Using a Tigo CCA+TAP to identify problem panels

cormacl

Some details on a recent Tigo CCA+TAP install to diagnose an under-performing string (I have posted this simialrly on the ISOG group on FB)

I have 2 strings in my setup. One is south-facing with 8x405W panels. No issues with that.

The 2nd string is another 8 panels split 4E, 4W on a rear extension. This one has Tigo TS4 optimisers under each panel and has shading challenges in places with obstacles likes trees and even the house itself.

Nothing untypical here. Many people have installations that rely on optimisers to prevent a chimney or other shading issues from affecting the system performance. The advantage with TS4s is that they can be installed on their own and forgotten about and just do the job.

I was a tad disappointed by the 2nd string performance. It is generating power but nowhere near as well as the front south-facing 8. For example, around the mid-day peak periods, the front 8 might reach 3.4kw and the rear 8 at the same time would peak at 1.5kw. I had been expecting a bit more. Even with scaling the front output to say 6 panels (because 2 are shaded most of the time) and then reducing by another 20% (South -> E/W), I would expect 2kw at that peak time and not 1.5. So there seemed to be a shortfall.

So I got myself a Tigo CCA kit recently and set about a self-install. The kit comes with the CCA unit, a DIN rail PSU and a TAP module for communication with the TS4s. I put the CCA and PSU in suitable wiring box in the attic and just plugged it into a nearby socket I have.

You would normally fit the TAP module under one of the PV panels. But in my case, I just put it under the rear main roof fascia overlooking the single story extension below. It was a perfect location with line of sight of all the optimised panels (that pic of the extension roof is taken from where the TAP is located).

I used standard CAT6 cable which will do the job but is not suitable for external exposure. I worked around that with some self-amalgamating tape on the last 15cm to improve the weather-proofing. This can always be replaced with proper weather-grade RS485 in time.

I had to get one of those cheapy Amazon endoscope cameras that have these long bendy wires and attach to your phone. The objective was to feed the camera under the solar panels to try and locate and photograph the serial numbers of each TS4. You need these serial numbers so you can register them and pair up with the CCA. In my first attempt the cheapy endoscope died after an hour. By then I had only managed to get usable pics of two modules. It's a real slow process of trial and error moving around the camera to get the picture.

I registered those two modules I had and about an 20-30 mins later, started to see data. I then opened a support ticket with Tigo who say can "blind scan" for the other modules. In reality, all they can do is rotate the known module serial numbers and guess the serials of other optimisers from the same production batches. Five days later, they had found nothing. In fairness while this seems mediocre, it works this way to prevent anyone pairing with their neighbours TS4s.

So I returned the dead camera and ordered another cheapy one (diferent brand) and had a repeat session on the extension roof. Thankfully this time I managed to get all serial numbers and eventually started to get stats for everything.

Life Lesson #1:

If getting a system with Tigo optimisers, insist your installer do out a panel layout and peel off the serial tags while fitting the optimised panels, sticking them on the layout.

Keep that layout and serials safe and take a photo of it and keep that safe too.

Same advice for installers.. you never know if you may wish to attach monitoring even if only for a temporary period for troubleshooting. It was one thing for me to be farting about on an accessible single story extension. Its a whole other nightmare to be trying to do that on a two-story roof with a larger grid of panels. You'd have to lift all the panels to get the numbers. So the extra few minutes to do the layout and peel the labels is no effort at all. You could also just take photos of all the modules beforehand but it is still better to know where everything went.

Now onto the results I got. The two pics with all green colours for the panels shows the output per panel. The right-side legend for "Energy" shows the Watt hours per panel for the full day. The other green-coloured image with the "Power" legend shows specific Watt output at any point in time. There is a time slider and playback animation you can also use to see the replay.

Panels A1 and A8 are the two closest to the house and the most shaded of all. A8 gets eastern sunlight upto 08:30AM and A1 gets western sun from 4PM. So those two are the gamble and get a pass on not being big performers. But in fairness, combined, they exceed the performance of any other single panel. So I was delighted to see that they are working and were definitely worth fitting day one.

A2 you can see is dead. No generation at all. Had this been a normal unoptimised string, the entire string would likely be dead. But the TS4 does its job and that dead panel is bypassed in full.

The lower 4 panels are 2 landscape either side of the E/W apex split. The A5 panel seems to be generating but less than its lower landscape sibling A6 or western siblings A3 & A4.

Life Lesson #2:

Optimisers solve problems but also hide them. We have had a dead panel here and never noticed it until the CCA was added. Whatever about detecting the dead panel, we would never ever have detected the underperforming A5 and that drop is not because of some shading issues.

The other pics show voltage (orange colours) and current (pink). Here we see that dead A2 has in fact 37V coming out of it but no current draw. The underperforming A5 is giving out a lower 21V versus 30-32 of its siblings. It's current output seems fine. AFAIK a basic multimeter VOC test on A2 will likely pass. So this could have been like this from the start.

There is one other shot showing the RSSI (Radio Signal Strength Indicator) and that helps highlight comms issues between the TAP and TS4s. The orange dot on each panel depicts panels that are directly connected to the TAP. Panel A6 however is shown with a line to indicate it is meshed with A5. That mesh behaviour helps larger strings to communicate with the one TAP over longer distances. You can also daisy-chain more TAPs if the array is much larger or spread across separate roofs.

In the end, I have to say I am delighted with this per-panel tracking. My installer will be visiting soon enough to change out the faulty panels. In the future I want to add 4-5 more panels on my north roof and again will rely on TS4s to let me see how well these north-facing panels work as part of my larger Franken-string.

In terms of the usability, Tigo have an app that you can use and also a cloud website. So it operates similar to most inverter monitoring.

The major annoyances:

* As you change day or switch display mode (power, energy, voltage etc), there can be a delay as it downloads the full data for the given day

* The standard account tracks only overall power generation per day (watt hours) and 15-minute granularity for live watt output. To get per-minute granularity and also voltage and current data, you have to subscribe to a premium account which costs USD $20/year. But they do give you a first month for free.

* Data is typically 20-30 minutes behind real-time. So its more suitable as a retrospective tool than live monitoring. But they could do a bit of effort here and get that lag down to say 5 minutes.

Hope this helps anyone curious about the Tigo CCA system.

10-10-20

Good information and kind of you to share your findings with us.

I bought the Hoymiles microinverters (MI) and it either has sub-1G or 2.4G comms which links back to their "DTU" management products, except the DTU's are expensive and lacking in connectivity to Home Assistant. They also upload to the cloud and the performance is poor with them.

Anyway a German team reverse-engineered the Hoymiles communications and produced a version of the DTU called openDTU and that works directly with Home Assistant to generate graphs, etc. It's installed onto a tiny USB powered device called an ESP32 with a special radio input, all coming to around 34 EUR for the device and casing. So the basic principal is the same as the Tigo CCA where you have a dash and you can see each of the panel and MI performance stats very easily, and there is no cloud element to have to deal with.

In all, a very handy tool if I ever suffer either a panel, DC cable or MI fault.

Much like yours the serial number for each MI must be taken off the label from the back of the inverter, so there's that to think about in advance, but you can just add inverters within seconds. You can also trim the inverter output down somewhat by setting a current limit per inverter. The integration then with Home Assistant is just the icing on the cake.

But yes, very questionable why a solar installer would not save the serial number of each optimiser given that they could use them for future troubleshooting and make their jobs easier!

cormacl

Thats fantastic. I was originally looking to go micro-inverter myself and had been thinking of dual-input Hoymiles. But it's very hard to find installers willing to do micro-inverters.

To be fair to the installer I had, almost nobody ever fits or needs to fit Tigo CCAs. I think the cobbled Franken-string nature of my 2nd string is what warrants it for as much curiosity as the need to understand what works well and what doesn't etc.

big_show

Thanks for this. As someone with 12 of these optimisers on my roof (i know, i know, madness, but its a split orientation string and i wanted the biggest solar setup i could get) I've thought about getting the cca but since my production seems good at the moment Ive left it.

I've no serials either so will be running a camera similar to yourself to retrieve them when it comes to it. This is great info to help have a better idea what to expect.