What size inverter do you actually need for a garden office?

Been running my garden office off a small off-grid setup for about a year now and still not sure I got the inverter sizing right. Currently got a 1000W pure sine Renogy unit which handles the laptop, monitors and LED lighting no bother, but the moment I plug in a small fan heater it trips out.

The heater's only rated 1200W so I thought a 2000W inverter would've been overkill. Turns out the startup surge caught me off. Now debating whether to just swap to a 2000W Victron Multiplus or stick with the Renogy and accept no resistive heating from it.

Curious what others are running. Do most of you just ban electric heating entirely and go for an Eco2 or similar wood pellet stove? Or have you sized up the inverter to handle everything? What's the sweet spot for a typical single-room office setup?

PYW_VanLife | 847 posts

@MarkAllen69 the thing people consistently underestimate is startup surge rather than running watts. Your 1000W is probably fine for a laptop and lighting, but if you ever want to add a small fan heater or a decent monitor setup, you'll hit trouble fast.

I'd generally say 2000W is the sweet spot for a proper garden office - gives you enough headroom without massively increasing your idle draw. Pure sine is absolutely the right call though, especially with laptops and anything with a variable speed motor.

What's your battery capacity looking like? Sometimes the inverter gets blamed when it's actually the battery bank struggling to deliver enough current that causes the issues. Worth checking your voltage under load before assuming the inverter's undersized.

YorkshireCamper | 234 posts

Slightly different use case here (static caravan rather than garden office) but the principle's the same. I went with a Victron 1600VA Multiplus and honestly wish I'd just jumped straight to a 2000VA — not because I'm regularly hitting the limit, but because having that headroom means the inverter runs cooler and more efficiently at my typical loads.

What's your kettle rated at @MarkAllen69? That's usually the sneaky one that catches people out. Even a "travel" 1000W kettle on top of a running laptop and monitor can push you surprisingly close to your ceiling, before you've even thought about a small fan heater in winter.

What does your actual peak draw look like on a typical day?

DonnaGibson67 | 412 posts

@MarkAllen69 worth thinking about what you might add down the line as well as what you're running now. I started with a 1000W unit in my office setup and within six months had added a small electric heater for the winter months - suddenly that wasn't enough at all!

I'd also consider your kettle if you ever fancy a brew without traipsing back to the house 😄 A decent travel kettle can pull 1000W on its own.

Personally I upgraded to a 2000W Victron and the headroom makes a real difference - not just for surge capacity as @PYW_VanLife mentions, but just general peace of mind. The inverter isn't working as hard constantly which I reckon helps longevity too.

What's your battery bank situation? That's often the real limiting factor rather than the inverter itself.