Liveaboard solar electric boat

[john61ct]

That very relevant detail if posted in the first place, would likely have fundamentally altered the whole thread's responses.

[atlroofman]

Originally Posted by Nauti Cat

I’m looking for advice and suggestions on getting a solar/electric catamaran.
I would like to find a boat without engines to put a Torqueedo hybrid system in with solar panels for living on the hook.

And if anyone has experience living on the hook with solar-How much energy needs to be produced per day. I would be in south Florida and Caribbean so would need a/c 24/7 most of the year plus the usual appliances and tv.

Ideal boat would be 40-46’ at 25,000-30,000#, with a beam of 20-28’. Also I’d prefer to use the outboard version of their electric 55kw motors.

A 3000 watt solar array with $10,000.00 worth of lithium ion batteries with a soft start for the air cond compressor might get you 10 hours of air conditioning per day. For other uses above that you will not be in the Caribbean you will be in Dreamland.

[john61ct]

Whether or not a soft start is required depends on several variable factors, independent of the bank size.

The odds are well reduced by using LFP for the storage and a big cahuna inverter of top quality, but also

there are aircon systems designed to not require such at all, perform a very slow and gentle ramp-up that never gets close to the max watts required during peak operation.

[Nauti Cat]

Originally Posted by john61ct

That very relevant detail if posted in the first place, would likely have fundamentally altered the whole thread's responses.

Which relevant detail?
The budget? or the "moveable apartment"?

[john61ct]

budget

[GrowleyMonster]

Don't overestimate how much juice you get from a solar array. It will be a very small fraction of the rated output for a full day. You only get peak production during part of the day. Like maybe 3 hours. As the angle of the sun goes lower, oupput is reduced. If the shadow of a mast or even shrouds or spreaders crosses over a panel, its output is reduced. At higher temps, the output is reduced. As panels age, output is reduced. If a bird poops on your panels, output is reduced. Maybe with good insulation you could cool just one cabin for sleeping. I would stick with fans. With a big enough bank, you could maybe do this with the genset running a couple hours a day to make up the difference. Running both AC and a propulsion motor will be very expensive in terms of solar cost, battery cost, and diesel cost.



Will this boat have sails?

[Nauti Cat]

NO sails. Looking at 5Kwp solar system, hoping to produce 25kw per day on a sunny day. As far as aircon, several vessels have reported(like you mentioned)that they are able to manage partial cooling to one room at a time for less than 1kw so keeps it under 24kwh in a day, so would use some battery and run genset for an hour or two to make it up. So seems doable, but marginal and may need to run genset a little more, but at least won't have to run genset continuously like I do now.

[GrowleyMonster]

Originally Posted by Nauti Cat

NO sails. Looking at 5Kwp solar system, hoping to produce 25kw per day on a sunny day. As far as aircon, several vessels have reported(like you mentioned)that they are able to manage partial cooling to one room at a time for less than 1kw so keeps it under 24kwh in a day, so would use some battery and run genset for an hour or two to make it up. So seems doable, but marginal and may need to run genset a little more, but at least won't have to run genset continuously like I do now.

Oh yeah, don't forget to figure on cloudy weather happening often, sometimes for many days at a time.

[john61ct]

Originally Posted by Nauti Cat

Looking at 5Kwp solar system, hoping to produce 25kw per day on a sunny day.

A little optimistic, but near the equator in the ballpark as an average

> partial cooling to one room at a time

much more realistic goal

not including propulsion

> may need to run genset a little more, but at least won't have to run genset continuously like I do now.

BINGO!

that is really the key mindset in a very high consumption use case

Build it so you **can** run everything off genset

then add as much solar as you can stand, the goal being to reduce runtime and its costs as much as is practical.

Anything that can be done to reduce consumption, on the margins will have a huge ROI - and much faster - rather than adding more and more solar.

If most of your solar output is being consumed "live" or at least within 24 hours

that greatly reduces the bank Ah capacity required.

Those striving to get by on solar only / mostly are the ones need a bigger buffer.