Air Conditioning Unit for Use with Solar

[markguthrie]

I starting on the process of putting in a solar system so that I can be on the hook and run the AC for one stateroom overnight without running my geny.

I will be buying a new AC just for this. Any input? My contractor is recommending this one. Velair 16k BTU, 110v. I have gotten input that I should get a DC. I have 12V.

Mark
St. Pete FL
Navigator '53 stink pot

[LoudMusic]

I run a 12000 BTU Dometic from 120v on battery that is charged from solar during the day.

You'll need an inverter that can sustain that amount of power output without risking failure. At this time I have an older Magnum 2812. It runs at about 50% load when running the aircon along with other boat services.

You'll also need quite a lot of battery. These airconditioners will consume about 120A when running. I have 1200Ah of lithum at 12v.

And quite a lot of solar to charge it back up during the day. I have 2100w.

I do not have enough battery or solar to feel comfortable running the aircon 24h/day. Primarily solar. I think another 300Ah battery, and probably another 3000w of solar, would be necessary to just leave the aircon on all the time.

We use it to cool down the master cabin for a few hours before bed.

[dlentz]

That Velair unit is one of the most efficient ones out there. It's a variable speed compressor with a brushless motor blower. It's start up amps are around 2 amps, and that is the issue that most inverters and small generators have issues with a "conventional"ac. I believe Velair claims you can run their 27k btu unit on a 3.5kw genset. You can run the i16 on low fan and it will produce around 4k btu at the proportional power. At 16k btu it's rated at 960w and 9A. Most DC Air units (over maybe 4k btu) are usually just 110v units with a built in inverter. I do believe there is a 24v unit, but if you don't have 24v that's another issue to deal with.
I just got one, (i16) and haven't got it installed yet, but it is a nice piece of equipment.
If you want to see a service manual (Not a marketing brochure) send me a PM and I'll forward a copy to you.
I have 700 AHr of LiFePo with 750 W of solar and plan on adding another 10k btu unit, that will run as low as 3K btu to my aft cabin to run off of the batteries for a few hours.
Dwain

[a64pilot]

Originally Posted by LoudMusic

I run a 12000 BTU Dometic from 120v on battery that is charged from solar during the day.

You'll need an inverter that can sustain that amount of power output without risking failure. At this time I have an older Magnum 2812. It runs at about 50% load when running the aircon along with other boat services.

You'll also need quite a lot of battery. These airconditioners will consume about 120A when running. I have 1200Ah of lithum at 12v.

And quite a lot of solar to charge it back up during the day. I have 2100w.

I do not have enough battery or solar to feel comfortable running the aircon 24h/day. Primarily solar. I think another 300Ah battery, and probably another 3000w of solar, would be necessary to just leave the aircon on all the time.

We use it to cool down the master cabin for a few hours before bed.

You guys who desire to run AC off of batteries ought to read this post.
Forget the batteries, he’s doing it and predicts that to do it continuously, it would take 5KW of Solar.
If you can’t get close to that much Solar, then you need to think of another way, doing it with less than a Kilowatt is fantasy.
I have a Kilowatt and often in Winter it’s not enough to run my boat, and that with no AC use at all.

[CoryW]

I just purchased the Zero Breeze for my Precision 23 and it works amazing for small spaces. Best part, It works on both my solar and its as a battery pack that allows it to run around 5 hrs.
I also like being able to easily remove it when away from the marina.

https://www.zerobreeze.com/products/zero-breeze-mark-2

[SeeMonstrEd]

If you want to run AC 7/24 you are going to need allot more solar and batteries. I have 1800watts with 980ah battery bank and a 3KW inverter. I can run my 16K AC unit for about 30 minutes before my batteries start dropping. You are also going to need major cables to the inverter to carry enough current. I have dual 4/0 to the inverter to keep them from over heating.

My AC unit pulls about 13a if you include the raw pump. It is a newer MarinaAire 16K BTU. It does not have the soft-start installed but I probably will be adding that.

Note: most AC units do not include the water pump">raw water pump in the specs but it won't run without it. Most raw water pumps pull about 2a. I recommend the March Pumps like LC-3CP-MD. The others I have tried died very quickly. The March Pumps are fully submersible and liquid cooled. I am in the tropics and run the AC 7/24 on the shore power. At anchor I run it long enough to cool off the cabin before bed.

[jmschmidt]

Maybe not possible? It isn't with my 12 panel, 3KW battery storage solar system on my house which runs a 48" Sub Zero, a separate freezer, a beer cool (most important), one computer, one TV and a few lights.

The capacitor start on just single AC unit gets all screwed up and the machine starts chugging and groaning when trying to get up to speed. Can't be good for the machine. Maybe something small 2000BTU would run OK?

[chasfgr]

Rather like the question, "how can I contact my fairy godmother?"

[sailingchiro]

A person can purchase alot of fuel for a generator for the amount it would take to use solar for a/c or propulsion.
I am estimating $40k-50k. We can ask the guy with 32kwh of lifepo4 how his system is working.

My genset burns 2 gallons per night for a/c. And that is for 10 hours of a/c. I am adding bigger fuel tanks. My genset makes less noise than my a/c pump.
I have 800watts of solar and 7kwh lifepo4 for solar/battery at 24 volts for refrigeration and charging 12 volt house bank.

FYI Running a higher voltage solar/battery bank reduces the current loads and wire diameter. My house is 12 volts but have 24 volts from solar on a seperate system.
My opinion, if I were to run a solar/battery system for a/c, it would be at the least a 48 volt system.

[NaClyDog]

Originally Posted by sailingchiro

A person can purchase alot of fuel for a generator for the amount it would take to use solar for a/c or propulsion.
I am estimating $40k-50k. We can ask the guy with 32kwh of lifepo4 how his system is working.

My genset burns 2 gallons per night for a/c. And that is for 10 hours of a/c. I am adding bigger fuel tanks. My genset makes less noise than my a/c pump.
I have 800watts of solar and 7kwh lifepo4 for solar/battery at 24 volts for refrigeration and charging 12 volt house bank.

FYI Running a higher voltage solar/battery bank reduces the current loads and wire diameter. My house is 12 volts but have 24 volts from solar on a seperate system.
My opinion, if I were to run a solar/battery system for a/c, it would be at the least a 48 volt system.

With solar and a hydrogenerator, you can go a long way to not needing to burn so much fuel only to burn more fuel to lug around more fuel. I'm thinking bluewater cruisers who want the ability to go to remote places where fuel isn't so readily available.

[sailingchiro]

Originally Posted by NaClyDog

With solar and a hydrogenerator, you can go a long way to not needing to burn so much fuel only to burn more fuel to lug around more fuel. I'm thinking bluewater cruisers who want the ability to go to remote places where fuel isn't so readily available.

That is if I use a/c. We only use a/c on hot windless bug filled nights. Which is very infrequent. I prefer sleeping on the tramp in a mosquito net. Sorry, but hydrogenerators and solar are not going to produce enough energy to run a/c without huge expenses. If you are using a hydrogenerator, then you have wind because you are sailing, don't need A/C. Blue water sailors don't use a/c. We spend roughly $7000 in folding props in order to reduce drag on our boats. The last thing I want to throw out to slow me down is a hydrogenerator. maybe a wind generator but the noise. My solar/lifepo4 is for refrigeration. Yes, remote places requires us to store more fuel. Hence bigger fuel tanks. Which also runs my water maker, which is 1/2 gallon per week. The point isn't the fuel/solar/hydrogenerator/Lifepo4, it is the need for a/c 24/7. Most people will acclimate to warmer climates in just 3-5 days.

[Enyar]

Originally Posted by sailingchiro

A person can purchase alot of fuel for a generator for the amount it would take to use solar for a/c or propulsion.
I am estimating $40k-50k. We can ask the guy with 32kwh of lifepo4 how his system is working.

My genset burns 2 gallons per night for a/c. And that is for 10 hours of a/c. I am adding bigger fuel tanks. My genset makes less noise than my a/c pump.
I have 800watts of solar and 7kwh lifepo4 for solar/battery at 24 volts for refrigeration and charging 12 volt house bank.

FYI Running a higher voltage solar/battery bank reduces the current loads and wire diameter. My house is 12 volts but have 24 volts from solar on a seperate system.
My opinion, if I were to run a solar/battery system for a/c, it would be at the least a 48 volt system.

48v and an inverter? Why not run a 12v or 24v DC aircon?

[SailingHarmonie]

Originally Posted by markguthrie

I starting on the process of putting in a solar system so that I can be on the hook and run the AC for one stateroom overnight without running my geny.

I will be buying a new AC just for this. Any input? My contractor is recommending this one. Velair 16k BTU, 110v. I have gotten input that I should get a DC. I have 12V.

Mark
St. Pete FL
Navigator '53 stink pot

It seems everybody talks generalities, and nobody talks NUMBERS, so let's do that. We'll assume your HVAC guy is on the ball, and has your unit sized correctly.

I am running a 13K BTU unit that consumes 1200 W when running including fan and pump. So your unit will consume roughly 16/13*1200 = 1500 W. Let's assume that "overnight" consists of about 10 hours, and without sun beating down, you will hopefully be running something like a 50% duty cycle.

So... let's calculate again...
10 * 1500 * 50% = 7500 W-hr

I have 630 Watts of solar panels installed that experience almost no shading. They generate (at best!) 3500 W-hours of power a day. So to start with, assuming that the solar is ONLY used to power your AC, you need:

7500 / (3500 / 630) = 1350 Watts of solar and a nice fully sunny day, which is actually kind of rare in the tropics...

Now... you need some batteries to put all that power into.

Again, lets assume that this battery bank is ONLY used for your AC power. I know that is unrealistic, but it will give you an idea how much you have to add to what you have currently.

7500 W-hrs ~ 625 Amp-hours @12 Volts. Assuming you do not want to draw down more than 40 % of the batteries capacity in one night of air conditioning, that is a battery bank of 1560 Amp-hrs. That's a LOT...

These are really, really rough calculations. I have made a lot of assumptions and simplified things a lot. But they will give you are really good idea of what you are up against. Working a much sharper pencil on these calculations will not make the numbers easier to achieve.

[Chuck34]

Originally Posted by Enyar

48v and an inverter? Why not run a 12v or 24v DC aircon?

3 year old thread. I’m guessing the OP has already done something

[The Yacht Rigger]

Originally Posted by SailingHarmonie

It seems everybody talks generalities, and nobody talks NUMBERS, so let's do that. We'll assume your HVAC guy is on the ball, and has your unit sized correctly.

I am running a 13K BTU unit that consumes 1200 W when running including fan and pump. So your unit will consume roughly 16/13*1200 = 1500 W. Let's assume that "overnight" consists of about 10 hours, and without sun beating down, you will hopefully be running something like a 50% duty cycle.

So... let's calculate again...
10 * 1500 * 50% = 7500 W-hr

I have 630 Watts of solar panels installed that experience almost no shading. They generate (at best!) 3500 W-hours of power a day. So to start with, assuming that the solar is ONLY used to power your AC, you need:

7500 / (3500 / 630) = 1350 Watts of solar and a nice fully sunny day, which is actually kind of rare in the tropics...

Now... you need some batteries to put all that power into.

Again, lets assume that this battery bank is ONLY used for your AC power. I know that is unrealistic, but it will give you an idea how much you have to add to what you have currently.

7500 W-hrs ~ 625 Amp-hours @12 Volts. Assuming you do not want to draw down more than 40 % of the batteries capacity in one night of air conditioning, that is a battery bank of 1560 Amp-hrs. That's a LOT...

These are really, really rough calculations. I have made a lot of assumptions and simplified things a lot. But they will give you are really good idea of what you are up against. Working a much sharper pencil on these calculations will not make the numbers easier to achieve.

Keep in mind, this person has LifeP04 batteries, so discharge can be as much as 80% with zero concerns, apart from recharging.