Guide / Overview: Boost MPPT Controllers (Sunopen H20TB) for 48V/60V/72V EV & Tricycle Solar Builds

Really interesting thread — I've been down a bit of a rabbit hole lately looking at non-standard MPPT options, mostly because my shepherd's hut build is on a conventional 12V Victron setup, but I've been helping a neighbour spec out a solar-assisted electric tricycle and the boost MPPT angle came up almost immediately.

The Sunopen H20TB keeps popping up in research but there's surprisingly little real-world data on UK installs. Most of what I find is either Chinese forum posts or American EV conversion stuff where the voltage requirements and riding conditions are totally different.

A few questions I'd love to see covered if anyone has hands-on experience:

• Thermal performance — these units seem to run warm. Anyone derating them in summer or enclosing them in a weatherproof box?
• Panel compatibility — are people pairing these with standard monocrystalline panels or going flexible? For a tricycle build weight obviously matters
• 72V battery charging accuracy — how tight is the termination voltage? Some cheaper controllers are sloppy enough to either undercharge or stress cells

The boost topology is genuinely clever for low-panel-count mobile builds where you can't stack enough panels in series to hit your battery voltage. For my hut I didn't need it, but I can absolutely see the use case here.

Would be good to get some UK-based data points rather than just specs off AliExpress listings. Anyone actually running one through a British winter with meaningful load?

@SophieHobbs74 the rabbit hole gets deeper — once you've seen a £40 Chinese MPPT pull 98% efficiency on a 72V e-bike pack, it's hard to justify the Victron premium for every single build 😄

Worth noting though: these boost-topology controllers (like the Sunopen H20TB) are genuinely useful where your panel voltage sits below your battery bank — classic shepherd's hut scenario if you're running two panels in series on a cramped roof and want 48V output.

Key watch-outs from my narrowboat tinkering:

• No reverse polarity protection on most of these units
• BMS communication is essentially nonexistent
• Thermal management is... optimistic

For your 12V Victron hut I'd leave well alone, but if you ever fancy a secondary 48V leisure circuit, pairing one of these with a Fogstar 48V pack is surprisingly capable for the money.

@SophieHobbs74 snap on the shepherd's hut — mine's 12V Victron too but I keep eyeing up the weird stuff 😅

Genuine question though — does the Sunopen H20TB do anything useful for a conventional static build or is it really only worth it once you're on a higher voltage EV-style pack?

My gut says stick with Victron SmartSolar for the hut (BT monitoring alone is worth it) but I've got a van conversion on the back burner and wondered if something like this makes more sense there, especially if I end up going 48V on that one.

@RetiredChef that efficiency figure is wild btw, would want to see that tested against a Victron 100/30 before I believed it fully

@SophieHobbs74 the boost topology is what makes these genuinely interesting — unlike conventional MPPT which can only step down from panel voltage to battery voltage, a boost controller works the other way, letting you run a relatively low-voltage panel array into a higher-voltage battery pack. Practically speaking, that's why they're everywhere in the e-bike and tricycle world: two 24V panels → 72V pack, no problem.

The Sunopen H20TB specifically handles up to around 100V input IIRC, which gives you decent headroom with a couple of panels in series.

Worth noting for a 48V EV charging context (which is my main interest): the charge profile matters enormously. Many of these units ship with lead-acid defaults and you'll need to dig into the programming to get lithium curves right — Fogstar cells especially won't thank you for a badly configured absorb voltage.

@SophieHobbs74 same boat — got a pretty bog-standard Victron SmartSolar setup on the static caravan and it does the job fine, but these boost controllers are genuinely interesting for edge cases.

The bit that gets me is the potential for low-voltage panel configs charging higher voltage banks. Practically useful if you've got a pile of 12V nominal panels lying around but want to run a 48V system — normally that's just not viable with conventional MPPT.

Never touched the Sunopen units personally but curious whether anyone's got real UK weather data on them. Efficiency figures from Chinese spec sheets on a sunny Shenzhen rooftop are one thing, pulling decent numbers through a Scottish November is another matter entirely 😅

Anyone running these through winter yet?

@SophieHobbs74 really glad you posted this — I've been scratching my head over the same thing for my van conversion. The boost topology angle is what's got me curious: theoretically you could run a smaller panel array in a tight roof space and still hit a higher battery voltage?

Practical question though — has anyone actually measured the efficiency losses on these Sunopen units under real UK conditions? We're not exactly blessed with strong irradiance here, and I'd imagine marginal gains disappear quickly on a cloudy November afternoon. My Fogstar 200Ah on the van is 12V but I'm spec'ing out a potential 48V shepherd's hut build and wondering whether something like this is worth the risk over a proven Victron unit.

Are there any UK suppliers actually stocking these, or is it purely AliExpress territory?