Solar panel and AC advice

[jt11791]

Originally Posted by Projectfreedom

Greetings,
Planning to buy my first sailboat this Winter and need to rig it for living in the Florida summer heat.
Any advice on outfitting and cost for a 35' sailboat would be very helpful.
I guess the main question is how many solar panels will I need and how many batteries will I need to pump my cabin with AC for at least 8 hours?

Thank you

To be clear and simple, you cannot fit enough solar on a 35' boat to run A/C for 8 hours, probably not even 2 hours. A/C is a huge energy hog and very few boats try to run A/C without shore power or a generator. Those that try have very large solar arrays, which require a lot of space (think big catamaran), they also need large battery banks and power inverters (again lots of space and $$$). Even with all that, these boat only run A/C for a few hours at night.



I live on a 54' boat. I have a 670W solar array, a fairly large size for a modern cruising monohull boat, and a large lithium battery bank. I cannot run my A/C without the generator (or shore power). There are catamarans near me with double my solar and they can't run A/C either.

[moseriw]

5 Tons of Batteries and 250 m² of Solar Panels?
AC on a boat? Your kiddiing eh?
That is, without shore power or an always running generator, simply stupid.

[LoudMusic]

Originally Posted by motion30

Ok so. Your options are a regular AC air conditioner powered by a generator. Or.... We have been experimenting with DC air conditioners my knowledge is based on the 12 volt unit made in China. There are two options a 12000 BTU unit that draws around 40 amps DC. My friend with 2000 watts of solar could not support that full-time in the daytime. Second option is the 12 volt 7000 BTU air conditioning good for most sleeping quarters. That draws around 20 amps DC. And it's a portable with the big battery bank and around 1500 watts of solar. I think for you the AC air conditioner and the Honda portable generator would be best. I've been living aboard full-time since 2010. I am not in the marina but anchored out. I find there's only a few nights in the summer that I really suffer. I have a bunch of DC fans and find those to be mostly okay. Your comfort level will vary

40 Amps for a 12K BTU unit? I don't believe it. I think you'd be lucky to run that on 70 Amps.

[moseriw]

One shall sail away to join nature. So what the f is an AC good for?

[Sailmonkey]

Originally Posted by LoudMusic

40 Amps for a 12K BTU unit? I don't believe it. I think you'd be lucky to run that on 70 Amps.

The Mabru 12vdc 350 btu cabin AC has a published draw of 20 amps. So ummmmm......yeah.

[motion30]

Originally Posted by Sailmonkey

The Mabru 12vdc 350 btu cabin AC has a published draw of 20 amps. So ummmmm......yeah.

Yes these are exactly those units,. my friend on the 46th sailboat with 2000 watts of solar could not support the bigger unit. Full time. He could run it all day off of solar but then he had never charged his batteries. There was some supply parts like the water pump that were not up to the task. But all in all the smaller unit seems promising. Would be enough to cool a bedroom at night. I think in my little group we have ordered five more. Of course I am in South Florida

[Sailmonkey]

Originally Posted by motion30

Yes these are exactly those units,. my friend on the 46th sailboat with 2000 watts of solar could not support the bigger unit. Full time. He could run it all day off of solar but then he had never charged his batteries. There was some supply parts like the water pump that were not up to the task. But all in all the smaller unit seems promising. Would be enough to cool a bedroom at night. I think in my little group we have ordered five more. Of course I am in South Florida

Yes, but 20amps @ 12v for 350 btu is WAY different than 40amps for 7000btu. It’s an actual believable number.

[motion30]

Originally Posted by Sailmonkey

Yes, but 20amps @ 12v for 350 btu is WAY different than 40amps for 7000btu. It’s an actual believable number.

It may have actually been 24 amps 12 volts , but that was the actual measured number. And it did cycle off and on throughout the night.

[Bullshooter]

Have fun everyone, but I believed you have been trolled here. But by all means share the data among yourselves.

[motion30]

Originally Posted by Sailmonkey

Yes, but 20amps @ 12v for 350 btu is WAY different than 40amps for 7000btu. It’s an actual believable number.

I just talked to my friend and got a revised amperage number on the 7000 BTU unit. He is saying 25 to 30 on that particular unit. But like I said it does cycle

[Sailmonkey]

Originally Posted by motion30

I just talked to my friend and got a revised amperage number on the 7000 BTU unit. He is saying 25 to 30 on that particular unit. But like I said it does cycle

I just looked at the specs on the am running site......I’m amazed ! Now I need to figure out how their 350 btu model pulls 20a and their 7000 btu model pulls 24a.

I may need to eat a hat.

[motion30]

Originally Posted by Salastfnkey

I just looked at the specs on the am running site......I’m amazed ! Now I need to figure out how their 350 btu model pulls 20a and their 7000 btu model pulls 24a.

I may need to eat a hat.

Look at the right revised figures that I posted 25 to 30 amps DC 12 volt

[Sailmonkey]

Originally Posted by motion30

Look at the right revised figures that I posted 25 to 30 amps DC 12 volt

Which is still quite amazing. And it should be for the price they’re asking. I now need to figure out how they’re doing it.

[moseriw]

20A(h) x 24 = 480Ah. Battery discharge max 60% = Rack 800 Ah.
Recharge Solar 400 Wp = 2,8 m² gives me around 12A, max. 19A (out of WP 33A!!!)

So what are you talking about. You want an energy system that covers your needs at easy and without calculating every hour how much you get/use.


Even without Ac you will need 12-15 A per hour. and it does not matter much if you stay on anchor or sail. "But I need only 8A!" - yes, be lucky and calculate with 12-15A tt recharge.

[moseriw]

If you need AC on board stay at home and live your adventures as "couch potato"