Solis S6 inverter and JK BMS Battery

Had the Solis S6 paired with a JK BMS on my narrowboat setup for about eight months now and it's been largely solid, but there are a few quirks worth flagging for anyone considering this combination.

The main thing to be aware of is the CAN bus communication between the two. The JK BMS speaks a Pylontech-compatible protocol by default, and the Solis S6 does support this, but you'll want to make sure you've selected "Pylon" in the Solis battery settings rather than leaving it on lithium generic — I wasted a fortnight scratching my head over why my charge voltages were drifting before someone on here pointed that out.

Once the comms are properly handshaking, the BMS takes charge of:

• Charge voltage limits
• Discharge cut-off
• Recommended current

...and the Solis obeys them faithfully, which is genuinely impressive at this price point.

One pedantic note: the JK's BT app shows slightly different figures to what the Solis is actually acting on via CAN. Don't panic when you see this — it's a display timing issue, not a real discrepancy.

I'm running 280Ah EVE cells in a 16S configuration, and the JK handles balancing during absorption beautifully. Active balancing at 2A isn't the fastest, but for a static setup it's perfectly adequate. Fogstar drift cells would be my recommendation if anyone's still sourcing.

Has anyone else tried pushing the Solis S6 with a higher capacity bank — say 400Ah or above? Curious whether the CAN comms remain stable at higher current draws, or whether others have seen any timeout errors.

@DevonDweller solid combo that. One thing worth watching with the JK BMS + Solis pairing is the CAN bus protocol mismatch — Solis S6 expects Pylontech protocol by default, and if your JK isn't configured to match that exactly you'll get communication errors or the inverter will fall back to dumb charging without BMS control.

In the JK app, set the protocol to Pylontech CAN and double-check the baud rate is 500K. Also worth noting the S6 can be a bit aggressive on the absorption voltage if comms drop — I'd set a hard cell OVP on the JK as a backstop rather than relying solely on inverter comms.

Been running a similar Victron/JK setup on my narrowboat for two years and the belt-and-braces approach on OVP has saved me twice when CAN comms glitched mid-charge.

@ExSquaddie49 oh don't get me started on CAN bus, spent three days arguing with mine before realising Victron would've just worked out the box — hindsight's a wonderful thing when you're 62 and freezing on a narrowboat.

@RetiredNurse49 that three-day rabbit hole sounds painfully familiar — I've been there with my boat setup too, just with different kit.

What I'd add, having run a similar arrangement in my garden office rather than a narrowboat, is that the cell balancing behaviour during absorption is worth keeping a close eye on. The JK is aggressive by default and I found it occasionally tripping the Solis on high-voltage events before the pack was properly top-balanced to begin with.

Spent a weekend with a bench power supply manually balancing my Fogstar cells before commissioning, and the whole system settled down considerably afterwards. Bit of a faff but genuinely worth the time upfront rather than chasing phantom faults for months.

If you're still seeing odd disconnects @DevonDweller, I'd rule that out before assuming it's a comms issue.

@DevonDweller eight months without major grief on a narrowboat is genuinely impressive given the damp environment these things operate in! One thing I'd add that nobody's mentioned yet — keep an eye on your charge voltage settings in the Solis if you're running LiFePO4 cells. The default profiles can be a touch aggressive and the JK BMS will eventually push back with a protection event if the two aren't properly calibrated to each other. I'd recommend logging your BMS data over a few charge cycles using the JK app and checking the cell voltage spread at the top of charge. Any cell regularly hitting its high voltage cutoff before the others suggests an imbalance worth addressing sooner rather than later. Narrowboats with their irregular charging patterns can mask these issues for months before they bite you. 🙂