How to add solar charging to a 48V/60V/72V E-Trike or Light EV (Boost MPPT vs Buck MPPT explained)

Been lurking on this thread for a bit and finally have a reason to chip in. Got an old 60V e-trike I picked up secondhand and I've been wanting to add a small solar top-up for when it's parked up outside during the day — mainly as emergency backup rather than a full charging solution.

From what I've gathered reading around, a standard buck MPPT (like most of the cheap Renogy units) won't work here because your panel voltage needs to be higher than the battery voltage for it to step down. So with a 60V pack, you'd theoretically need panels running at 70V+ input, which gets awkward fast with typical 12V/24V nominal panels.

That's where boost MPPT controllers come in — they can take a lower panel voltage and step it up to meet the battery. But I'm struggling to find anything purpose-built for 60V systems that isn't either Chinese-generic with dodgy specs or eye-wateringly expensive.

Has anyone actually got a boost MPPT running on a 60V or 72V system in the UK? Wondering if there are any controllers worth looking at that won't fry the pack. Victron obviously does quality kit but their MPPT range is all buck topology as far as I can tell.

Also — does anyone know if a buck-boost topology controller exists at sensible money? Seen a few mentioned on US forums but nothing UK-stocked.

@WheresMeWires31 good timing on this one — 60V systems catch a lot of people out because most common MPPT controllers are buck-only (step-down), meaning your panel voltage has to be higher than the battery voltage.

For a 60V pack you'd want panels wired to give you roughly 72-90V Voc to have enough headroom. That typically means two panels in series.

The alternative is a boost MPPT (step-up), which lets you use lower-voltage panels, but they're rarer and pricier — Genasun make decent ones but budget accordingly.

Key question: what's your actual pack's full-charge voltage? Nominal "60V" LiFePO4 usually charges to around 67-69V, so that's your real target ceiling for the controller.

What panel(s) are you working with? That'll help narrow down whether series wiring or a boost controller is the more practical route for your setup.

@WheresMeWires31 the dirty secret nobody tells you: a standard buck MPPT will just sit there doing absolutely nothing useful if your panel voltage can't beat your 60V pack — learned that the hard way with my garden office setup before I found a proper boost MPPT that could take a humble 40V panel and actually push charge into a higher voltage battery. 🤦 Worth checking out the Genasun GVB range or some of the Daly-based Chinese units on AliExpress if budget's tight — just make sure whatever you buy explicitly states boost capability rather than assuming, because the listings are absolutely riddled with misleading specs.

@VoltBarry is right, and I learned this the hard way on my motorhome build before I understood what I was actually dealing with.

The short version: your panel voltage has to be meaningfully higher than the battery voltage for a buck MPPT to function. It steps voltage down, full stop.

With a 60V pack sitting at say 67V fully charged, you'd need panels producing 80V+ at the controller input — which means either a boost MPPT (steps voltage up), or a series string of panels that can actually beat your battery voltage in real UK cloud conditions, not just peak STC figures.

Boost MPPTs exist but they're niche and pricier. Victron doesn't really do them. Worth looking at brands like Genasun for lithium-specific applications — they're not cheap but they actually work properly.

What cells are in that trike pack? That'll matter for the numbers.

@WheresMeWires31 60V is the awkward middle child of EV voltages innit 😄

Worth knowing there are dedicated boost MPPT controllers designed exactly for this — takes a lower panel voltage and steps it up to charge your pack. Brands like Genasun do some decent ones, though they're pricey. Some folk also use a standard panel feeding a boost converter inline, but that's getting DIY-hairy fast.

For a trike that's just parked up, even a modest top-up matters — solar hates sitting idle as much as the trike does. I run a small Victron setup on my garden office but the EV charging side is a different beast entirely.

What's your pack capacity? Might help folk suggest a sensible wattage target worth actually bothering with.