Solar panel and AC advice

[captainwd40]

Sorry that you ask a simple question here and get so many neigh sayers.

Your question is quite simple:

AC draws 10 amps x 8 hours = 80 amps if all you run is the AC.

80 amps x 120 volts ac x .707 = 6787 volt amps (pseudo watts)

6787 volt amps (pseudo watts) ÷ 48 volts DC = 141 amps DC

If you install two 48 volt 100 Amp Hr lithium ion batteries in parallel connected to a 10 kilowatt inverter you should be fine ...... charging the batteries however is another story.

What goes out must come back in and with solar you will only have 12 hours in full bright sun to accomplish
the task. So 6787 pseudo watts ÷ 12 hours = 566 watts per hour.

If you install two 48 volt lithium ion batteries in parallel connected to a 10 kw inverter with 700 watts of solar panels (although 900 watts .... two 450 watt solar panels would better) connected to a MPPT charge controller you should be fine cool and happy ...... and all this can found priced and purchased on Amazon.

Cheers and happy sailing!

Respectfully,

Captainwd40

[Sailmonkey]

Originally Posted by captainwd40

Sorry that you ask a simple question here and get so many neigh sayers.



Your question is quite simple:



AC draws 10 amps x 8 hours = 80 amps if all you run is the AC.



80 amps x 120 volts ac x .707 = 6787 volt amps (pseudo watts)



6787 volt amps (pseudo watts) ÷ 48 volts DC = 141 amps DC



If you install two 48 volt 100 Amp Hr lithium ion batteries in parallel connected to a 10 kilowatt inverter you should be fine ...... charging the batteries however is another story.



What goes out must come back in and with solar you will only have 12 hours in full bright sun to accomplish

the task. So 6787 pseudo watts ÷ 12 hours = 566 watts per hour.



If you install two 48 volt lithium ion batteries in parallel connected to a 10 kw inverter with 700 watts of solar panels (although 900 watts .... two 450 watt solar panels would better) connected to a MPPT charge controller you should be fine cool and happy ...... and all this can found priced and purchased on Amazon.



Cheers and happy sailing!



Respectfully,



Captainwd40

Now for the easy part.....where does one place a pair of 450 watt panels on a 35’ monohull?

[SeaStory]

Originally Posted by Sailmonkey

Now for the easy part.....where does one place a pair of 450 watt panels on a 35’ monohull?

I also want to know where you get 12 hours of full sun year round.

[Sailmonkey]

Originally Posted by SeaStory

I also want to know where you get 12 hours of full sun year round.

And fully direct?

Should we be discussing how to install a pair of solar trackers for 450watt panels on a 35’ boat? Don’t forget the thrusters too.....that’ll keep shading from the rig from falling over the panels.

[Bullshooter]

What's that sound, you ask?

Oh, that's just the OP snickering about how he uncorked his little fake diatribe a week and a half ago, (and 5 pages ago) and it's still rolling on.

Well played, Project Freedom...

[Indefatiguable]

Maybe this has been mentioned already, I didn't read all 5 pages.

For a reasonably small interior boat you can get a full sized cooler, put 2 bricks of ice in it (or cubes but they don't last as long obv), cut a 3" dia hole in both sides (long way thru) to put a thin walled PVC pipe through, then rig a fan or blower into the pvc pipe. the blower is the only amperage draw and the ice cools the air running through it.

Of course repurposing an old radiator or heat exchanger etc can cool the air better. The ice blocks in a decent 3 day cooler in south flo/keys etc will last from sundown till sunup. Put a flexible hose/duct on the output end of the air flow and run it up into your berth if it's extra hot that day. Ran this type of system in a converted school bus when we did flordia in 2019.

this is wayy cheaper then trying to run a solar setup for air conditioning, just have to buy ice before hand. Don't forget to rig a drain hose to the little hole on the cooler.

Could also do a 15-20' (depending on location and thermocline) hose to a copper coil stack that you dunk underwater with another hose back up to the boat, eliminating the need for ice. Not sure if that'd work better or worse, just a thought.

[evanw25]

Originally Posted by SeaStory

I also want to know where you get 12 hours of full sun year round.

So do I. We quote 6-7 hours here in SoCal.

[evanw25]

Originally Posted by flightlead404

The charger itself is probably very inefficient. Rather than simply plugging in the regular mains charger into an inverter driven 120v AC outlet, which also has significant inefficiencies, I would find a 12v adapter that plugs right into the laptop. That is going to be a much more efficient way to power the laptop.



Also, I wound consider cutting off any "cigarette lighter" type plug on the end and wiring a dedicated sealed connector and a separately fused dedicated outlet. That 12v adapter will become corroded over time, and generally they are pretty crappy.



I'm not far enough along in my own research on this to recommend a connector yet, perhaps there is a specific type recommended by ABYC or similar I'm not sure. There are way smarter people on here than me who probably know the answer to that.

High amp USB connector is what you need. Blue Seas Systems makes a double port connector. You will need your power source to be conditioned— specifically pure sine wave— for computers and other sensitive gear to properly work if you stick to running these items off your inverter.

[Statistical]

Originally Posted by captainwd40

Sorry that you ask a simple question here and get so many neigh sayers.

Your question is quite simple:

AC draws 10 amps x 8 hours = 80 amps if all you run is the AC.

80 amps x 120 volts ac x .707 = 6787 volt amps (pseudo watts)

6787 volt amps (pseudo watts) ÷ 48 volts DC = 141 amps DC

If you install two 48 volt 100 Amp Hr lithium ion batteries in parallel connected to a 10 kilowatt inverter you should be fine ...... charging the batteries however is another story.

What goes out must come back in and with solar you will only have 12 hours in full bright sun to accomplish
the task. So 6787 pseudo watts ÷ 12 hours = 566 watts per hour.

If you install two 48 volt lithium ion batteries in parallel connected to a 10 kw inverter with 700 watts of solar panels (although 900 watts .... two 450 watt solar panels would better) connected to a MPPT charge controller you should be fine cool and happy ...... and all this can found priced and purchased on Amazon.

Cheers and happy sailing!

Respectfully,

Captainwd40

You won't get 12 hours of output out of solar panels. Depending on the latitude and local weather 4 to 6 hours of peak sun equivalent per day is more realistic.

Note sure what the .707 discount is. In fact due to mppt losses and inverter losses you should probably use a 1.1 multiplier.


So 120V * 10A * 8 hours = 9600 Wh * 1.1 (for losses) = 10,500 Wh. So with 5 hours of insolation that would only require ~ 2 KW of solar panels. Less and you either need a generator or expect to charge the batteries by the engine each morning (or accept running the AC less than 8 hours a day).

[Linguini]

Hi!

Let me ask, what is your goal? Do you want it to be freezing cold or just a few degrees below the outside temperature? I know some, maybe most, Americans like it ice cold inside :-). That's something you'll find very difficult and expensive to achieve.

But, if you buy a sailboat and the first thought is AC, maybe it's the wrong investment?

If you just want a few degrees less, there are solutions that can work in a cabin.

First, throw all the wood out of the cabin. Second, rebuild the bunk so you have plenty of air under the mattress. Third, take a nano coating and apply it to the inside of the walls. Fourth, you will have some condensation. The nano coating drains well. collecting it and pumping it out.
Fifth, for the front cabin you need only 3K BTU to cool it down by 5-8 degrees Celsius. Such mobile system you can put on the front hatch, similar to a smaller refrigerated truck.

https://dcpowersales.com/project/ac-...rk12-and-rk14/

Works! But I don‘t want to sleep in such a .....

Alternatives: Hammock with mosquito net, move to Maine, get used to heat :-)

Actually I experiment with low energy AC for the front hatch. But just to get a slightly cooler breeze into the cabin. It works.

You have to choose translate.... https://www.linguini.eu/aircondition-fuer-kleinkreuzer/

170 Watts power consumption incl. the pump energy.

Keep Cool!