Announcement

Collapse
No announcement yet.

Running 5000 BTU air conditioner solar

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Running 5000 BTU air conditioner solar

    Hello everyone. I've been doing a lot of research on solar I have a small 75 watt set up now but I'm just a newbie. I'm going to be going off grid and I'm trying to figure out how to run a 5000 BTU air conditioner. I was hoping someone would be so generous to help me figure out what kind of system I would need to do that. Can you run 5000 BTU AC on a 12 volt battery Bank? From my research they run at 5 amps. I'm not sure what the surge is. What size power inverter would I need?

    I want this setup to be specific just for the AC and nothing else.
    So I may be way off but I was thinking even if it ran 24 hours a day that would be around 120 amp hours.

    Please advise would 4 to 6 Trojan t105 baterry at 12 volt ,450 to 675 amps and 3 to 4 panels 250 watt should handle it? I don't trust my solar math yet hoping someone with some knowledge and experience can help me have an idea so I can estimate price and other factors. I am in Florida so plenty of Sun.

  • #2
    First all your math is dead wrong. The Window Shaker may pull 5 amps, but that is at 120 Volts AC. At 12 volts taking Inverter efficiency into consideration would pull 65 amps. So to run at 12 volts 24 hours per day would require 65 amps x 24 hours x 5 days = 7800 AH or a 6000 pound $11,000 battery you replace every few years. To charge a battery the size of your living room is going to require. 6000 watt solar panel, and 6 very expensive 80 Amp Charge controllers, and a 6000 pound battery. .

    So it is easy to see this is never going to happen and you would be a damn fool to try. Just remember this. Anything you take off grid is going to cost you 5 to 10 times more than buying the power from the POCO. Not only will it cost you a fortune, but also makes you a very heavy polluter. Forget about it.
    MSEE, PE

    Comment


    • #3
      Find your needed watt hours in the chart below
      Case Battery style est co$t Volt Ah Wh each Qty in Series Bank V Total Wh Useable 50% 3 day Res. Allowed daily drain est total co$t cost/wh Cells to check levels Interconnects required @ $8 ea Weight ea
      24 "Marine" flooded $ 95.00 12 90 1080 1 12 1080 540 270 $ 95.00 $ 0.09 6 0 ~70
      24 "Marine" flooded $ 95.00 12 90 1080 2 24 2160 1080 540 $ 190.00 $ 0.09 12 1 ~70
      24 "Marine" flooded $ 95.00 12 90 1080 4 48 4320 2160 1080 $ 380.00 $ 0.09 24 3 ~70
      GC2 Golf cart, flooded $ 95.00 6 190 1140 2 12 2280 1140 570 $ 190.00 $ 0.08 6 1 ~70
      GC2 Golf cart, flooded $ 95.00 6 190 1140 4 24 4560 2280 1140 $ 380.00 $ 0.08 12 3 ~70
      GC2 Golf cart, flooded $ 95.00 6 190 1140 8 48 9120 4560 2280 $ 760.00 $ 0.08 24 7 ~70
      31 AGM, Carbon Foam $ 400.00 12 116 1392 1 12 1392 696 348 $ 400.00 $ 0.29 0 0 ~90
      31 AGM, Carbon Foam $ 400.00 12 116 1392 2 24 2784 1392 696 $ 800.00 $ 0.29 0 1 ~90
      31 AGM, Carbon Foam $ 400.00 12 116 1392 4 48 5568 2784 1392 $ 1,600.00 $ 0.29 0 3 ~90
      aa Rolls "L-16" $ 861.00 6 546 3276 2 12 6552 3276 1638 $ 1,722.00 $ 0.26 6 1 221
      aa Rolls "L-16" $ 861.00 6 546 3276 4 24 13104 6552 3276 $ 3,444.00 $ 0.26 12 3 221
      aa Rolls "L-16" $ 861.00 6 546 3276 8 48 26208 13104 6552 $ 6,888.00 $ 0.26 24 7 221
      Trojan L16 Floor sweeper $ 225.00 6 380 2280 2 12 4560 2280 1140 $ 450.00 $ 0.10 6 1 115
      Trojan L16 Floor sweeper $ 225.00 6 380 2280 4 24 9120 4560 2280 $ 900.00 $ 0.10 12 3 115
      Trojan L16 Floor sweeper $ 225.00 6 380 2280 8 48 18240 9120 4560 $ 1,800.00 $ 0.10 24 7 115
      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

      solar: http://tinyurl.com/LMR-Solar
      gen: http://tinyurl.com/LMR-Lister

      Comment


      • #4
        Thanks sun-king for the knowledge. I warned you I was a newbie and probably off with the math. I have a much better understanding now. Definitely open my eyes a little.

        ​​​ I think could do it if I didn't run AC at night and have six 250 watt panels. That's crazy. But tell me if this makes sense. The AC is 500w. If I run it for 12 hours that's 6000 w of energy use. If I have a 1500 panel times 4 hours is 6000 so I would still be full battery. Or is my Math way off again?

        Comment


        • #5
          Originally posted by Keith Mo 200 View Post
          Thanks sun-king for the knowledge. I warned you I was a newbie and probably off with the math. I have a much better understanding now. Definitely open my eyes a little.

          ​​​ I think could do it if I didn't run AC at night and have six 250 watt panels. That's crazy. But tell me if this makes sense. The AC is 500w. If I run it for 12 hours that's 6000 w of energy use. If I have a 1500 panel times 4 hours is 6000 so I would still be full battery. Or is my Math way off again?
          No that is 6000 watt hours, not watts.

          Watt Hours = Watts x Hours.

          500 watts x 12 hours = 6000 watt hours.

          Do not know where you live, but if you live in the south and lucky will get 5 Sun Hours. To use 6000 watt hours in a day, requires the panels to generate 9000 watt hours. So with a 5 Sun Hour Day Panel Wattage = 9000 wh / 5 sun hours = 1800 watts of panels, 2000 to be safe.

          That automatically makes it a minimum 24 volt battery system which is still foolish. If you were to do this would use a 48 volt battery system. Economics demand 48 volts. As for the battery no matter what battery voltage you choose is still a 25,000 to 30,000 watt hour capacity battery weighing 1600+ pounds and costing over $4000 every few years. At 48 volts will require a 550 AH battery like 8 of these Rolls 6-CS17P, 6-volt 560 AH batteries. They weigh 221 pounds x 8 units @ $850 each.

          Sorry to beat up on you, but I suspect you do not know what you are asking for. Do you have $7000 to $9000 to make that window shaker shake money out of your pockets? Or just pay the POCO a dollar a day for their pockets? Either way you loose, how bad do you want it to hurt? A little or a lot?
          Last edited by Sunking; 08-08-2018, 05:48 PM.
          MSEE, PE

          Comment


          • #6
            Originally posted by Keith Mo 200 View Post
            Hello everyone. I've been doing a lot of research on solar I have a small 75 watt set up now but I'm just a newbie. I'm going to be going off grid and I'm trying to figure out how to run a 5000 BTU air conditioner. I was hoping someone would be so generous to help me figure out what kind of system I would need to do that. Can you run 5000 BTU AC on a 12 volt battery Bank?
            Yes, although it's not recommended due to the surge power you will need to start it.
            From my research they run at 5 amps. I'm not sure what the surge is. What size power inverter would I need?
            Generally a 2000 watt inverter is safe (since that's what a 120VAC A/C can draw continuously.) You could probably live with a 1000 watt inverter that will surge to 2000 watts, but it's not guaranteed.
            I want this setup to be specific just for the AC and nothing else.
            So I may be way off but I was thinking even if it ran 24 hours a day that would be around 120 amp hours.
            1200 amp hours of battery. 5 amps at 120 volts is 50 amps at 12 volts. Actually closer to 2400 amp hours because you don't want to draw it down more than 50%. So you are looking at about $8K in batteries. Probably $10K or so for the whole system.
            Please advise would 4 to 6 Trojan t105 baterry at 12 volt ,450 to 675 amps and 3 to 4 panels 250 watt should handle it? I don't trust my solar math yet hoping someone with some knowledge and experience can help me have an idea so I can estimate price and other factors. I am in Florida so plenty of Sun.
            Ha! No.

            If you want to run your A/C off solar you have a few reasonable options:

            1) Get a grid tie system sized to give you about 14kwhr a day. (cheapest option)
            2) Get a smaller grid tie system and do something clever to reduce the A/C's cooling when solar is not available. (LG now has an inverter based window A/C that would work for this; you can reduce the power gradually as sunlight decreases.)

            If you absolutely must use batteries, get a big solar array (1000 watts or so) a smallish 12V AGM battery and a 2000 watt inverter. Then only turn on the A/C when the sun is shining.

            Comment


            • #7
              Thanks guys for sharing the info. Much spend very disappointing. Looks like my only option would be running it when the sun is shining LOL. I can't be shaking money out of my pockets!

              Comment


              • #8


                "If you absolutely must use batteries, get a big solar array (1000 watts or so) a smallish 12V AGM battery and a 2000 watt inverter. Then only turn on the A/C when the sun is shining."
                [/QUOTE]


                jflorey thanks for the idea. Will this destroy the battery from running such a big load off of it? Can I still get the full life expectancy?

                Comment


                • #9
                  And when do you say small 12-volt AGM ? like a 100 ahour?

                  Comment


                  • #10
                    Originally posted by Keith Mo 200 View Post
                    jflorey thanks for the idea. Will this destroy the battery from running such a big load off of it? Can I still get the full life expectancy?
                    It will definitely shorten the life of the battery, but you're not using the battery for energy storage, so it doesn't matter as much. You are just using it to store enough energy to start the compressor. All the run power comes from the solar array.

                    AGM's can charge/discharge at around C/4. So you do the math. 1000 watts gives you 83 amps at 12V, so you'd need (83*4)= 330 amp-hours. Two DC400-6's would work.

                    Comment


                    • #11
                      Keith Mo:

                      You seem to among the myriad who show up here, more than a few after the damage has been done, who jump on a germ of an idea planted by some peddler or the green wash media without knowing what's involved, either from the standpoint of what's required, what's available, what all of it will cost and how practical or impractical it may be.

                      Stay on the grid until you've fully researched the idea. You'll learn as much, if not more about what's needed for a lot less toil, treasure and wasted effort. Experiment is fun and makes a nice hobby, but don't expect what you have in mind to be in any sense practical.

                      Comment


                      • #12
                        Originally posted by Keith Mo 200 View Post

                        "If you absolutely must use batteries, get a big solar array (1000 watts or so) a smallish 12V AGM battery and a 2000 watt inverter. Then only turn on the A/C when the sun is shining."

                        jflorey thanks for the idea. Will this destroy the battery from running such a big load off of it? Can I still get the full life expectancy?
                        [/QUOTE]First partly cloudy day and you are toast.

                        MSEE, PE

                        Comment


                        • #13
                          Sunking. I understand this. Why so aggressive and negative. It's like you want me to fail. I never claimed to know what I'm talking about that's why I'm here to learn. I realize now what it takes to run something like even a tiny 5000 BTU isn't feasible. One big thing I learned from you is amp change from 120 volt and 12 volt. Don't know how I missed that just learning so much so quickly some things are bound to go in one ear and out the other. The 75 watt panel that I have I actually made myself soldered each cell together encapsulated it with film and heat gun. Was a fun project.

                          jflorey thanks again for the positive feedback and actually trying to give me an option of what is possible.
                          Last edited by Keith Mo 200; 08-09-2018, 06:19 PM.

                          Comment


                          • #14
                            Originally posted by J.P.M. View Post
                            Keith Mo:

                            You seem to among the myriad who show up here, more than a few after the damage has been done, who jump on a germ of an idea planted by some peddler or the green wash media without knowing what's involved, either from the standpoint of what's required, what's available, what all of it will cost and how practical or impractical it may be.

                            Stay on the grid until you've fully researched the idea. You'll learn as much, if not more about what's needed for a lot less toil, treasure and wasted effort. Experiment is fun and makes a nice hobby, but don't expect what you have in mind to be in any sense practical.
                            Thank you for the advice .
                            I have an acre in Northern Florida. I've always plan to eventually move there . There is no grid to tie two. Other big problem is there water either. Wells are expensive 2. So that's exactly what I'm doing fully researching trying to learn as much as I can and knowing what is actually possible for practical and what is not. Especially with a low budget. Yes it is fun I have made a 75 watt panel soldering each cell together. Was a fun project.

                            Comment


                            • #15
                              Let me suggest something else. Forget your highly inefficient window shaker, which wants you to convert
                              DC to battery to AC. There are now mini split HEAT PUMPS (Mitsubishi, model ACDC12C) that are FAR
                              more efficient and will run DIRECTLY off your solar panels. They won't run without good sun, but then
                              you don't need air. Can do some heating too. Bruce Roe

                              Comment

                              Working...
                              X