UPS for home office — solar charged

Been running something similar in the van for ages now. Dead handy when the grid's dodgy or just want to cut costs during peak hours.

My setup's pretty straightforward — Victron MPPT controller feeding a 200Ah LiFePO4 bank, then a Victron Multiplus II inverter/charger handling the switchover. Works seamlessly for the office gear. Laptop, monitors, and the router all stay powered through cloud cover or the odd outage.

Key things I'd think about:

Battery size — depends on how long you need to run. Office is usually lighter draw than you'd think, but factor in spikes. I went bigger than needed because it's cheaper per Wh that way and leaves headroom.

Inverter — make sure it can handle your peak load and has good surge capacity. Don't cheap out here. That Multiplus II isn't the smallest investment but the automatic switchover is brilliant. No faff with manual swapping.

Solar — UK sun's not great but enough in summer. Worth oversizing the array a bit since you're not desperate for every watt. Fogstar panels are solid locally if you want to support UK makers.

Monitoring — honestly, the VRM portal on Victron gear is worth its weight in gold. See exactly what's happening, plan accordingly.

Only real downside I've found is the mental load of monitoring it, but that goes away quick. Saves a fortune on leccy bills too.

What's your current power draw like? That'll shape the whole thing.

That Victron combo is solid. The MPPT's efficiency really shows when you're trying to squeeze every watt from limited roof space on a van setup.

Worth considering your battery chemistry though — if you're cycling daily during peak hours, LiFePO₄ will outlast lead-acid by years, even if the upfront cost stings. I switched my garden office to a 5kWh LiFePO₄ system last year and the cycle depth difference is night and day. With lead-acid you're fighting voltage sag under load anyway.

One thing to watch: make sure your UPS (assuming you mean the inverter's pass-through capability?) can handle the switching speed. Some older chargers take a beat to recognise mains failure. The Victron Multiplus handles it cleanly, but cheaper units can cause brief dropouts on sensitive equipment.

What's your battery capacity looking at, and are you planning AC or DC-native loads? Makes a difference to efficiency losses.

The real value here is having that buffer between your solar input and your office load. I've got a similar setup in the van—Victron MPPT feeding a small LiFePO4 pack, then a Victron MultiPlus inverter handling the UPS side of things.

Key thing @ThingamyBob62 and @CliveBaker are hitting on: the MPPT efficiency genuinely matters at smaller scales. You're not losing 15-20% to a cheap PWM controller, which adds up fast when your panel real estate is limited.

For a home office specifically, I'd suggest prioritising the inverter's transfer speed. You want <10ms switchover so your monitor doesn't flicker and your router stays online during cloud cover. The MultiPlus handles this well. Pair it with a decent 24V LiFePO4 bank (Fogstar or similar) and you're looking at a system that'll comfortably run 500-1000W continuously while charging from your panels.

Battery sizing's the usual calc—what's your actual office draw? If it's just a laptop and router, 5k

Nice thread! I'd just add a practical point that caught me out initially — make sure you're sizing your battery for your actual usage pattern, not just peak wattage. I assumed a smaller capacity would do for my home office setup, but I hadn't factored in those grey sky days when solar input drops off sharply.

Worth considering a hybrid approach too, if your budget stretches to it. I've got my UPS paired with a smaller 48V lithium battery that handles the daily office bits, then a larger lead-acid bank for longer backup periods. Bit of overkill maybe, but it takes the pressure off the smaller battery and extends its lifespan considerably.

@ThingamyBob62 — have you noticed much difference in your van setup between summer and winter charge times? I'm curious whether the reduced winter sunlight affects your ability to run peak-hour shifting like you mentioned.

One last tip: get a decent monitoring system from the start. Being able to see exactly what you're drawing really changes how you think about consumption. Game changer for working from home.

Great thread! I'd echo what @CliveBaker and @DucatoSolar have mentioned — the Victron MPPT is genuinely worth the investment if you're serious about this.

One thing I'd add to @Emma1981's point about sizing: don't just look at your peak office power draw. Think about duration too. If you're working 8 hours but the sun's only decent for 6, you need enough battery capacity to bridge that gap, especially during winter months when solar generation drops off a cliff.

I'd also recommend investing in a decent battery management system (BMS) if you're going lithium — the protection and monitoring is worth every penny. And if you're in an older house with dodgy wiring, consider a small isolation transformer between your solar setup and sensitive kit like computers. Saved me from a nasty surge event last year.

What battery capacity are you looking at, @ThingamyBob62? That'll help folks gauge whether this approach might work for their situation too.