Anyone else running a Renogy 40A MPPT flat-out all summer and quietly waiting for it to die?

Mine's been sat on the roof of my Transit doing its thing since April — two 200W panels in series, 12V lithium (Fogstar Drift 100Ah), and the Renogy controller just... works. Suspiciously well, actually.

Pulling around 40–55Ah on a decent British "sunny" day (read: partly cloudy with optimism), which is more than I expected given I'm parked under trees half the time like an idiot.

Anyone actually had one of these give up the ghost, or are they quietly more reliable than their budget price tag suggests? Genuinely torn between trusting it long-term or chucking a Victron SmartSolar on there before the inevitable betrayal.

Ha, I know that feeling @PeakNomad — there's something almost unsettling about kit that just quietly gets on with the job without demanding attention!

I've had the Renogy 40A running on my Sprinter for going on two years now, similar setup — pair of 200W panels and a Fogstar 100Ah. Touch wood it's been absolutely solid. The only thing I'd flag is keeping an eye on the temperature compensation settings heading into winter, especially with lithium. The default profiles aren't always spot-on for the Drift chemistry and it's worth cross-referencing with Fogstar's own charge specs.

Have you got the Bluetooth module on yours? The app's a bit clunky but it's handy for keeping tabs on things without crawling about on the roof.

Been running the same setup since last summer on my narrowboat — though I swapped one of the panels for a 250W and it's been pulling a solid 35-38A on good days without so much as a warm casing. I did crack open the Renogy app after about three months half-expecting some horror story in the logs, but nope, just pages of boringly healthy data.

Only thing I'd flag @PeakNomad is worth double-checking your temperature compensation settings if you're going into winter with that Fogstar — lithium profiles vary and the Renogy default can be a bit aggressive for some cells. Caught mine out last November. Nothing catastrophic, just not optimal charging.

Otherwise yeah, suspiciously reliable kit for the money. Touch wood 🤞

Been running the Renogy 40A on my shed setup for two seasons now — 3x200W into a 24V Fogstar bank — and honestly the most exciting thing that's happened is a firmware update I did voluntarily out of sheer boredom.

@DorsetBoater curious what you found mixing the 200W and 250W panels — I've always been slightly nervous about mismatched Voc on a single string but maybe I'm overthinking it? Would love to know if you noticed any real-world harvest difference.

The Renogy app is a bit rough round the edges but the hardware itself seems bulletproof so far. My only gripe is the temperature sensor lead is about 15cm too short for where I've mounted mine, which feels like it was designed by someone who'd never actually installed one. Minor complaint for kit that otherwise just quietly earns its keep.

Running a similar setup on my cabin — Renogy 40A paired with a Fogstar Drift 200Ah. Had it going since last spring with no complaints, which is exactly what makes me nervous about it.

My scepticism isn't so much about reliability as longevity. These things are built to a price point. Two seasons of solid performance is great, but I'd want to see 5+ years before I'd genuinely trust one over a Victron SmartSolar. The Victron's sitting on my boat and the data logging alone is worth the premium — you actually know what's happening rather than just hoping.

@SolarOwen curious what your Renogy's charge curves look like on the Fogstar bank — any signs of the absorption phase cutting short in warm weather? Had odd behaviour from cheaper MPPTs doing exactly that once temperatures climbed.

Ha, snap @PeakNomad — nearly identical setup here except I'm on a static caravan rather than a Transit. Two 200W panels, Renogy 40A, Fogstar Drift 200Ah, and it's been quietly beavering away since March without so much as a hiccup.

The thing that gets me is how boring it is, in the best possible way. I keep checking the app half-expecting something alarming and it's just... fine. Numbers look sensible, battery's happy, nothing overheating.

Only minor gripe is the Bluetooth dropping out occasionally on the app, which I know others have mentioned. Doesn't affect actual performance though.

Fingers crossed we're all still saying this come October — though @SolarOwen's two-season run is genuinely reassuring. Maybe we've all just been lucky with good batches? 🤞

Been running the Renogy 40A on my shepherd's hut since the build finished two summers ago — four 175W panels, 24V Fogstar Drift bank. What gets me is how boring it is. I'd half expected some dramatic failure by now, maybe a firmware quirk or a connector melting in the July heat. Nothing. Just quiet, consistent amps all day.

@RachelCooper the Bluetooth app is exactly that — just enough data to be useful, never quite enough to be satisfying. Still find myself checking it at odd hours like I'm waiting for something to go wrong.

Ran the Renogy 40A for 18 months on my shepherd's hut build — 3x175W into a 24V Fogstar bank — before swapping to a Victron SmartSolar 100/30 purely because I wanted proper Bluetooth logging and VE.Direct integration. The Renogy itself showed zero signs of dying. Pulled it, chucked it in the van conversion as a secondary controller, still running fine there.

The thing I'd watch on these is thermal throttling in high-ambient situations. Mine's mounted inside the hut wall and during a proper summer hot spell I noticed harvest dropping off mid-afternoon — turned out the controller housing was touching 58°C. Added a small standoff bracket to create an air gap behind it and the issue disappeared entirely. Worth checking if yours is against a metal skin like a Transit bulkhead, @PeakNomad.