Anyone else using cheap Chinese PWM controllers or is it false economy?

Had one of those generic 30A PWM units on my shepherd's hut build for about 18 months. Paid about £12 off Amazon, can't even remember the brand — it had some made-up name like "SolarMax Pro" or something equally meaningless.

Honestly? It mostly worked. But the stated specs were fantasy. Claimed 30A, I wouldn't trust it above 15A sustained. The temperature readings were wildly off and one morning in February it just... stopped. No obvious reason. Panels fine, batteries fine.

Switched to a Victron 75/15 MPPT after that and the difference in charge efficiency was immediately noticeable, especially on overcast days. Paid for itself quicker than I expected given how grey it gets here.

I think the real question is what you're protecting. If it's two leisure batteries running some LED strips and a phone charger — maybe the risk is acceptable? But if you've got decent batteries (I'm running Fogstar Drift lithiums now), putting a dodgy controller in the chain feels daft. The weakest link and all that.

A few things I'd flag:

• Rated current vs actual current — assume it's half whatever they claim
• No low voltage disconnect worth trusting — nearly killed my old AGMs
• Heat management is usually rubbish on the cheap ones

Curious whether anyone's had better luck with the slightly pricier Chinese MPPT units — the EPever Tracer range gets mentioned a lot. Are those a middle ground worth considering or still a gamble?

@AnneWatson yeah the fake brand names are a dead giveaway — "SolarMax Pro" 😂 they're all the same board from the same Shenzhen factory just with different stickers

ran one on my static for about a year, seemed fine until it quietly stopped regulating properly and I didn't notice for weeks. batteries took a hammering

the £12 looks less clever when you've cooked a £150 battery

switched to a Victron SmartSolar MPPT and it's just... boring. works every time, talks to my phone, doesn't randomly decide to stop doing its job

PWM vs MPPT is a whole other argument but even if you're sticking with PWM, spend £30-40 on something with actual documentation and a brand that'll still exist next month

Has anyone actually compared the efficiency losses between a cheap PWM and something like a Victron BlueSolar MPPT on a small system? Genuinely curious whether the conversion gains justify the price jump for a modest garden office setup — mine's only running about 200W of panels.

I get that the fake branding is a red flag, but surely for a simple 12V system with matched panels the PWM inefficiency is somewhat predictable at least? The unknown quality of the components worries me more than the topology honestly.

@ZFS_OffGrid what were you actually seeing in terms of controller temperature? One thing I've noticed is these units seem to run hot even at modest loads, which makes me wonder about the longevity of the capacitors more than anything else.

@SaltyRigger yes, extensively. Running a Victron SmartSolar 100/30 on my static caravan alongside a cheap PWM on a secondary shed circuit — same panel wattage, same battery bank voltage, similar orientation.

The MPPT pulls genuinely 20-30% more usable energy on overcast days. Sunny summer days the gap narrows, but in the UK that's not exactly your typical scenario is it.

The maths is straightforward:

• PWM wastes anything above battery voltage from the panel
• MPPT harvests it

On a small 100W panel the absolute gains are modest. Scale up to 400W+ and the efficiency argument becomes financially obvious within a season or two.

The real issue with the cheap units isn't even efficiency — it's that their stated current ratings are fantasy figures. That "30A" controller is doing well to handle 18A continuously without the mosfets cooking themselves.

@WhatsAFuse65 that side-by-side comparison is genuinely useful data — most people just argue from theory.

My experience: ran a no-name 20A PWM in the van for eight months before swapping to a Victron SmartSolar. The difference wasn't just efficiency numbers — it was reliability. The PWM started throwing false full-charge readings in winter, so my batteries were chronically undercharged without me realising. Nearly killed a Fogstar 100Ah lithium that way.

The real false economy isn't the upfront £12. It's when you're parked on a Welsh hillside in February with no heating because your controller quietly lied to you for three weeks.

For a shepherd's hut with grid backup nearby, @AnneWatson, maybe the risk is tolerable. For anyone depending on it as genuine off-grid or emergency backup — spend the extra £80 and sleep properly.