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  • Solar to run a fridge.

    hello all.

    I bought 3 - 110 watt solar panels, mounted them on top of a 20' hydro pole in lots of sunlight (no tracker), then I found out that both the solar panels and the small 300 watt grid intertie inverter that I bought - I cannot use. Since they are not CSA certified, or do not have ANY Canadian content, I am not allowed to hook them to the grid (or my house) here in Ontario Canada.
    I did find out, that I can set up a stand alone power system with batteries to run off grid. I already have a 20 amp morningstar charge controller now I would like to get a battery bank, inverter and battery state of charge meter.
    I hope that when all is said and done, I will be able to run my fridge off of this system. I purchase a brand new fridge - don't have the square footage with me here - and then wrapped it in 2 inches of white styrofaom - front - back - sides and top. Using a Kill-o-watt meter, without the foam, it used about 1.6 killowatts over 24 hours, with the foam it uses .65 of a killowatt hour a day - 650 watts day ? That is from 11 pm to 11 pm, according to the meter...
    Using the meter, the fridge draws 700 watts for a few seconds at start up (start up surge), and I do have a 700 watt square wave inverter, but I am worried about heating up and frying the fridge motor using this type of inverter. . .
    I would like to just start firing all the usual questions at you guys, but I think I will take some time to read the forums, as there is ALOT of info here.

    Thats it so far.
    3 -110W-12 V solar/wired 36 V. - midnight-monitor. - Morningstar mppt-15 - Samlex 1,000watt/24V inv. - 200 AH batteries (so far)
    3 ton GSHP. - Tempra ODWH.- Apricus high eff. water heater - 420 Gallon rain water system for laundry. 6" Rocket Mass Heater with 10' bed for workshop heat. - 2.1 KW - net metered solar (in process)

  • #2

    Re: Solar to run a fridge.

    Re: Solar to run a fridge.

    Welcome to the forum.

    First some terminology; your refrigerator is using 650 Watt hours per day, not just Watts. That is about half normal. A caution about covering it with insulation; over time this could backfire as you may be covering the areas that radiate heat. You can check this by simply putting your hand on the surface when it's running and see if it gets warm.

    You are right that the 'frige will have quite a start-up surge. It is doubtful that a 700 Watt inverter will handle it, especially an MSW type. You are also right that the 'frige will not like MSW; although it would work it will not work well.

    You have three 110 Watt panels or 330 Watts total. Over the course of a day you could expect 686 Watt hours AC from them; just enough to run the refrigerator (based on good insolation and 4 hours of equivalent good sun). That's also just enough panel for a couple of 220 Amp hour 6 Volt batteries in series which would also just provide the power necessary to run the 'frige. The panels are probably about 6 Imp, so the MS 20 Amp controller should do.

    It is possible for this to work, but it's a bit on the edge. When you add the power consumption of the inverter necessary to run the refrigerator you may not have enough power.

    Comment


    • #3

      Re: Solar to run a fridge.

      Re: Solar to run a fridge.

      to add to your standalone system to make it operational it may cost as much as buying new pvs and throwing small gt inverters on them, all certified.

      i know you don't want to have what you already bought to be useless to you so you could use it for lights being they aren't as critical of the modsine inverter. the batteries will need to be sized for your loads no matter what loads you opt for. keep in mind that you don't want to draw off more than 50% of the battery capacity over 24hrs to preserve battery life. they aren't meant to be drained dead.
      NIEL

      Comment


      • #4

        Re: Solar to run a fridge.

        Re: Solar to run a fridge.

        Further to Carriboocoot's note on totally insulating all sides of the fridge - - - where does your fridge get rid of the heat it extracts from within? Many have coils just under the outer metal skin that do that, others have separate "coils" mounted on the outside of the back. The former will not operate properly if it can't get rid of the extracted heat, the latter will work fine IF you put the insulation under those external coils, between the coils and the actual cabinet.
        1900 watts PV, (1000 watts PV feeding MidNite Classic 150; 900 watts PV + 160 watts micro hydro both feeding into a single shared Morningstar TS-MPPT-60) ; Xantrex Pure Sine 1800/12 for heavy loads; Xantrex Pure Sine 1000/12 on 24/7 for everything else; six Rolls Surrette 2 volt L16 @ 12 volts.
        Domestic hot water totally provided by the sun 8 months out of every year via thermal panel.

        Comment


        • #5

          Re: Solar to run a fridge.

          Re: Solar to run a fridge.

          Originally posted by waynefromnscanada View Post
          Further to Carriboocoot's note on totally insulating all sides of the fridge - - - where does your fridge get rid of the heat it extracts from within? Many have coils just under the outer metal skin that do that, others have separate "coils" mounted on the outside of the back. The former will not operate properly if it can't get rid of the extracted heat, the latter will work fine IF you put the insulation under those external coils, between the coils and the actual cabinet.
          Wrong. Freezers have the coils wrapped under the skin. Refrigerators do not.
          24V system. 8x BPSX170 and 4x Suntech 170 on Redrok trackers through Midnite Classic200. 250W of fixed homebrew panels though C40. DanB 10' Piggot axial style wind turbine through Classic 150 and Ryan-copied clipper. HuP Solar One, 845Ahr@24V Outback VFX3524. Generac 7550EXL.

          Comment


          • #6

            Re: Solar to run a fridge.

            Re: Solar to run a fridge.

            Originally posted by Volvo Farmer View Post
            Wrong. Freezers have the coils wrapped under the skin. Refrigerators do not.
            Not so fast. I had a Sanyo fridge with the coils under the skin, and a local organization I belong to, has a Maytag fridge with under-skin coils, I know because I moved it by myself to another room this past Saturday. And three feet from me at this very moment, I have a Sears upright freezer which I use as a fridge, and it has external coils. I also used to sell fridges that had neither. They used a fan cooled condenser down under, beside the compressor. So it depends on the design the manufacturers decide to use.
            1900 watts PV, (1000 watts PV feeding MidNite Classic 150; 900 watts PV + 160 watts micro hydro both feeding into a single shared Morningstar TS-MPPT-60) ; Xantrex Pure Sine 1800/12 for heavy loads; Xantrex Pure Sine 1000/12 on 24/7 for everything else; six Rolls Surrette 2 volt L16 @ 12 volts.
            Domestic hot water totally provided by the sun 8 months out of every year via thermal panel.

            Comment


            • #7

              Re: Solar to run a fridge.

              Re: Solar to run a fridge.

              Sorry about my trite response, my original post did not go through. You are correct. However 95% of USA domestic refrigerator freezer combos have the coils underneath and are fan cooled. I would be curious to get a model number of that Maytag, because I have never seen one that was not static air cooled from the back or fan cooled from underneath. Almost every USA sold freezer built in the last 15 years, either upright or chest has the coils under the skin like you describe. My understanding was that the OP had a brand new refrigerator/freezer combo, and I have never seen that configuration with the coils wrapped under the skin. I have been repairing appliances for twenty years now and have seen a lot of refrigerators, but I'm always interested in learning something new.
              24V system. 8x BPSX170 and 4x Suntech 170 on Redrok trackers through Midnite Classic200. 250W of fixed homebrew panels though C40. DanB 10' Piggot axial style wind turbine through Classic 150 and Ryan-copied clipper. HuP Solar One, 845Ahr@24V Outback VFX3524. Generac 7550EXL.

              Comment


              • #8

                Re: Solar to run a fridge.

                Re: Solar to run a fridge.

                I think I have the same Maytag in my kitchen. It has the freezer on the bottom. The model is MBB1954GEW. And yes the sides get warm when it is cycling in Summer.

                Comment


                • #9

                  Re: Solar to run a fridge.

                  Re: Solar to run a fridge.

                  Originally posted by Volvo Farmer View Post
                  Wrong. Freezers have the coils wrapped under the skin. Refrigerators do not.
                  My almost new Maytag refrigerator has the coils under the skin.
                  Northern Arizona Wind & Sun Forum & Website Administrator

                  Comment


                  • #10

                    Re: Solar to run a fridge.

                    Re: Solar to run a fridge.

                    I have a kenmore 5.5 cubic foot chest freezer. It has a grill on its side and vents hot air through the grill. I am in the process of adding insulation. It was quite noticible that by laying a piece of 4" iso board foam on the top cover that when I removed the foam, the top cover was a lot colder. I have also done this with the sides and noticed the same effect so I guess it depends on the design.

                    I think in the "old days" the manufactureres were cheap on the insulation so the cases would be cold enough to condense vapor int he air leading to puddling, by putting the coils in the outer layer of the case it kept it warm so water didnt condense. Generally old freezers were energy hogs.

                    Comment


                    • #11

                      Re: Solar to run a fridge.

                      Re: Solar to run a fridge.

                      Originally posted by Cariboocoot View Post
                      I think I have the same Maytag in my kitchen. It has the freezer on the bottom. The model is MBB1954GEW. And yes the sides get warm when it is cycling in Summer.
                      Okay, I looked up that model number. Your refrigerator has 90% of it's condenser coil folded underneath the unit, and it is fan cooled. The other 10% is what we refer to as a "yoder loop". It is a coil of the condenser coil tubing buried under the skin and foamed in, right behind the door gaskets on the body of the refrigerator. The purpose is to keep the doors warm enough to prevent sweating in humid environments.

                      The OP stated he had added foam to the sides and top and back of the refrigerator. This does not affect the yoder loop so much because it gives up most of its heat around the door openings and 90% of the condenser cooling is done underneath the unit by means of the condenser fan. You might feel a little heat on the outside of the refrigerator, but it is inconsequential to the total amount of heat which is dissipated underneath, where the majority of the coil lives.

                      http://www.searspartsdirect.com/part...&prst=&shdMod=

                      That #19 is your condenser coil.



                      If the administrator of this forum would give me his model number, I could look it up as well.
                      24V system. 8x BPSX170 and 4x Suntech 170 on Redrok trackers through Midnite Classic200. 250W of fixed homebrew panels though C40. DanB 10' Piggot axial style wind turbine through Classic 150 and Ryan-copied clipper. HuP Solar One, 845Ahr@24V Outback VFX3524. Generac 7550EXL.

                      Comment


                      • #12

                        Re: Solar to run a fridge.

                        Re: Solar to run a fridge.

                        The point well-made is that you need to know where the coils are before you start covering everything with foam.

                        It was easier in the old days because you could see them: that big white cylinder on top of the ice box!

                        Comment


                        • #13

                          Re: Solar to run a fridge.

                          Re: Solar to run a fridge.

                          I did not include all relevant information again, sorry.

                          My refridgerator has back of the set coils, I made up 4 metal brackets, and extended the "stand offs" that came with the fridge by another 2 inches. Then wrapped it everywhere but the bottom. . . Yes, I did try this with my small chest freezer, and it did work on the lid, but the sides of the unit did get warm when it was running, so I did not even try it on the sides. I agree with you guys on that one, - if the sides of the unit are warm - don't cover it up !

                          Thanks for the info on the RE system. I would LIKE to run the fridge off of these panels, but there are a few other lower power items that I can connect. It would just be nice to have a system to get me started . . . which leads me to the next question, I have a -15 amp- grid powered - 12 V battery charger. Does it change anything having a bigger battery to charge or can I just hook up the charger to the battery posts to charge - or possibly run a seperate "+" and "-" wire outside the battery box ( connected to terminals) to avoid sparks in the battery box ? I am going to get a battery monitor of some kind, so on a low sun day, I would like to charge the battery up with the grid powered charger. . .hopefully not too often. . .

                          I stopped by a local "solar installer" and was told that too run 30 feet (12 V) into the house, I would only need to use 10 gauge wire . . I did not want to argue with an "expert", so I accepted his decision. . . came home and ran it thru the on-line wire size calculator (again) and found a sizing of 6 gauge. . I already called him to see if I can return it or not. . .
                          The other thing is, I am sure that the codes require steel conduit when entering the building envelope, but he sold me pvc conduit. . . which would not meet code if I am right. .
                          Oh, and the morningstar charge controller is not a mpp charger, a buddy is trying to tell me that I will loose something like 30 percent right off the top. . . is it worth getting a mpp charger ?

                          I'll keep you guys updated as I go.
                          3 -110W-12 V solar/wired 36 V. - midnight-monitor. - Morningstar mppt-15 - Samlex 1,000watt/24V inv. - 200 AH batteries (so far)
                          3 ton GSHP. - Tempra ODWH.- Apricus high eff. water heater - 420 Gallon rain water system for laundry. 6" Rocket Mass Heater with 10' bed for workshop heat. - 2.1 KW - net metered solar (in process)

                          Comment


                          • #14

                            Re: Solar to run a fridge.

                            Re: Solar to run a fridge.

                            Originally posted by Skippy View Post
                            Oh, and the morningstar charge controller is not a mpp charger, a buddy is trying to tell me that I will loose something like 30 percent right off the top. . . is it worth getting a mpp charger ?

                            I'll keep you guys updated as I go.
                            Just compare the cost of replacing your PWM charger with an MPPT charger, and then look at how many panels you would have to add to get the same amount of additional power (assuming you have the space) and what they would cost. Decide on that basis.

                            How much you lose will depend on exactly what the Vmp value of your panels is. However, the MPPT controller will also give you a bit more extra power during the winter when the panels are colder. (An interesting calculation because in the winter you need the extra energy more, but 30% of a small amount is still a small amount!)
                            Sunny Boy 3000US, 18 x BP Solar 175b panels, installed 2009.

                            Comment


                            • #15

                              Re: Solar to run a fridge.

                              Re: Solar to run a fridge.

                              Since we have a repair guy here, would it help cool the coils if there was an aditional air space under the fridge? I've heard of retrofitting an aluminum shield between the bottom condenser and the fridge. I'm worried about my soon to be off grid fridge, and anything I can do to help it work better...

                              I honestly thought it had coils under the sides but never felt them get warm, like my friends upright freezer. It would be fine to me to put 2" of blue board around it if it would help.
                              Home system- 20 - 200W Evergreen blems, 2 Classic Lites, E-Panel, 2 Prosine 1800 watt inverters, 800AH 24V forklift Batt, up and running 1 Classic Lite and 14 Suntech 185W in spare room.
                              Experience with Pulse/Trace PC250 Power Center, Original Rouge CC, 80-4/5watt 6v panels, Odds and extras,

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