How to Add More Solar Panels With Microinverters (2026 UK Guide)

I ran out of MPPT inputs on my hybrid inverter and needed more panels. Microinverters solved the problem: each panel gets its own small inverter, converts DC to AC right at the module, and feeds into your AC circuit independently. No string voltage calculations, no inverter replacement, no rewiring your existing system.

Microinverters let you add solar panels to any existing system without replacing your main inverter. Each microinverter (£115-160 per panel for Enphase IQ8 series) handles one panel independently. They connect to your AC circuit, so they bypass your existing DC strings entirely. NREL data shows a failure rate of just 0.055% in the first two years, compared to 0.89% for string inverters.

I built a DIY solar energy system for my home in the late spring of 2023. It was a pleasant experience to see it harvest more and more energy each day. But, as the days grew shorter in autumn and winter, the energy production dropped sharply. I realised I needed more panels.

I am sure others have been in this situation too. Luckily there is a simple solution to this problem: add more panels. Easier said than done, though. In this article I will offer a practical solution with microinverters or string inverters alongside a hybrid inverter, read on.

In This Article:

Why Adding More Panels Can Be Challenging?

The usual challenges are related to several reasons.

• Space for panels – your roof can only fit so many panels safely
• You have maxed your inverter’s capacity to take more PV.
• You don’t have spare MPPTs on the inverter – you have space for panels, but they’ll be facing a different direction, and you want them on a separate string.

These constraints can be particularly frustrating when you wish to add a minor upgrade such as one or two panels. For example, there is a sunny patch on a wall that can help you harvest some much needed energy during the winter. Another example is a shed or a garage roof.

Panel Connection Strategies May Be Some Help

Variations in panel wiring may be some help in limited scenarios. For the full picture on sizing panels beyond your inverter’s rating, read our overpaneling guide. Strategies such as connecting panels in parallel or parallel strings could work well when working around inverter voltage capacities. However, these strategies will not help with the other two constraints we listed above.

Expand With Microinverters

Microinverters can help with all of the constraints listed above. They take DC input from a single panel and convert directly to AC. Instead of delivering the AC to your home, you can plug it into your hybrid inverter. Please note, only some hybrid inverters support AC-coupled external sources such as microinverters or string inverters.

Reliability and Energy Gains

Beyond the wiring flexibility, microinverters have a strong reliability track record. According to NREL testbed data (sourced via Solar-Display), microinverters failed at a rate of just 0.055% in the first two years, compared to 0.89% for string inverters. That is roughly 16 times more reliable over the early life of the system.

Shade performance is another area where microinverters pull ahead. Because each panel operates independently, shading one panel does not drag down the whole string. NREL testbed results show energy gains over a shaded string inverter of +3.7% under light shading, +7.8% under moderate shading, and +12.3% under heavy shading.

Enphase IQ8 Model Comparison

The Enphase IQ8 range is the most widely available microinverter option in the UK in 2026. Enphase backs them with a 25-year warranty, compared to the 10-12 years typical for string inverters. The IQ8 also supports a “grid-forming” mode during outages when paired with an IQ System Controller, meaning your panels can keep running even when the grid is down.

For more detail on how microinverters compare to other panel-level options, see our guide to power optimisers.

Microinverters Alongside a Hybrid Inverter

When your existing strings occupy all of the available MPPTs on your inverter, you can expand with microinverters. Bringing the AC output from microinverters directly to the hybrid inverter offers a key benefit: you can charge your battery from the microinverter. It is important to distinguish between configuring your hybrid inverter to charge from the generator or auxiliary AC input (where your microinverters are connected) versus charging from the grid. Such a configuration can help ensure your battery is only charged from the energy your panels produce.

If you are still deciding on your main inverter, see our guide to choosing a solar inverter and the broader solar inverter overview.

Here’s a video where I explain how I applied the same principle but went for a string inverter

Configure Your Sunsynk Hybrid Inverter to Work With Microinverters

Sunsynk hybrid inverters offer superior settings and customisation for adding AC input.

There is a dedicated menu screen for microinverters. This section also works for string inverters as well. You can access it from the Aux Load section.

There is a great benefit to bringing AC from an auxiliary inverter to the Sunsynk hybrid inverter. This way, you can use the AC from the auxiliary inverter to charge the batteries and supply your home.

I ran across a gotcha when configuring a Sunsynk inverter with AC input. To charge the battery with the full potential of the AC input (ensure your DC wiring is correct first), you need to make sure that the Grid Charge setting in the battery charge menu is set high enough. You need to divide the power of your microinverter by the voltage it produces, i.e. 800W/230V=3.5A. So, you need to set the Grid Charge to 4A to ensure this will work well.

Examples of Hybrid Inverters That Support AC Input From Microinverters

Sunsynk stands out in this category. Their inverters support AC input from microinverters or string inverters, generators, wind turbines and the user manual clearly describes how to configure your inverter for each. You can read my review on the Sunsynk 3.6 ECCO inverter I own and find more details in the user manual.

I looked for more examples of hybrid inverters and their support for AC input from microinverters or string inverters. A quick check on City Plumbing’s website, an established retailer of solar energy components in the UK, shows the following options for hybrid inverters.

Regulations

With the introduction of microinverters, you are essentially adding more generation capacity to your system. If the end result is you exceed 3.68kW per phase, you need to apply for a G99 notification with your Distribution Network Operator (DNO). This requirement is to comply with the Engineering Recommendation G99 for generation installations .

My Experience With Adding An Inverter

I have a Sunsynk 3.6 ECCO. I expanded my solar capacity by adding a Growatt 2kW string inverter. Using the method described in the article so far, I connected the Growatt to the AC input port of the Sunsynk. Consequently, I applied for a G99 DNO notification, and received the go-ahead to connect.

In Hindsight

Instead of a 3.6kW inverter, I should have chosen the larger 5.5kW Sunsynk inverter and applied for G99 from the start. When I built my system in 2023, the two-step process of G99 DNO notification looked like a riskier option. With my non-existent experience at the time, I decided staying within G98 regulations seemed easier. Keeping it easy led me to select the smaller inverter.

I applied for G99 anyway, but with a more complicated design than it would have been had I planned for it upfront.

My Reason For Expansion

Why do I need more panels, you might ask? For the winter days. My panels are split into two strings facing East and West. My west-facing string is covered in uniform shadow from a nearby building for five months of the year. I need more solar, so I am building an east-facing gazebo and mounting panels on its roof.

Conclusion

Using microinverters to add a few panels to a constrained string is a viable strategy – for the ROI on extra capacity, see are solar panels worth it. It is even easier if your hybrid inverter supports AC input from microinverters, too. You need to watch out for exceeding the 3.68kW generation capacity per phase. However, you can solve this problem by applying for a G99 DNO and carry on with the expansion.

Nikola Nedoklanov

UK-based solar DIY enthusiast with 5+ years hands-on experience.

About the author

Published: March 8, 2026

Last updated: March 8, 2026