Batteries
Are Pylontech batteries swelling, and what should I ask my installer?
Some South African owners have reported swollen Pylontech US-series modules and disputes over warranty claims, mainly on public forums. That is community reporting, not proof of a failure rate. If you own or are quoted Pylontech, insist on a working BMS communication link, correct charge voltage settings, an authorised installer and kept logs, and treat any swollen module as a safety issue.
Updated 26 October 2026 · Tariffs quoted are the 2026/27 municipal year (from 1 July 2026) unless stated.
What has been reported
- A 2025 Power Forum thread describes several US3000 modules swelling on a Deye inverter setup.
- Another thread describes warranty claims declined for over-charge or over-discharge, with owners disputing whether settings were to blame.
We have not tested these batteries and do not publish failure rates. The reports are useful because they show what makes a claim easier or harder.
If a module looks swollen
- Switch the system off at the battery breaker and stop using that module.
- Do not open, puncture or move it more than needed.
- Photograph it and call your installer and the distributor.
- Keep BMS logs (BatteryView or the inverter’s history) for the claim.
Questions to ask before you buy any battery
- Is this battery on my inverter’s compatibility list, and will you connect the communication cable?
- Which charge voltage and cut-off settings will you use, and where do they come from?
- Who is the South African warranty holder (Solar Deity / Pylon SA service), and do I need to register for the 7-year path?
- Has your company handled a warranty claim on this brand, and how long did it take?
Many buyers now weigh field life and local support above price for this reason. See the battery comparison for how roughly ten brands compare on warranty, cycles and expansion.
Quick questions
Is Pylontech a bad battery?
Not necessarily. It is widely installed in South Africa, which is partly why more reports appear. Install quality and settings matter a lot.
Is a swollen lithium battery dangerous?
Treat it as a safety risk. Isolate it, do not use it and have it checked and replaced through the warranty channel.
What voids a battery warranty most often?
Missing BMS communication, wrong charge settings, installs by unauthorised people, and operating outside the temperature limits.
Official SA service stance (read this)
Solar Deity is the authorised South African Pylontech service partner. An Official Statement on Power Forum (topic 34279) from the Official Service Center for Pylon SA says:
- Standard warranty is five (5) years from purchase, extendable to seven (7) years on successful product registration.
- Claims are decided on BMS telemetry, physical inspection and install/operating conditions — not on failure alone.
- Cell swelling is not automatically evidence of a BMS fault; prolonged operation outside limits can degrade cells even when the BMS worked as designed.
Some consumer guides still quote a SA warranty letter as 7 years / 10 years if registered. Ask for the letter that applies to your serial numbers, and book claims through the official service channel rather than informal WhatsApp groups.
Sources
- Power Forum: Official Pylon SA warranty / diagnostics statement (topic 34279)
- Solar Deity — authorised SA Pylontech service
- Power Forum: Pylontech US3000 batteries swelling
- Power Forum: Pylontech swollen batteries