manufacturer made one for them!

To add more panels to a system, adding a second system is “a piece of cake”—and this is what most people end up doing. Before upgrading, they talk to people about whether a larger system will reduce their bills and provide a good payback. Many people with a 1.5 kW system on the premium FiT “aren’t seeing much of the FiT” as they use most of the generation on site. Although, if their current system is working well to reduce their bills, they’ll suggest they “do nothing.”

As an aside, they are installing quite a lot of batteries, but they are clear with people that the payback period is often not much less than the battery’s warranted life. But some people want to “stick it to the man” and some just want to be early adopters. Some people want them for blackouts; for example, companies with fridges for expensive medication, people with disabilities. But you need to be clear how much redundancy is needed—two days of power backup might not be feasible.

Adrian Luke
DMS Energy, Tasmania

Adrian Luke from DMS Energy in Tasmania says they are getting two or three enquiries per week for solar system upgrades or battery storage.

DMS approaches each upgrade on a case-by-case basis. They always start with an on-site visit to examine the panels and the inverter. “You’d be foolish not to run your eye over an old system before adding to it,” says Adrian.

They check and potentially replace the isolator and look for yellowing of panels, microcracks and ‘snail trails’. If many panels have this, they suggest replacing all of them.

If the panels and inverter are in good nick, they recommend incorporating a new system with what you’ve got. This could happen in various ways:

If you have a large enough inverter (e.g. 5 kW on a 2 kW array) with a spare MPPT input, the cheapest option is to add another string; you just need to make sure the second string meets current standards.

If you have a single MPPT input inverter, it may be possible to add more panels to the string, but you’re unlikely to be able to find matching ones, so they’ll suggest one of several things: add another system to sit next to the original or replace the old inverter or add optimisers to all the panels as the panels then don’t need to match in terms of wattage. Or they might recommend both replacing the inverter and adding optimisers.

Adrian is sceptical about the worth of manufacturer panel warranties. To act on a warranty for a panel, they often need to send the panel to China for testing, which takes time and money. Even if they can get a warranty replacement panel, often it’s not compatible with the existing array; instead they use their own warranty stock (they keep a few spares of all the panels they sell) and on-sell the warranty replacement panel.

Adrian says, “Buy quality to try to avoid the problem as far as possible!”

Adrian adds that recycling panels is tricky: “Manufacturers have agreements with PV Cycle but there’s currently little happening in Australia.”

Stephen Ingrouille
Going Solar, Victoria

Stephen Ingrouille from Going Solar in Victoria has seen the difficulties with replacing failed inverters under the current Victorian rules. If you can find a like-for-like replacement, it’s a minimal cost, maybe an additional $300 for the installation costs on top of the inverter cost. “But if you can’t find an equivalent inverter, or the customer wants a different inverter, the costs can quickly escalate,” he says, citing one example where the cost was going to be $7000 because the panels would all have to have been replaced (and it was a very difficult roof).

They rarely see panel failures where quality panels were used in the initial install, maybe one system every couple of years, and these are usually covered under warranty. “We can usually source the stock we need on eBay,” he says. As with the other installers, he stresses the importance of quality to minimise issues.

With inverters, they look at the warranty length as an indication of quality.

Whether an upgrade is worth it depends partly on the older system’s size. Most of the older systems they installed were 3 kW or more, so if the customer is getting the 66 c premium feed-in tariff, they recommend keeping the system for the moment. “But it’s different if it’s a smaller 1 or 1.5 kW system,” says Steve. In that case, they’ll recommend fully replacing and enlarging the system if possible, as chances are that, with a smaller system, the customer is not exporting much anyway.

Thank you to Mick Harris from Envirogroup and Pat Southwell from the CEC for their reviews of this article.