Anyone else running a small MPPT just for emergency backup — worth it or overkill?

Been putting together a basic emergency backup setup at home after last year's power cuts. Nothing fancy, just want to keep the router, a few lights and phone charging going if the grid goes down for a day or two.

Currently looking at a 200W panel (probably Renogy) into a 100Ah LiFePO4 (eyeing up a Fogstar Drift), controlled by a Victron SmartSolar 75/15. The Victron feels like it might be overkill for such a modest system — but I keep reading that undersizing the controller causes grief, and the Bluetooth monitoring on the Victron is genuinely useful for a beginner.

Total estimated load is roughly 150–200Wh/day on backup. The panel would be semi-permanently mounted on a south-facing garden wall at maybe 50–60° tilt (not ideal, I know, but it's what the wall gives me).

Is there a sweet spot between "cheap rubbish" and "full Victron kit" for a setup this small, or is the SmartSolar 75/15 actually the sensible choice even at this scale?

@Clive1978 Running a dedicated small MPPT for exactly this purpose on my shepherd's hut — a Victron SmartSolar 75/15 paired with a single 200W panel and a 100Ah Fogstar Drift LiFePO4. Total overkill for router/lights/phones? Possibly. But the Victron's load output with configurable low-voltage disconnect means I don't need a separate BMS relay for basic protection.

Key consideration people overlook: panel orientation matters more in winter when you actually need backup most. My hut panel is steeply pitched (60°) specifically for low December sun angles.

If budget's tight, a Renogy Wanderer 30A does the job for considerably less, though you lose Bluetooth monitoring. For a home emergency setup where you're not watching it daily, I'd actually argue the Victron's remote visibility via VRM is worth the premium — you'll know state of charge without going outside.

@LutonCamper already covered the Victron angle well. For a garden office setup like mine I went a different route — paired a small Renogy Wanderer 30A with a single 200W panel and a Fogstar 100Ah LiFePO4. Runs the router, LED strips and laptop charging no bother at all.

Honestly for what @Clive1978 is describing, 30A is probably overkill — you could get away with a 10 or 15A controller easy. Just make sure whatever you pick has proper low-voltage disconnect if you're using lithium, some of the budget MPPTs are a bit sketchy on that front.

Worth every penny once the grid went down last winter. Didn't even notice the outage for the first hour.

My cabin's been running a dedicated Victron 75/15 for the "oh no the kettle's the least of my problems" circuit for two years — router, a couple of LED strips, phone charging, absolutely zero regrets.

One thing nobody's mentioned: keep your backup panel separate from your main array so a fault on one side doesn't take down everything simultaneously. Learned that the hard way when a dodgy MC4 connector took out my whole setup during Storm Isha.

Also worth wiring it to a small Fogstar Drift LiFePO4 if budget allows — the self-discharge on old lead-acid batteries means you'll reach for it during a blackout and find it flatter than a Norfolk road.

Useful thread — doing something similar in my van but been wondering if the same logic translates to a home backup situation.

One thing nobody's mentioned yet: what panel wattage are you pairing with these small MPPTs? The 75/15 keeps coming up but I'd imagine it matters whether you're throwing 100W or 200W+ at it.

In the van I've got a Victron SmartSolar 100/20 handling a couple of 175W panels and it feels slightly oversized for the load, but that headroom has proved genuinely useful in winter when every amp counts.

For a home emergency setup focused on router/lights/phones — would a smaller cheaper unit like the Renogy Wanderer be adequate, or is the Victron reliability worth paying for when it's genuinely emergency-critical kit?

Given my van setup I've basically already solved this problem by accident 😄

Running a Victron 75/15 on a dedicated 200W panel feeding a 100Ah Fogstar Drift — keeps my EV charging monitor, leisure circuit and comms gear alive independently of the main system. The key thing people overlook is keeping it genuinely separate from your primary battery bank. When the main system has a fault (and it will eventually), you don't want your backup dragged down with it.

@LDVNomad — yes it absolutely translates to home. If anything it's easier on a fixed install because you're not fighting weight and space constraints.

For @Clive1978's use case, a 75/15 plus even a modest 100W panel would comfortably cover router, LED lights and USB charging indefinitely through most UK weather.

Don't overthink the panel size — oversizing the battery matters more here.

Got a similar setup running in my garden office — Victron 100/20 feeding a single Fogstar LiFePO4 battery. Small panel on the roof keeps it ticked over year-round.

The key thing I'd add: size the MPPT for expandability, not just your current panel. I started with one 100W panel and ended up adding another six months later. If I'd gone smaller I'd have been buying another controller already.

For a home emergency circuit @Clive1978, I'd also think about what actually matters when the grid drops — router and a few USB ports don't need much at all.

@LDVNomad the van-to-home translation absolutely works — I stumbled into exactly this realisation during a road trip planning session when I noticed my motorhome's backup circuit was more reliable than anything I had at the house.

Running a Victron 100/20 on a separate 100Ah Fogstar Drift lithium in the van, purely for "keep the essentials alive" duties. The whole thing ticks along invisibly until you actually need it.

The key thing I'd flag for a home setup: keep the battery dedicated to this circuit only. The moment you start leaning on it for other stuff, it's never fully charged when the grid actually drops. Learned that the hard way parked up in the Cairngorms when I'd drained it running a fan heater the night before and woke up to no comms.

@Clive1978 the "overkill" framing bothers me slightly, because it implies there's a tidy threshold between necessary and excessive — there isn't. What matters is your worst-case load calculation, done properly. Total up every device's wattage, multiply by your longest expected outage duration, then size your battery accordingly, then size your MPPT to that battery's charge requirements. I did exactly this for my motorhome before translating the same logic to a home backup setup. A correctly-sized small MPPT isn't overkill — it's just correct engineering. An undersized one, however, absolutely is a false economy.