Tigo TS4-A-O Optimizer Failure and Zero Voltage: What Tigo's Site Says and What We Saw

Our array stopped producing and the TS4-A-O units we checked read zero volts. What Tigo's web pages say, and what we saw.

Last reviewed 2026-10-13.

What the manufacturer documents

• Tigo's TS4-A-O product page (text read on 2026-10-13) describes optimization as a Flex MLPE function available as an add-on unit (TS4-A-O), for designs with unequal string lengths, mixed orientations or areas of mismatch, and for installation in shaded areas. It says that in addition to optimization the TS4-A-O enables module-level monitoring and rapid shutdown in compliance with NEC 2014, 2017 and 2020. (tigoenergy.com)
• The product page lists the TS4-A-O as suitable for up to 725 W solar modules, with a configuration of 1 module per TS4, working wirelessly with the TAP and CCA, and under configuration it lists 'Required CCA + TAP'. It lists 'Meets US NEC rapid shutdown requirements' and a '25-year warranty' among its features and benefits. (tigoenergy.com)
• The product page's system text says Tigo's Cloud Connect Advanced (CCA) is the data hub, that the CCA connects by RS485 cable to the Tigo Access Point (TAP), which communicates wirelessly with the TS4 units, and that module-level data can be viewed in the Tigo Energy Intelligence monitoring portal. (tigoenergy.com)
• The product page lists, for the TS4-A-O, several datasheets (including a TS4-A-O 725 W datasheet and a TS4-A-O datasheet for Australia and New Zealand), quick start guides and an installation manual. We do not cite their contents; the page links them, and this note does not reproduce any installation or replacement procedure. (tigoenergy.com)
• Tigo's downloads page (text read on 2026-10-13) lists a warranty document titled 'Limited Warranty for TS4 products, TS4-A, TS4-X Platforms, Cloud Connect Advanced, RSS Transmitter, Tigo Access Point, RSS Signal Detector and PST-G (as of January 31, 2025)'. It also says warranty documents for other products purchased before January 31, 2025 are located elsewhere on the page. We do not cite the warranty terms, and we have not recorded which document applies to our units. (tigoenergy.com)

What happened to us

• The owner said that one day they woke up and the array was giving no solar: no voltage from the entire array, on their ground-mount system. He said he was not sure what happened and that the optimizers had worked perfectly since installation for many months, if not weeks. (video)
• He said they had been troubleshooting for about an hour. He first said he thought all of the optimizers had died, then corrected that he had only got to about three of them. (video)
• With a voltmeter on the output of one optimizer, the owner read no voltage. He said that when he let go of the probes he saw a spike of about one millivolt, and he said it had been like that for about two or three days. (video)
• With the panel disconnected from the optimizer and the meter on the panel's own two leads, the owner read about 38.3 volts. He said he had not tested whether that panel was good. (video)
• On one unit the owner showed a worn area with a small burn mark and stains. On the unit's top or bottom side he said it looked melted and was still hot, and said that unit 'failed drastically'. He said he hoped that unit was the problem but that all of the units he had checked read no voltage. (video)
• He said that, as of the recording, four out of four of the units he had checked had failed, and that the array has more units than that; he guessed eight, nine or ten panels. He said they would remove the optimizers and reconnect the panels directly to get the array charging again. He did not say what the result was. (video)
• He said the management system for the optimizers was not set up, so he had no monitoring data on the units. (video)
• In the 2024 installation video the owner installed the units because some panels on the array are shaded at times. Reading a unit's label aloud, he gave 1500 V (UL) and 1000 V (IEC) system voltage and 80 V, 15 A and 700 W. He said installation started on the morning of July 15 and that it had been cloudy and stormy since. (video)
• In that video he mounted the units on the side edge of the panel frames because the frames have only a shallow lip, and said he understood the manufacturer recommends the top edge. He said he had no other option and did not expect much of an issue. The 2025 video says the units were on the bottom of each array; where they sat at the time of the failure is not recorded. We do not know whether mounting position has any bearing on what we saw. (video)

What Tigo's web pages state compared with what we saw

What we did not verify

• This note reports what Tigo's web pages say and what the owner said in the two videos. It is not a diagnosis, and we do not know why the units read zero volts or why one looked melted.
• Burned, melted or failed electrical hardware is a hazard. This note gives no steps for inspecting, testing, reconnecting, removing or replacing anything: follow the manufacturer's documents and use a qualified person.
• Tigo's datasheets and manuals are hosted on a third-party content network that we did not cite. This page uses only the text of Tigo's own website pages, read on 2026-10-13, which may change.
• We did not record the part number, revision or serial number of our units. Tigo's product page lists several datasheet variants, including a 725 W one, and which one matches our units is not recorded.
• The owner's readings are approximate and come from a handheld voltmeter on camera. We do not know the meter model or range, or the sunlight at the time, and the reading of about 38.3 V is on a panel's leads, not a test of the module.
• The 2025 video says four out of four checked units failed. We do not know how many units the array has, how many were checked in the end or how many failed, and this note says nothing about how often TS4-A-O units fail.
• The figures the owner read from a unit label in the 2024 video are what he said aloud on camera. They are not our measurements and are not checked against a Tigo document here.
• The 2024 video is older than the 2025 failure video and than Tigo's web pages as read on 2026-10-13, so what Tigo's pages said in 2024 may differ.
• This note does not use the owner's early production readings from the 2024 video, and reports none of them.
• We do not know whether Tigo support was contacted and have not described or assessed any warranty process.
• Not recorded: the panel model, the string layout and the system voltage, the inverter or charge controller the array fed, and the number of panels and strings; the purchase date and seller of the units and the date the lost production was first noticed; the weather before and on the day of the failure; whether the 38.3 V reading was taken on the same panel as a zero reading; whether a rapid shutdown initiator was installed, whether the units were ever registered in Tigo's monitoring and any app or firmware readings; whether the seller was contacted and what either Tigo or the seller said; how many units showed marks and whether any connectors or cables were affected; and whether the planned removal and reconnection happened and what followed.

Questions and answers

What does Tigo say the TS4-A-O does?

Tigo's product page says it provides optimization, module-level monitoring and rapid shutdown, as an add-on unit for each module, working wirelessly with the TAP and CCA.

What module size does Tigo's product page list?

It lists the TS4-A-O as suitable for up to 725 W solar modules. The owner read 700 W from a label on camera; we have not checked that against a document.

Does Tigo's product page describe a fault indicator or fault code for the unit?

Its text describes none. Tigo lists datasheets, quick start guides and an installation manual for the unit, which we did not cite.

Why did our units read zero volts?

We do not know. The owner described the readings and what he saw on one unit in the video, but did not establish a cause.

Does this mean TS4-A-O units commonly fail?

No. This note describes one array as the owner described it and says nothing about how often anything happens.

What should I do if my array stops producing?

This note gives no steps. Follow the manufacturer's documents and use a qualified person.

Sources

• Tigo Energy TS4-A-O product page (web text, read 2026-10-13)
• Tigo Energy downloads page (web text, read 2026-10-13)

Videos this comes from

• Solar Array Not Producing Power? TS4-A-O Optimizer Failure, Zero Voltage & Burned Units – Array not producing: zero-output readings on several units and marks on one unit
• Tigo TS4-A-O review | Optimization, Monitoring & Rapid Shutdown – Installing the TS4-A-O optimizers on our array, 2024

Follow along

New troubleshooting notes and comparisons come from our videos. Subscribe on YouTube or join the Discord. We do not collect email addresses on this site.