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  • #16
    Originally posted by Sunking View Post
    To optimistic and flawed logic. With a battery system you cannot use yearly average insolation. You have to use worse case of the shortest months in the year. If you use 5 hours, and your December insolation is 3 hours, welcome to being dark most of winter with dead batteries that need replaced.
    How much air conditioning do you expect him to be using in December?

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    • #17
      Originally posted by Bucho View Post
      How much air conditioning do you expect him to be using in December?
      Maybe it is a heat pump A/C and so is being used at full capacity in the winter too?
      SunnyBoy 3000 US, 18 BP Solar 175B panels.

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      • #18
        Originally posted by inetdog View Post
        Maybe it is a heat pump A/C and so is being used at full capacity in the winter too?
        I suppose if he doesn't have insulation or gets record low temps that could happen.

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        • #19
          Real world example

          I run reverse cycle split system air conditioning off grid in 48°C summer heat.
          Lessons learnt:
          Install most efficient unit available. A/C only a small room for shelter from extreme heat.
          If sufficient PV watt input and high temperature, set to a/c for 27°C.
          If low PV input, set to dehumidify only cycle to aid comfort. Uses ~1/3 of full a/c power.
          If sufficient PV watt input and medium temperature when set to dehumidify only, can service double the area (open door into house). Good instrumentation helps manage a/c use: PV watts input, battery voltage, SOC and AC watts used.

          A/C is 240VAC RC Inverter so soft start load and continuously variable compressor rather than simple all on/all off cycle.
          Model is Mitsubishi Heavy Industries SRC25ZIX-S, rated 2.55Kw/3.0Kw and is awesomely efficient.
          Cooling EER 5.21, heating COP 5.26 means: cooling 480W in, 2.55Kw out, heating 570W in, 3.00kW out.
          Only the slightly smaller 2.0Kw beats it with EER 5.71 and COP 5.52.

          The smaller systems are key! These small 2.0 and 2.5kW units are extremely efficient and most solar friendly.
          In larger 3.5Kw and 5kW systems the efficiency plummets 40% to EER of only 4 and 3.5, average for good split systems. DONT EVEN THINK OF BIG SYSTEMS FOR OFF GRID! Better to install two smaller units servicing different areas rather than one big system! Cheaper than extra panels/charge controller/batteries.
          We air con just one well insulated room 23m^2 (250 sq.ft) easily with 18°C difference (45->27) using about 600W from 2KW array and can a/c until 10pm adjusting temperature up to 30°C. We do not a/c overnight but might set the cycle to dehumidify only for a few hours.

          In shoulder seasons on chilly mornings, we turn on reverse cycle to heat the small room. Lessens the wood fire hassle.
          Note with clear weather the clear night sky means chilly morning but lots of PV during day, so run a/c for 45mins in morning. Cloudy weather means less night time temperature drop and not much PV next day, so don't need to run a/c in morning.

          There is a lot more to be said on this topic....

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          • #20
            Below is a cut and paste from a website. Do you guys think it is possible?


            For years we have been saying that solar powered air conditioning just makes sense- if you are boiling in Phoenix the sun is probably shining really hard. We have seen big units, evaporative units that won't work in humid climates, a few vaporware units and even home-made absorption chillers

            Now it looks like a Spanish company, Rotartica, has put it all together, by combining evacuated tube thermal collectors with a water-heated absorption chiller, and sized it at 4.5Kw (1.28 tons) for residential use, all packaged in a neat little box.

            From an operation point of view it is very simple: you put hot water in, you get cold water out, which you can run to a conventional fancoil. The hot water in can come from any source, but evacuated tube collectors, which used to be very expensive, are pretty affordable now. If you want to get more techie:

            In an absorption chiller unit the evaporator and condenser are the same as in conventional systems but the function of the compressor is performed by a chemical absorbent (LiBr) and a
            heat generator, with only a pump being required to provide the change in pressure. As there is
            no compressor, electricity consumption is reduced significantly.



            The diagram is a graphic representation of the Single Effect Absorption Cycle, which
            functions as follows:

            1. The refrigerant, together with the salt or absorbent in the Generator, evaporates due
            to the heat provided by a burner or an external circuit leading to a heat exchanger.

            2. The absorbent is conveyed to the Absorber as a solution with a low refrigerant content,
            while the refrigerant that has evaporated in the Generator travels to the Condenser
            where it is condensed and releases heat.

            3. Due to the difference in pressure, the refrigerant flows to the Evaporator where, at a
            low temperature and as a result of the low pressure, it evaporates and absorbs heat
            from the circuit which subsequently goes on to cool the room.

            4. Lastly, the evaporated refrigerant is attracted by the absorbent in the Absorber, where
            the refrigerant-rich absorbent solution is created once more and is conveyed to the Generator where the whole cycle begins again.



            We don't know the price, (probably expensive) but operating costs will be negligible and it runs when the sun is hottest and electricity the most in demand; once those smart meters become common this may be the only way to affordably cool on the hottest days. If you are worried about being cool at night, perhaps you can add an ice bear.

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            • #21
              Originally posted by louiedonovan55 View Post
              Hello, I have this question, Is there such an air conditioning system that can be powered by solar energy? Air conditioner such as the split system like those small units.

              May be you can buy portable Air Conditioner which do not support high Voltage, Make sure you check your Room area for better idea. Or Contact with Professional "Air conditioner repair company in phoenix" for better understanding

              Regards

              Mod Note. Please do not attach advertisement links to companies without first getting permission from the Admin of this Forum.
              Last edited by SunEagle; 09-09-2015, 11:23 AM. Reason: deleted advertisement link

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              • #22
                You need ice at night for the AC? That doesn't help capacity in an off-grid situation as you have to burn more Watts to freeze the water than you'll recover.
                1150W, Midnite Classic 200, Cotek PSW, 8 T-605s

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                • #23
                  Who in the Hell digs these old dead threads up? You are talking to ghost and the OP has not been here for a year.
                  MSEE, PE

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