Sunsynk 3.6 ECCO – The Ultimate Home Solar Inverter for DIY

Key Specifications

I bought this inverter in May 2023 for my first home solar installation, and it has earned its place on my wall. I explain why I think it is the best DIY-friendly inverter around, including a deep-dive into squeezing more solar through it.

Why I Think the Sunsynk 3.6 ECCO is the Best DIY Inverter

It has everything you need from an inverter in a home solar energy system, which applies to various cases and systems. I am using this inverter with two strings of solar panels, a battery, and a grid tie. Additionally, I have connected it to Solar Assistant for remote monitoring and automated configuration .

Advantages of the Sunsynk 3.6 ECCO

The standout quality is that it is extremely resilient and forgiving to DIY-ers like me. The inverter is easy to handle due to its compact size and weight. Hence, it is easy to mount on a wall even by one person. In a close second, I will list my favourite features; these are in no particular order:

• Easy integration with LiFePO4 batteries – I connected my Fogstar 5.12k 48V by following simple instructions from Fogstar on how to install the latest firmware on the battery, and the inverter just picked it up and has been working well since then.
• Flexible battery charging Amps configuration – Using the “Charge Amps” setting, I can decide how many Amps the inverter to use when charging the battery.Credit: USER MANUAL SUNSYNK-3.6K-SG01LP1 / SUNSYNK-3.6K-SG03LP1 / SUNSYNK-5K-SG01LP1 / SUNSYNK-5K-SG03LP1

This has a couple of important advantages: A) I can charge the battery at an optimal rate to increase its longevity B) I can make sure charging from the grid doesn’t introduce a larger peak in AC consumption.

• Easy to navigate menu – generally, the control interface buttons and menus are simple and easy to operate.
  There are screens for various configurations. Some of these customisations are ones that you will likely never need. Ultimately, you will use three of them most of the time.
• Compliant with Energy Networks Association – this is important; you must use a compliant inverter for your District Network Operator (DNO) notification to succeed.
• Flexible configuration for export, charging, discharging – the inverter offers six time slots, configurable with start and end time, charging from grid or generator and minimum battery state of charge percentage. This is particularly valuable when working with flexible tariffs or when optimising for export and import in particular hours.Credit: USER MANUAL SUNSYNK-3.6K-SG01LP1 / SUNSYNK-3.6K-SG03LP1 / SUNSYNK-5K-SG01LP1 / SUNSYNK-5K-SG03LP1
• Easy to work with – connectors, ports and cable management are all easily accessible through the bottom of the inverter, and the front panel opens up a wide enough entry to comfortably connect everything. There are safety switches for DC and AC, too.
• Live monitoring via the app and even more flexible configurations through the web-based plant management – one of the recent features is an integration with a flexible tariff provider that lets you configure your energy import and export based on current prices.
• Generator port input, up to 3960W – this is a hidden gem. I used it to connect an additional inverter and expand my solar with another string. You can connect microinverters to it, too. If you want to diversify, you can connect a wind or hydro turbine to your inverter at that port.
  
  For example, I have two strings – facing east and west. I will add a third string by connecting it to a string inverter , and its output will go to the Sunsynk’s generator port.
• Straightforward integration with Solar Assistant – Solar Assistant is the best monitoring application for remotely configuring your inverter. A particular highlight is the real-time stats from the inverter and batteries. The remote configuration I am referring to is via Solar Assistant’s MQTT integration.
• User Manual: a surprisingly easy-to-read and understandable document. Anything I ever wanted to know about the inverter is documented. My favourite is that they use real-world examples to illustrate the information.
• Price – for the features this inverter offers, it simply is of good value for money. Compare it against other options in the UK inverter directory.

Alongside these features, the Sunsynk 3.6 ECCO offers other capabilities, such as island mode, load port output, and load shedding. I haven’t used them, but I am sure that if I decide to, I will be grateful that I don’t need to buy another inverter. Perhaps the first thing from that list I will use is the load port output.

What I Don’t Like About the Sunsynk 3.6 ECCO

There is not much to put on this list. Nevertheless, there are a few things which I can point out:

• The mobile app does not provide real-time data – the mobile app refreshes the data every 5 minutes. Most of the time, this is not an issue; however, when you modify your settings and want quick feedback, it is frustrating. Fortunately, this problem can be solved by connecting Solar Assistant to your inverter.
• It Reads SOC from different batteries at various times – I have two batteries connected in parallel. One of the batteries is designated as a primary, and the inverter’s communication cable connects to it. When batteries are connected to each other, there is always a difference in the State Of Charge (SOC) in each battery, regardless of how hard the BMS works to keep them balanced. At various times, the Sunsynk 3.6 ECCO inverter seems to be picking up the SOC of the primary battery or the other one at an arbitrary principle. This problem was exacerbated by an older version of my battery’s BMS, which reported large gaps in the SOC of each battery. As a result, the inverter drains one of the batteries below the allocated minimum.
• The CT Clamp is inaccurate at a distance. – Sunsynk recommend keeping the length of the cable leading from the CT Clamp to the inverter to a maximum of 15 meters. With cables tidying, this translates to a relatively short distance, which can constrain your options for suitable space for the inverter. The good news is that this problem can be somewhat managed on a budget by extending the line or fixed properly at an extra cost by installing an additional meter.
• Some of the terms in the menus are not intuitive. In addition, a strong online community of users and experts covers some of the most common difficulties in greater depth.

Conclusion

The Sunsynk 3.6 ECCO has been reliable in my home solar energy system since day one. Every feature has been well thought out. The drawbacks are not related to its core job, and I have managed to work around all of them. There is also a loyal customer base and a lively online community if you get stuck. I would recommend it to anyone building their own system. If you are starting from scratch, see our inverter selection guide for how the ECCO compares to alternatives. For the battery side, the Fogstar 16.1kWh is the natural pairing. And if you are considering a battery-only setup before adding solar, the ECCO handles tariff arbitrage without panels perfectly.

Nikola Nedoklanov

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

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Published: March 8, 2026

Last updated: March 10, 2026