100% Off-Grid Solar Air Conditioner DC 24V/48V Solution for Remote Areas and Energy Saving Cooling

Interesting topic — been thinking about this a lot lately for the narrowboat.

Running AC off solar on a 48V system is theoretically doable, but the real devil is in the detail. A decent 9,000 BTU DC inverter unit pulls maybe 400-600W at full chat, which sounds manageable until you factor in a cloudy British summer (and let's be honest, that's most of them).

On my boat I've got 800W of panels feeding a Victron Multiplus and a Fogstar 200Ah LiFePO4 bank. I'd be nervous relying on that for active cooling without seriously upsizing the battery capacity first. You'd want at least 400Ah realistically, probably more if you're not moving and topping up via alternator.

A few questions worth discussing:

• Has anyone actually run one of these dedicated DC units vs. just using a standard inverter AC unit?
• What's the real-world COP difference?
• Are the dedicated 48V units (I've seen some Midea and Gree ones floating about) actually more efficient than running a Daikin through a quality inverter?

The remote cabin use case makes more sense to me than narrowboating honestly — static installation, south-facing roof, no shade issues. For boats it's trickier.

Would love to hear from anyone who's actually deployed one of these rather than just theory-crafting. Real data always beats spec sheets!

@SmartSolar_Master the load profile is what kills most people's calculations. A 9,000 BTU unit might pull 700–900W running, but the compressor start surge can hit 3–4x that momentarily — your inverter needs genuine headroom, not rated peak.

On my shepherds hut setup I run a 24V Victron Multiplus-II and learned quickly that continuous watts ≠ realistic sizing.

Key things worth modelling properly:

• Duty cycle — compressor rarely runs 100%, more like 40–60% in UK summers
• Battery bank sizing for overnight thermal mass retention
• MPPT capacity — Victron SmartSolar 100/50 minimum for meaningful solar contribution

The genuine 48V DC inverter units (some Midea-based ones) are more efficient than AC-coupled solutions, but sourcing quality units in the UK without warranty support remains the weak point.

What's your current battery chemistry? That changes the conversation significantly.

Really good point from @BordersExplorer about load profiles. What catches people out on narrowboats specifically is the start-up surge — even DC inverter units can spike briefly, and if your battery bank isn't sized generously enough you'll see your BMS trip before the compressor even settles.

Also worth considering: canal orientation matters enormously. Moored east-west versus north-south changes your solar harvest significantly mid-afternoon when you'd actually want the cooling most.

Has @SmartSolar_Master looked at whether shading from trees along towpaths is factored in? I'd honestly suggest logging actual irradiance data for your typical mooring spots before committing to a system size. A 48V setup is definitely the right direction over 24V for these loads though — lower current means much saner cable runs on a boat.

Really interesting thread. On my motorhome I've been looking at this exact problem — specifically whether a 48V inverter-driven unit like the ones Victron-compatible setups can support would actually be viable without running a generator through the afternoon peak.

One thing nobody's mentioned yet: orientation and shading losses. On a motorhome (and presumably a narrowboat) you're rarely perfectly south-facing, and even partial tree cover can cripple output exactly when you need cooling most.

Has anyone actually data-logged their real solar yield during summer afternoons vs the AC draw simultaneously? I'm curious whether the numbers hold up in practice rather than just on paper. What monitoring setup are people using — Victron Cerbo GX with the data logging, or something simpler?

Has anyone actually run one of these units through a full UK summer on a static caravan setup? That's my situation — south-facing roof, 48V Victron system, Fogstar lithium bank.

My concern is the shoulder months more than peak summer. July might be fine with decent generation, but what about that week in May when it's somehow 28°C and your panels are only doing 60% because of cloud cover?

@WattLiz curious what inverter route you went down — are you looking at a dedicated 48V DC unit or running through an existing inverter? I've seen some of the Midea DC inverter split units advertised but not sure how they actually behave under partial load conditions.

What's a realistic minimum battery capacity people are working with before this becomes viable day-to-day rather than just in ideal conditions?