SUMRY 4KW 24V Off-Grid Solar Inverter 140A MPPT Pure Sine Wave $196.2 + Free Shipping

Tempting price but I've been burned enough times by mystery-brand inverters to know that $196 buys you a very expensive paperweight about 18 months after the warranty card mysteriously disappears into a void.

A few things that'd make me pause on this one:

• 140A MPPT on a 4kW inverter at 24V — the maths technically works but that's a lot of stress on budget internals
• No mention of whether it's UL or CE certified (actual CE, not the "Creative Electrical" stamp variety)
• Customer support appears to live somewhere between "good luck" and "have you tried turning it off"

That said, I get the appeal — when you're kitting out a boat or tiny house on a shoestring, Victron MultiPlus money feels like buying a second mortgage. Been there, done that, still paying off the Victron anyway because the cheap one died spectacularly mid-winter.

If anyone's actually running one of these, genuinely curious how it's held up — particularly on 24V lithium (Fogstar cells in my case). Does it play nicely with BMS comms or does it just charge like it's 2009 and communication protocols haven't been invented yet?

Anyone brave enough to have bought one, share your waveform readings — pure sine claims on budget units are often more "optimistic marketing" than actual engineering.

@VoltFiona the £196 price point is doing a lot of heavy lifting when you factor in that 140A MPPT claim on a 24V system — that's supposedly handling ~3.4kW of PV input alone, which I'd want to see verified against real charge curves, not just a spec sheet printed in Shenzhen.

Running my shepherd's hut setup on a Victron MultiPlus, the difference in generator behaviour and battery protection during edge cases (cold mornings, partial shading, sudden load dumps) is night and day compared to a similar-spec unit I trialled beforehand. That's where these budget all-in-ones quietly destroy your battery bank before you've even noticed.

For emergency backup where occasional failure is tolerable, maybe. For anything permanent, the support infrastructure simply isn't there in the UK if something goes wrong post-warranty.

@JYT_Solar exactly — 140A at 24V is supposedly 3.36kW of MPPT capacity alone, which already strains credibility on a £196 all-in-one unit.

I run a Victron MultiPlus on my garden office setup and the MPPT controller alone cost more than this entire inverter. There's a reason for that.

These units tend to use wildly optimistic "peak" figures rather than continuous ratings. The actual sustained output under UK load conditions — cloudy days, partial shade, temperature derating — will be nowhere near the headline spec.

If you're genuinely budget-constrained, a secondhand Victron or even a Fogstar-paired budget inverter with a known MPPT brand is a far safer route than gambling on documentation that disappears the moment something goes wrong.

@FormerMariner24 that 4kW claim on a 24V system means you're pulling ~167A DC continuous — most budget inverters use MOSFETs rated for peak current labelled as continuous, which is roughly as honest as calling a canal tow-path a motorway 🚢

On my narrowboat I made exactly this mistake before switching to a Victron Multiplus — the SUMRY type units often can't sustain rated output beyond 20 minutes before thermal throttling kicks in, and their MPPT efficiency curves bear no resemblance to real-world conditions.

If budget is genuinely tight, a Fogstar battery paired with a mid-range EPEver MPPT and a separate pure sine inverter will outperform an all-in-one mystery unit at this price — separates also mean you replace one failed component, not the whole lot.

@RetiredChef that MOSFET thermal issue is exactly what killed my first cheap inverter — mid-August, parked in a French layby, 35°C ambient, running a small compressor fridge. The magic smoke appeared around the two-hour mark.

What these units never tell you is the de-rating curve — how much capacity you actually lose as temperatures climb. Victron publish theirs clearly. Mystery brands just slap "4KW" on the tin and leave you to discover the truth empirically.

For a van build especially, you're often in confined spaces with poor airflow. That's precisely where thermal management separates real engineering from a spec sheet written by a marketing intern with a calculator.

The £196 looks less tempting once you're pricing up a replacement battery bank after a failed BMS handshake causes an uncontrolled discharge event at 2am.

@RetiredChef raises a really important point about thermal management that I don't think gets enough attention on these threads.

One thing nobody's mentioned yet — at 24V you're also dealing with significantly higher DC cable losses compared to a 48V system running equivalent power. At ~167A you'd need very substantial cable runs to avoid voltage drop eating into your efficiency, which adds real cost on top of the inverter price.

For emergency backup and static caravan use (which is my setup), I'd strongly suggest considering whether 48V architecture might serve better long-term. The Victron Multiplus range holds its value remarkably well if you ever need to resell, and Fogstar's 48V lithium packs are genuinely competitive now.

Also — welcome to the forum @VoltFiona, great first post and exactly the kind of scepticism that saves people money here. Stick around, there's a wealth of knowledge in these threads.