Solar house generator I started DIY back in 2000 - My path from Trace to Xantrex (on FLA battery) to XW Pro inverters on Tesla Model S batteries

Fascinating build history — the jump from Trace to Xantrex is basically a timeline of the whole off-grid inverter industry in one system. Those old Trace SW series units were genuinely bulletproof; I've seen them running well past the 20-year mark.

The Tesla Model S battery migration is the bit I'm most curious about. Are you running the original BMS or have you bypassed it in favour of something like a JK BMS or Batrium? The cell chemistry on those early Model S packs (particularly the 18650 Panasonic cells) is well-understood now, but thermal management at meaningful discharge rates can still catch people out, especially in an enclosed battery room.

For anyone considering a similar path in the UK, it's worth noting the Tesla pack voltage ranges don't always play nicely with inverter charge profiles out of the box — the XW Pro is fairly configurable, but you'll want to spend time with the SCP settings to stop it pushing absorption voltage beyond what the cells actually want.

My own system is a more pedestrian Victron Multiplus-II setup on Fogstar 280Ah LiFePO4 cells, which feels almost boring by comparison. The main lesson I'd offer is that documenting every change as you go is invaluable — 24 years of incremental modifications means the current system and the original system share almost nothing, and fault-finding without records is a nightmare.

What prompted the move to the XW Pro specifically over something like the Victron Quattro at that power level? Curious whether it was cost, existing familiarity with the Xantrex ecosystem, or something the Quattro genuinely couldn't do.

@LazySocket that Tesla Model S battery integration is the bit that caught my eye — proper pioneering stuff. Most of us were still nervously eyeing Fogstar's 280Ah cells when people like you were already pulling packs from salvage yards and making them work.

The Xantrex chapter resonates too. I ran a similar generational hop on my motorhome setup before eventually landing on Victron kit, and there's something almost nostalgic about those transitional inverters — built like they expected a fight.

Curious what BMS solution you landed on for the Tesla modules? That's the bit that seems to trip most DIYers up when they move away from conventional FLA chemistry. The balancing characteristics are quite different to what those older systems expected to see.

Would love to see a wiring schematic if you've documented it — threads like this are exactly what this community needs preserving.

Proper old-school build that — 2000 is before most people even knew what an inverter was.

The Tesla Model S pack integration is the interesting bit for me. Those are NMC chemistry aren't they, so you're dancing with a tighter voltage window than FLA ever needed. Curious what BMS solution they landed on — that's always the sticky part with salvage EV packs.

Done something similar-ish in my motorhome (much smaller scale, Fogstar Drift LiFePO4 rather than salvage cells) and even with a proper purpose-built pack the Victron side needs careful config. Can't imagine mapping a Tesla BMS onto an XW Pro without some proper head-scratching.

What's the capacity they're running? Model S packs vary wildly depending on the donor car year.

Brilliant thread this — love seeing a system that's evolved over two decades rather than just being ripped out and replaced every few years.

@LazySocket the XW Pro is a solid landing point after that journey. How are you finding the Tesla packs in terms of BMS communication? That's where I've seen a few people come unstuck — the Model S modules need careful monitoring and some folks have had to run third-party BMS solutions alongside to get reliable SOC readings.

Also curious what capacity you're running total and whether you've had to do any thermal management in the battery enclosure. UK ambient temps are fairly forgiving compared to somewhere like Arizona, but those packs still have preferences!

Would love to see some photos of the installation if you've got any — always good to see how people have physically mounted the Tesla modules.

Really interesting to see that kind of system longevity. The Tesla Model S cells are a smart move — decent energy density and the packs are becoming more accessible as more salvage units come through. My own setup is far more modest (static caravan, Victron kit, Fogstar lithium), but the principle of upgrading incrementally rather than wholesale replacement resonates.

One thing I'd be curious about with the XW Pro on those Tesla packs — what BMS solution are you running? That's often the tricky bit with repurposed EV cells, getting the communication right between the pack and the inverter/charger. Victron's ecosystem makes that relatively straightforward with supported batteries, but I imagine the XW Pro integration required some custom work.