In most cases, you can upgrade or replace your solar inverter without replacing your panels.
Your solar panels generate direct current (DC) electricity. Your inverter converts it into the alternating current (AC) electricity your home can use.
Now, in general, solar panels tend to last longer than inverters. Most panel setups are good for at least 25 years, whereas inverters often need replacing after around 10 to 15 years. As a result, it’s perfectly normal to upgrade your inverter without replacing your solar panels.
With that said, you can’t connect any inverter to any set of panels. Your installer must check that the new inverter suits your panels, existing equipment and electricity network connection.
Why might you upgrade your solar inverter?
You might need a new inverter because your existing one has failed or reached the end of its service life. If your original model is no longer available, you’ll need a compatible alternative.
You might also want to upgrade a working inverter for any of the following reasons:
Adding a solar battery
Accessing better system monitoring
Accommodating more solar panels
Adding panels to another roof section
Increasing the amount of power your system can process at once
The thing is, these projects demand different approaches. For example, replacing a failed string inverter with a compatible model may be straightforward. However, changing to a hybrid inverter, increasing the inverter’s output or converting to microinverters requires more design and installation work.
Before you replace a working inverter
If your current inverter works and your system generates electricity as expected, don’t assume a new model will generate enough extra electricity to justify replacing it early. Compare the predicted benefit with the cost before you decide. At Electrical Innovations, we help you do that.
Will a new inverter work with your existing panels?
Yes, usually. But your installer needs to confirm several points:
Panel voltage
Your panels are connected in strings in most solar systems. The combined voltage of each string must sit within the inverter’s operating range.
Your installer will check the voltage your panels produce during normal operation, the minimum voltage needed to start the inverter and the highest voltage the string could reach. Solar panels produce a higher voltage when their cells are cold, so the voltage can rise on a cold, bright morning. If it exceeds the inverter’s maximum DC input voltage, the inverter may shut down or suffer damage. Your installer must therefore calculate the cold-weather maximum rather than relying only on the voltage measured during normal conditions.
Panel current
The new inverter must also be able to accept the current flowing from your panels. When panels are connected in a series string, the voltage increases but the current stays the same.
However, if two or more strings connect to the same inverter input, their currents combine.
Your installer will compare the panels’ normal operating current and higher short-circuit current with the limit for each inverter input. If the panels can supply more current than the inverter can use, you may lose some generation. If their short-circuit current exceeds the inverter’s safety limit, they can’t connect to that input at all.
Solar string arrangement
Your installer will confirm how many panels are connected in each string and which of the inverter’s maximum power point trackers, or MPPTs, each string will use. An MPPT adjusts how a string operates to draw as much power from it as possible.
Separate MPPTs allow the inverter to track strings independently. This helps when your panels face different directions or receive different amounts of shade. Your panels may work with the new inverter, but your installer may need to change the number of panels in each string or connect the strings to different MPPTs.
Inverter type
A standard string inverter is often the simplest type to replace because you have one central unit fitted away from the panels. It converts electricity from one or more panel strings.
If your system uses power optimisers, the new inverter must work with them. Some optimisers only work with inverters from the same manufacturer or product range, which can restrict your options.
A microinverter system doesn’t have one central inverter. Instead, each panel or small group of panels has an inverter fitted beneath it. If one microinverter fails, your installer may need to replace only that unit. Changing the whole system to a different type may require roof work and changes to the cabling and monitoring equipment.
Panel technology
Most crystalline-silicon panels can work with a range of modern inverters. However, some older thin-film and back-contact panels need a specific earthing arrangement or a type of electrical isolation that many inverters don’t provide.
Your installer will identify your panel model and check its requirements before choosing an inverter. These requirements may narrow your options, but they don’t mean you have to replace your panels.
Will a larger inverter generate more electricity?
Not necessarily. Your inverter can only process the electricity your panels generate. For instance, fitting a 5kW inverter to a 4kWp array won’t turn it into a 5kWp solar system.
A larger inverter may help if your current inverter regularly limits, or clips, the panels’ output. Clipping happens when the panels produce more power than the inverter can process. The inverter caps its output, so you lose the excess. The system can’t convert that potential extra output into electricity you can use or export.
However, your system may only reach that limit for very short periods. As such, a larger inverter could recover very little extra energy over a full year. Your installer should compare the predicted annual generation and savings from each option instead of recommending the largest inverter available.
Increasing the inverter’s power can also affect your Distribution Network Operator, or DNO, connection. We’ll explain that below.
Can you replace your inverter with a hybrid inverter?
You can usually replace a standard string inverter with a hybrid inverter. This may make sense if your current inverter needs replacing and you want to add a compatible DC-coupled battery now or in the future.
The hybrid inverter must work with your panels and chosen battery. However, you don’t need a hybrid inverter to add storage. An AC-coupled battery has its own inverter and can often work alongside your existing solar inverter.
When might you need to replace the panels, too?
You may need to replace some or all of your panels if testing finds damage, insulation faults or a level of deterioration that makes it unsafe or uneconomical to keep your current array.
Replacement may also make sense if:
Your panel technology won’t work with a suitable modern inverter
Obsolete optimisers or other panel-level equipment restrict your options
You want more capacity but don’t have enough roof space to keep lower-output panels
You’re already removing an older array for roof repairs
Even then, you may not need to replace every panel. It may be possible to repair a fault, reconfigure the strings or install a separate new array alongside your current system. Your installer should explain your options and the expected value of each one.
Will you need to update anyone?
Possibly. The requirements depend on whether you’re fitting a similar inverter or changing how much electricity your system can supply. Your installer should check this before work starts:
Your DNO
Your Distribution Network Operator, or DNO, manages the local electricity network. Your installer should check whether the DNO needs to be notified about the replacement and whether it must approve a more powerful inverter or battery inverter before installation. They should handle any notification or application.
Your FIT or SEG provider
Replacing your inverter doesn’t necessarily stop your Feed-in Tariff (FIT) payments. However, you must tell your FIT provider about the change, and your installation must continue to meet the scheme rules. Take a meter reading on the day and keep the new paperwork.
If you increase your system’s capacity or change its metering, confirm how this will affect your payments before your upgrade begins. If you receive Smart Export Guarantee (SEG) payments, check the change with your SEG provider, too.
What happens when you replace a solar inverter?
Here’s what should happen when we replace your solar inverter:
Find the cause – A fault code or a drop in generation doesn’t necessarily mean your inverter has failed. Your installer will test the system to rule out problems with the panels, strings, cables or electricity supply.
Test your existing solar array – Your installer will test each string and inspect the cables, connectors and isolators. These checks confirm whether you can keep your existing panels and any other equipment.
Choose your new inverter – Your installer will use the panel details and test results to find an inverter that suits your system. You can also discuss monitoring, battery plans and warranty cover.
Make any required changes – Your new inverter may require changes to the cables, connectors, isolators or protective equipment. Your installer should explain this work and its cost before starting.
Install and test the inverter – Your installer will fit the inverter, test the system and set up your monitoring. You should receive the warranty details, test records and any paperwork needed for your DNO, FIT or SEG provider. (At Electrical Innovations, we handle the installer and DNO paperwork and explain what you need to send to your FIT or SEG provider.)
Get the right inverter for your solar panels
An inverter fault doesn’t mean you need to remove working panels. In many cases, you can keep your array and change only the equipment that has failed or no longer meets your needs.
If your inverter shows a fault, has stopped generating or no longer supports your plans, our solar team based in Derby can test your system and design a replacement. We’ll explain what you can keep, what needs changing and what benefit you can expect.
If you’re based in Derby, Derbyshire or elsewhere in the East Midlands, contact Electrical Innovations to arrange your assessment.
