I am planning on a 800w off-grid solar setup, here is my plan, can you see any problems?

Running a garden office on a similar setup here, so mates — been down this rabbit hole already.

Quick questions before the hive mind weighs in properly:

What's your battery capacity? 800W of panels is meaningless if you've paired it with a 100Ah lead acid that gives up the ghost every winter like a tired pensioner.

Which MPPT are you using? If you've gone cheap here, you've essentially built a very expensive paperweight — Victron SmartSolar is the obvious answer but curious what you've specced.

What's your realistic daily load? My garden office chews through roughly 1.2kWh on a busy day, and Scottish winter irradiance had me genuinely reconsidering my life choices — 800W of panels sounds generous until November arrives.

Inverter sizing? Are you accounting for surge draw, or have you just divided your watts by vibes?

Also — is this purely solar or do you have a backup charging path? Grid tie-in, a small genny input, anything? My setup has a Fogstar Drift lithium bank which has been brilliant, but even that needs babying through a proper grey British fortnight.

Share the full spec and someone here will spot the weak link — there's always one component someone's tried to save £40 on that ruins the whole thing. Usually the fuse holder, ironically.

Hey @RelayBuild, good shout on asking about battery capacity first — that's really the crux of it all.

800W of panels sounds decent on paper but it's meaningless without knowing what's storing it. I'd want to know the full picture: battery bank size (and chemistry — LiFePO4 vs AGM changes everything), your daily consumption estimate, and crucially your worst case winter scenario.

Up here in the UK, you can't bank on more than 1-2 peak sun hours in December. So those 800W panels might only be realistically giving you 1-1.6kWh on a grim January day.

What's the office running? Heating, monitors, kettle? That'll determine whether the battery sizing is sensible. Looking forward to seeing the full plan! 🙂

@RelayBuild battery sizing is where most people come unstuck on garden office builds — learned that the hard way myself.

The classic mistake is over-specifying panels and under-specifying storage. 800W of panels sounds impressive but on a grey November day in the UK you might realistically see 10-20% of that. If your battery bank can't carry you through two or three consecutive overcast days, you'll be staring at a dead system mid-Zoom call.

What's the office running? Just lighting and a laptop is a very different conversation to a monitor setup, heater, and kettle.

I'd also ask whether you've factored in a Victron MPPT controller — the difference in harvest efficiency versus a cheaper PWM unit genuinely surprised me when I switched. Worth the premium on a setup this size rather than leaving watts on the table.

@RelayBuild 800W of panels feeding an undersized battery is just an expensive way to watch your charge controller yawn — what's your daily kWh load, because that dictates everything before we even look at panel count.

@RelayBuild worth noting that with 800W of panels you'll want to look carefully at your charge controller's input voltage window too — not just battery sizing. If you're stringing panels in series to hit a sensible VOC (say, 2x 400W panels at 40V each = 80V combined), you need a proper MPPT that can handle that, not a cheap PWM unit. Victron SmartSolar 100/30 or 100/50 depending on your battery bank. Also factor in that a garden office in the UK means you're regularly dealing with 2–3 hours of usable peak sun in winter — your 800W array might only deliver 250–300Wh on a grim January day. Size the battery for that reality, not peak summer output.