Mandatory Firmware Upgrade for S5 Dataloggers Upon Initial Installation

Technical Bulletin

December 31^st, 2025

Subject: Mandatory Firmware Upgrade for S5 Dataloggers Upon Initial Installation
Bulletin Type: Mandatory
Audience: Installers, Service Partners, Distributors
Products Affected: Solis S5-WIFI-ST Dataloggers
Firmware Version Required: V2013115 or newer
Effective Date: Immediate

Summary

Solis has identified a reliability issue affecting only the S5-WIFI-ST dataloggers when operating with older firmware versions. If the datalogger successfully connects to the Wi-Fi initially but remains on an outdated firmware version, it may experience irreversible failure after a day or less of operation.

To prevent this condition, all S5-WIFI-ST dataloggers must be upgraded to firmware version 2013115 or newer immediately after the first successful Wi-Fi connection.

Observed Behaviors

Two distinct scenarios may occur when first connecting the logger to the Wi-Fi:

1. Initial Connection Failure
   • If the datalogger fails during its first connection attempt, recovery is not possible.
   • In these cases, a replacement (RMA) is required.
2. Initial Connection Successful
   • If the datalogger successfully connects to Wi-Fi but is not upgraded immediately, it may fail after normal operation.

Important: Once this failure occurs, the datalogger will no longer be recoverable and will require an RMA.

How to Request the Firmware Upgrade

Contact Solis North America Service as soon as the datalogger is connected:

Phone: +1 (866) 438-8408 press 2

Email: usservice@solisinverters.com

Tell them you have an S5-WIFI-ST logger that needs a firmware upgrade to version V2013115 or newer and provide the logger Serial Number. The service team will perform the firmware update, which takes about 10-20 minutes. 

Important Notes

• This bulletin applies only to S5 dataloggers.
• The firmware upgrade is mandatory, not optional.
• Delayed upgrades increase the likelihood of datalogger failure.
• For any questions, comments, or concerns please contact the Solis service team