Anyone else running a cheap Chinese MPPT off a single 100W panel? Sharing my results after 3 months

Been running a Wanderer 30A MPPT clone I picked up off eBay for £18 delivered — one of those generic blue ones with the LCD screen. Paired it with a single 100W poly panel I got secondhand for a tenner, feeding into a 100Ah leisure battery out of a scrapped caravan. Total outlay for the charge side was about £28, which felt like a laugh compared to what Victron et al want.

Honest results so far: on a decent sunny day in September I was seeing around 5–6A going in at peak, which felt about right. Now we're into the grey months I'm lucky to see 1–2A by midday. The controller itself hasn't caught fire, the LCD still works, and it's been left outside in a waterproof box through some proper wet weekends without complaint. Surprised me, genuinely.

My worry is whether it's actually doing proper MPPT tracking or just acting like a PWM in disguise — I've seen a few threads elsewhere suggesting some of these budget units are basically PWM with a fancier label slapped on. I haven't got a decent way to test it properly with what I've got on hand.

Has anyone done a proper back-to-back comparison, or got a clamp meter setup that could help figure out whether the tracking's legit? Curious what others are running on the cheap end and what real-world amps you're pulling.

@Foggy interesting experiment but I'd be cautious calling those units genuine MPPT — most in that price bracket are PWM circuits with MPPT labelling slapped on the firmware display. Real MPPT conversion topology costs money to implement properly.

I ran a similar generic unit for about six weeks in my Transporter build before replacing it with a Victron 75/15. The difference in harvest on overcast UK days was significant — we're talking 15-25% more usable charge in diffuse light conditions, which is exactly where proper MPPT earns its keep.

With a single 100W panel your losses aren't catastrophic, but once you scale up the maths changes considerably. The Victron 75/15 street price is around £65-70 — on a budget yes, but it's a one-time purchase that'll outlast three generations of clone units and actually does what it claims.

Ella1994 | 📍 Yorkshire | Posts: 847

@GoldenTrekker is spot on about that — I've got one of the same blue units sitting on my bench right now and popped it open out of curiosity. The inductor inside is comically undersized for proper MPPT switching. That said, @Foggy I'd be genuinely interested in your actual charge numbers — does the voltage on your panel drop noticeably under load? A real MPPT should be pulling it down toward the panel's Vmp (usually around 17-18V on a 100W poly). If it's just sitting close to battery voltage you've basically got a PWM with a fancy screen. Not saying it's useless mind, just worth knowing what you're actually getting for your £18! 😄