Generator or No generator, that is the question

[Gerrycooper56]

Originally Posted by MarkHopk

Hi Fellow Sailors,

We are putting together a energy system for our 40 ft Catamaran.
Please can we get your suggestions on the below:-

We will be powering, lights, laptop, navigation, fans and other day-to-day household needs.
We will on occasion utilise a washing machine, aircon and small low amp dishwasher.

Could we do this without a generator and by just having the right lithuim battery, inverter and solar panels? And if so How much AH lithium batteries and how much solar Watts would we need?

Thanks.

Hi, didn’t notice a watermaker in your equipment. Given you have a washing machine and dishwasher you may need to add a watermaker.

[MAJICDAN]

You will need a generator if you do not go to a dock at least every other night. No matter how many or how good of batteries that you have, you will have you will always have cloudy days that you will need a generator for charging just to keep up with the daily necessities. I usually travel 5000-6000 miles a year. Just the autopilot and electronics cause a large drain that is hard to keep up with on solar alone. You have to have a generator for backup battery charging and if you plan to run your air conditioning, Washing machine, Dryer, or a normal-sized watermaker. I have 1600 watts of solar and a split battery bank with a total of 2000 watts of golf cart house batteries. I have two masts and it seems as I always have at least one panel shaded. I have three 120 amp battery chargers for the house battery bank. I have a split bank 220V 8000-watt inverter that can run the washer, or air conditioner in one area, or watermaker on the batteries, but the toll is tremendous. I then have to run the generator longer to charge the batteries than if I were to run the generator to start with.

[Amapola]

Generators make life so much easier unless you are a marina Queen.

[lestersails]

Originally Posted by chrisr

while i don't disagree totally with the thought, what a lot of non-cat folk don't realise is even with the big roof space it is not always possible just cover it with solar panels

eg you need access to the boom (for reefing, maintenance etc)... there are hatches to open...toys to stow...control lines

And everything single thing you add above decks is another geegaw for an errant line to get hung up or snagged on at the worst possible time...

[Jon Hacking]

Originally Posted by MarkHopk

Hi Fellow Sailors, ... We will be powering, lights, laptop, navigation, fans and other day-to-day household needs.
We will on occasion utilise a washing machine, aircon and small low amp dishwasher.

Could we do this without a generator and by just having the right lithium battery, inverter and solar panels? And if so How much AH lithium batteries and how much solar Watts would we need?

Excellent questions, Mark. Everyone's thoughts on this will be different, so you don't have to emulate anyone, including me. But data will help you make a more informed decision. The short answer is Yes.

We decided when we bought Ocelot 20 years ago that we were going to be a battery boat, not a generator boat, & we still like that decision. I didn't want to have to maintain another engine. We put solar panels above the davits, cantilevered off our Targa-bar. Last year we replaced our 4x120W panels with 3x400W, since they're now so cheap ($0.50/W for guaranteed panels).

If you divide the wattage of your panels by 3, that will get you very close to the Amp-hours (Ah) they'll generate into your batteries in a sunny day (for horizontal panels in free-air in the tropics, taxes & dealer prep extra, your mileage may vary). So our 1200W should give us 400Ah (5KWh) on a sunny day. We could mount 2 more 400W panels above our bimini to bring us to 2KW, or 700Ah (8.6KWh) per day.

What you need to do is figure out your energy budget, & how often you're going to run your heavy-use appliances. Our son did ours, & published the results (poke around here & on nearby pages). We use about 150Ah/day including the watermaker & fridge/freezer but not the washing machine. You'll need to figure out how much your dishwasher uses (especially if it heats the water), & how much your air-con uses. The air-con will draw a lot initially, but it should taper off once things cool down, depending on your insulation & your temperature setting. FWIW, after spending 25 years in the tropics, the main time we've really felt we needed air-con is when we're in a marina & can't hang to the wind, but we're usually fine when we're anchored. So we carry one, but don't try to run it as our inverter is only 1,500W, enough for washer & power tools.

Once you know how much energy you'll be using/day, you need to decide how many rainy days you want to be able to withstand before turning on an engine (but you probably won't be running the air-con, your biggest consumer, on cloudy days). We currently have 540Ah of LiFePO4 (~430Ah usable) but if I wanted to run air-con, I'd probably double that.

You'll also need ancillary electronics, of course: a good inverter capable of powering all your needs, MPPTs for the panels, & BMS (with appropriate protection relays) for the LiFePO4s.

[perjan]

We have a 10.000BTU aircon running on a 2000W inverter, 315Ah lead batteries, 590Wp solar and 400W windgenerator.
The thing is, we only run the aircon for 15 minutes per day or so to only cool the sleepinghut.

Well, that’s what we plan to do. I just installed the aircon...

[Beniwood]

Check out Integrel Solutions technology. Co-developed with Nigel Calder, and just now seems to be coming to market in a big way. I plan to have this on my Catamaran, being built now. https://integrelsolutions.com/

[Dockhead]

Originally Posted by s/v Jedi

We have wildly different opinions on cruising... what you are doing is racing. I bet you take your dinghy belowdecks on passage, right?

Don’t worry, you’ll have enough solar... a couple years in the tropics will fix you haha

No, deflated and folded in its bag on the foredeck, just like when we're racing

Well, I'm not always (or even often) racing, but I just love to sail. What can I say. Making miles to windward is the peak sailing achievement. It is really satisfying when you can get your boat to go upwind. Lot of work, though.

[Dockhead]

Originally Posted by Beniwood

Check out Integrel Solutions technology. Co-developed with Nigel Calder, and just now seems to be coming to market in a big way. I plan to have this on my Catamaran, being built now. https://integrelsolutions.com/

This is a very good system.

But you don't need to spend that much money to generate a lot of useful power with your main engine. I get 2.5kW out of the ordinary school bus alternator my boat was built with - and I can be using the main for propulsion at the same time.

[David Mathis]

It seems much easier to just get a generator large enough to fulfill your needs. Under certain conditions, you can live comfortably without one, but wouldn't you rather be comfortable by simply starting the generator? You are correct in stating you can live at anchor without one. But is that true when you are at anchor and have several hot humid days with calm conditions, especially those with heavy overcast or rain? Having the ability to start the generator and get all the power needed 24/7 is worth the investment. My 9KW diesel genset was just rebuilt after about a bazillion hours. The rebuild was surprisingly cheap compared to replacing it. Get the generator, it is definitely worth the investment.

[Na Mara]

On a catamaran its hard to argue against just going solar. There is enough realestate for kW's of panels without additional structures. On a 40 ft with rigid Bimini you could probably fit 5kW of panels. Unless you are running household appliances and air-conditioning, even an overcast day of insolation will give you more than enough to meet your needs with that much capacity.

On a monohull, where panels really can interfere with the lines and operation of the boat, it's difficult to argue with a generator if you are living aboard. It's a big capital cost upfront, but a small 4kW generator charging say 4.5 kWh of batteries will allow charging only every third day or so on most boats using about one and a half litres of diesel each time. In context, my boat eats 0.8l of diesel every nautical mile on the engine. Three days of power for 2 nautical miles of dino-juice irrespective of weather and with no detriment to the lines or sailing ability of the boat is hard to argue with.

You can get similar functionality for significantly less capital cost (about a third) but significantly more running costs (10-15 times per kWh and around an tenth of the life expectancy) with a methanol fuel cell on a monohull so long as daily usage is under 1.8kWh. There are additional pros over the diesel generator (quiet, plug and play, diesel independent back up generation, practically zero maintenance, lighter, smaller) as well as additional cons (lower power output, additional fuel storage, difficulty sourcing fuel outside North Atlantic, no water heating, repair often involves replacement).

If I were living aboard full-time on a monohull I would go with a generator with a big battery bank and maybe a token panel or two. Otherwise, I would go with the fuel cell and a smaller bank.

[Pete Chambliss]

My limited cruising experience would say yes to a generator. Simply put, it is there when you need it with the push of a button, Fewer worries when the sun does not shine as well (depending on where you are going to cruise). I would also be concerned about a comparison of weight plus cost of retrofitting the battery. solar panel project. So there is my 2 cents worth

[Pete7]

Originally Posted by Beniwood

Check out Integrel Solutions technology. Co-developed with Nigel Calder, and just now seems to be coming to market in a big way. I plan to have this on my Catamaran, being built now. https://integrelsolutions.com/

Welcome to CF Do you have a connection to IST?

How many yachts do you know who have fitted this?

The only one I can think of is Distant Shores whose 10kw of AGM batteries failed in just over 2 years.

Pete

[Icarus]

Originally Posted by MarkHopk

Hi Fellow Sailors,

We are putting together a energy system for our 40 ft Catamaran.
Please can we get your suggestions on the below:-

We will be powering, lights, laptop, navigation, fans and other day-to-day household needs.
We will on occasion utilise a washing machine, aircon and small low amp dishwasher.

Could we do this without a generator and by just having the right lithuim battery, inverter and solar panels? And if so How much AH lithium batteries and how much solar Watts would we need?

Thanks.

You need a 6KVA generator.

[Attitude1]

Solar Generators are now available that have sufficient solar capability to power off grid living for everyone. Two of the most popular are Bluetti and Titan. Go to U Tube to review both brands. Before choosing your solar panels review the different choices and out[ut comparisons on U tube as well.
Please take the time to review a Dasiter 600 watt high power dc to dc boost converter, or several other competitive brands that allow you to significantly increase the power generation of the solar cells you intend to use. Personally I use a Bluetti 2000P to power my MacGregor 26x’s refrigerator, microwave, lights, evaporative cooler, winch, and other equipment 400 watts of solar panels. The Bluetti also powers everything in my Palamino 9001b truck camper including the 13,000 air conditioner.
There are larger generators available for those that need more power.them Both of these companies manufacture machines capable of stacking multiple LifePo4 batteries and innovative hacks are available on U Tube showing you how to charge them.