Anyone else running a Victron SmartSolar into a 48V system for EV charging — what MPPT size are you on?

Just upgraded my van setup to a 48V lithium bank (Fogstar Drift cells, 280Ah) specifically to feed a Type 2 EV charger on the driveway, and I'm trying to figure out if my 100/50 SmartSolar is leaving power on the table.

Running 4x 200W panels in 2S2P giving me roughly 72Voc into the controller, and on a decent day I'm seeing around 18-22A charge current — nowhere near the 50A ceiling. Problem is the Kangoo needs a minimum 6A AC draw to even negotiate a charge session, and the inverter's being fussy about whether it'll play ball with low solar.

Wondering if anyone's gone to a 150/70 or even a 250/70 and actually seen real-world gains, or if I'm just being optimistic about British weather doing the heavy lifting regardless of controller size. 🌧️

WattJane | Posts: 847

@KangooBuild nice build! The 100/50 will be leaving charge on the table if you've got panels to spare — it's capped at 50A charge current which on a 48V bank gives you roughly 2.4kW max input. For EV charging that headroom disappears fast.

I jumped from a 150/70 to a 250/100 on my 48V setup and it made a noticeable difference, especially on good summer days where I was previously clipping badly. The wider voltage window on the 250V models also opens up longer string configurations which helps with shading losses.

What's your total panel wattage and string voltage looking like? That'll determine whether you're actually hitting the 100/50's ceiling or if it's a non-issue in practice.

ExSquaddie97 | Posts: 312

@KangooBuild What's your panel array looking like — Voc and total wattage? That's really what'll determine whether the 100/50 is your bottleneck. At 48V nominal you're looking at a charging voltage around 54-58V depending on your BMS cutoff, so your MPPT headroom on the voltage side might actually be tighter than you'd expect. The 50A output cap is likely where you'll feel the pinch though — that's roughly 2.7kW max into a 54V bank. If you're running anything over 3kW of panels you're definitely clipping. A 150/85 or 250/100 would give you proper headroom, especially if you're planning to expand the array later. What inverter/charger are you running to actually deliver AC to the Type 2 socket? That side of the chain might end up being the real limiting factor before the MPPT even becomes the issue.

Brummie92 | Posts: 312

@KangooBuild cracking setup mate! Worth knowing the 100/50 caps you at 2,400W input on a 48V system, so depending on your panel array you could well be bottlenecked. What are you actually running panel-wise? If you're pushing anything north of 2kW STC you'd seriously want to look at the 150/70 or even the 150/85 — the extra headroom on a 48V bank makes a real difference when you're trying to top up an EV between sunny spells. I run a 150/70 into my 48V Pylontech stack and the difference in real-world harvest versus my old 100/50 was noticeable, especially on those partial-cloud days where the MPPT's working harder. Also check your VOC on cold mornings — the 100V ceiling catches people out.

ThingamyBob | Posts: 156

@KangooBuild running something fairly similar on my narrowboat — 48V bank feeding a slow EV charge overnight. One thing nobody's mentioned yet: have you looked at the 150/70 instead of jumping straight to the 150/85? Saved me a decent chunk and honestly for most static setups the 70A output ceiling is rarely the bottleneck — it's usually cloud cover doing the limiting long before the controller is.

Also worth checking what your battery BMS will actually accept on charge current, because on my Fogstar cells the BMS was the real constraint, not the MPPT.

What are your panels arranged as — series, parallel, or a mix? That'll change whether the voltage headroom on the 100-series is even an issue for you.

OakTom | Posts: 1,203

@KangooBuild Worth flagging that on a 48V system the 100/50 also limits your array voltage to 100V Voc — that's pretty restrictive once you start stringing panels in series for efficiency. I jumped to the 150/70 when I built my 48V setup and the extra headroom on both the voltage and the 3,360W input ceiling made a real difference, especially on decent summer days. If you're serious about pushing meaningful charge into an EV battery, the 150/85 or even the 250-series might be worth a look depending on how large you want to go with panels down the line. VRM logging will also show you exactly where you're hitting the ceiling currently — worth checking before committing to an upgrade.

KenCrane | Posts: 847

Good thread this. One thing nobody's mentioned yet — have you looked at the 150/70 as a middle ground? You'd get 3,360W potential on 48V and the higher input voltage ceiling gives you much more flexibility with series string configurations, which matters if you're running longer cable runs to the panels (common with driveway setups where the array isn't right next to the bank).

Also worth considering: EV charging draws pretty consistently rather than in peaks, so you really want that MPPT working hard across the full solar window rather than clipping on bright days. The 100/50 will frustrate you come summer.

@KangooBuild what panel array are you actually running wattage-wise? That'll tell us whether you're already leaving harvest on the table or if an upgrade would genuinely shift the needle. The Fogstar cells can certainly take the charge rate.

ColCrane | Posts: 412

@KangooBuild Worth checking your actual peak current delivery in VictronConnect — the 100/50 will hard-cap at 50A output regardless of what your panels can theoretically provide, so at 48V you're looking at a maximum of 2,400W throughput. If your array is anywhere near or above that, you're almost certainly clipping during peak hours. For EV charging that headroom matters more than most applications since you want sustained output rather than bursts. What's your total panel wattage? That'll tell you pretty quickly whether you're leaving meaningful charge behind.

EwanGreen | Posts: 634

@KangooBuild One thing worth considering alongside the hardware side — EV charging via an off-grid setup like this is going to be heavily weather-dependent, and a 48V system feeding a Type 2 charger will often struggle to maintain the minimum current threshold (usually around 6A) that the car expects before it simply stops charging altogether. Have you set up any kind of grid-tie or generator backup for cloudy spells? With Fogstar Drift cells you've got decent capacity, but if the MPPT can't keep up with draw, your BMS may be doing more work than you'd like.