This is a lofty, expensive, but often sought-after goal for cruising catamaran owners. Have I achieved air conditioning with no generator or shore power? Somewhat, yes.
Air Conditioning is a Real Power Hog
To power air conditioning from your battery, solar, and inverter system requires major upgrades beyond the standard level of equipment seen on most cruising catamarans.
Required Upgrades to Run Air Conditioning from Solar:
Increase Solar Capacity: Add a solar arch with 2,000W on the rear and panels in every available location to reach a minimum of 3,000+ watts. Can some folks do it with 2,000W? Yes, but then maybe they can make less water and shower once a week—eww!
Increase Battery Capacity: At least 800Ah of 12V lithium phosphate for running air conditioning for a few hours, but for most of the night in one cabin or hull, more like 1,500Ah 12V plus is needed.
Upgrade Wiring, Fuses, and Shunts: Ensure the system can handle the increased power flow.
Upgrade Inverters: Install at least one large 4,000W continuous Victron Quattro 5000 or two Multiplus 3000W. A Victron Quattro 5000 can probably run two 220V air conditioners continuously (saloon and a hull), but nothing else—so don’t boil the kettle, or the system will overload and shut down.
For Leopard Catamarans: Upgrade the safety switching systems onboard to allow air conditioning loads to be turned on without requiring the generator.
Cost and Realistic Expectations
Once all these upgrades are completed, which could cost $50,000–$70,000 USD or more, how much air conditioning can you realistically use?
A system like this could run air conditioning for a few hours in the saloon and one hull.
Want more air conditioning? Then you need to replace the standard air conditioning systems onboard with ultra-efficient Mabru 12V air conditioning units or similar.
Important Considerations
Even if you pull power from a battery, you must be able to recharge it somehow. This may also require:
Larger Alternators: To recover some power while motoring around the corner to the next remote anchorage.
My Setup and Air Conditioning Usage on Coco, our 2013 Leopard 48
Major Electrical Upgrades I’ve Done:
Solar: 3,000W of rigid solar + 1,500W of faded flexi panels that need replacing. Don’t use flexible panels, but that’s another story.
Battery: 800Ah of Victron lithium phosphate.
Generator: Standard onboard 9kW Northern Lights unit.
Alternators: Two standard alternators on the engines.
Inverters: Two Victron Multiplus 3000W (one 110V and one 220V), each providing 2,400W continuous power. This setup provides great redundancy and supports global cruising power options. I can buy a 220V washing machine in New Zealand or a 110V one in the USA, making my boat more versatile for resale.
Additional Wiring, Fuses, and Shunts: Installed to support increased loads and ensure system efficiency. This area also adds up.
Leopard Generator Bypass: Modified to allow specific systems to run directly from the battery and inverter.
Air Conditioning and Other Performance:
I can run one air conditioning unit at a time for 2–3 hours, consuming about 20% of my battery on top of regular house loads. This means we wake up in the morning at about 30% battery after some use of air conditioning on a hot evening to help get our child to sleep, compared to 40-50% with no air conditioning usage. This assumes we have achieved full charge from a sunny day and have not made too much water onboard. It’s all relative.
If the next day isn’t perfectly sunny, I would need to run the generator for an hour or two.
Fully Electric Galley: Designed to support an electric cooking setup without relying on gas.
High-Capacity Water Maker: A 110V unit producing 30 GPH and used to make 150L (40 gallons) per day, powered by inverter and solar or generator. This ensures water redundancy if the generator fails.
My Upgrade Goal at the Time: I prioritized an electric galley, including a kettle, oven, toaster, and cooktop, while ensuring the water maker can also run without generator support.
Living on Anchor Without Air Conditioning
Most of the time, while living on anchor, we rely on natural ventilation, as boats tend to swing into the breeze. Marinas, where there is little airflow, become unbearably stifling, making air conditioning more necessary. Our cruising budget avoids marinas as much as possible. We also don’t need marinas, as we have sufficient power, water, and onboard comforts—helping to recoup some of our upgrade costs. Many cruisers run to marinas and comment on how nice it is to do laundry and take a decent shower, whereas we have these luxuries onboard already.
Leopard catamarans offer excellent airflow with the saloon front door. We lived for years onboard in the South Pacific without using air conditioning, but we’ve started using it more in SE Asia when trade winds stop, humidity rises, or when working onboard prevents simply cooling off by swimming. I am not sure i could buy any other catamaran without a saloon front door or forward cockpit.
I am also considering household split-cycle air conditioning units in the future because they are quieter and more cost-effective compared to marine systems but may rust away quickly. We are also moving towards household refrigeration and freezers onboard. Recently, we added a 140L (37-gallon) 220V chest freezer and plan to install a standard upright household fridge in the saloon. Marine 12V refrigeration tends to break down every 2–3 years, lacks auto-defrost, and struggles to maintain cold temperatures in the tropics. Our solar, battery, and inverter setup makes this transition possible.
Final Thoughts
Air conditioning from solar, batteries, and inverters is certainly achievable if you throw enough money at it. For significant air conditioning use without a generator, expect to spend up to $100,000 on top of an average base installation setup. However, you also get other benefits, such as quieter solar-powered living, reduced generator use, fewer oil and filter changes, an electric galley, generator redundancy, increased water production onboard, and battery storage, which helps run the boat overnight on passages with autopilot and navigation systems.
My favorite part of an electric galley? Kettle, toaster, and electric oven—because gas ovens feel like witchcraft! We use a fast, large 2200W kettle to make hot water for washing pots and pans. I really enjoy being able to make decent water without generator reliance. Redundancy has been my highest focus, as repairs in remote places are unbelievably hard and slow. My upgrades have mostly focused on comfort and redundancy so far.
For perspective, note that any upgrade spending will stretch your budget across multiple areas, such as additional sails, structural strengthening, redundancy, additional parts, and tools. So, it's not as simple as spending all your money on running air conditioning from solar and batteries.
P.S. We also have and love our dishwasher onboard.
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