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  • Refrigerator

    Hi folks, I'm a newbie on this forum.
    I would greatly appreciate some information about a refrigerator. I have an RV, and I just bought a small 4.5 energy efficient refrigerator . I believe its 150 watts and 1.5 amp.

    Please tell me how many watts of 12 v solar do I need for this.... and how many 12 or 6 v batteries? I'm not running anything else on this. It's actually in a cargo trailer, that my RV pulls.
    I cannot thank you enough for the help.

    Doesn't have to be exact.

  • #2
    The first thing that I would do is get a hold of a "kill-a-watt" meter and plug the refrigerator in and measure it's actual power consumption in as close to actual operating conditions as you can.

    When you know how much it actually consumes you can calculate battery, charge controller, battery and panel requirements.

    I switched to an "apartment" refrigerator in my travel trailer and lived in it for a month with the Kill-a-watt connected to get a realistic handle on what my actual power consumption.

    Comment


    • #3
      I agree with PNW_Steve. Knowing the watt or amp rating of a device is still not enough data to know how many daily watt hours it will consume.

      Without that information you would be just guessing the size of the battery / solar pv system.

      Comment


      • #4
        The location of your cargo trailer when in use will make a difference too. If at all possible try to park it in the shade, if available. I'd be curious to see the refer's power consumption in the shade compared to being in the sun all day. Trailers can get pretty warm in the sun. Providing ventilation of some sort would help get the heat from the fridge as well as the sun's heat out.
        2.2kw Suntech mono, Classic 200, NEW Trace SW4024

        Comment


        • #5
          The question that needs to be asked....Is it something that absolutely needs to be kept cold or is it drinks which would be convenient? I run a chest fridge only in the day and have a large mass of liquids to keep it cold at night. I have a large enough array that this system will run even in the rain for days with only a single battery. Opportunity cooling can work 80% of the time with a minimal system.

          Comment


          • #6
            Originally posted by SunEagle View Post
            I agree with PNW_Steve. Knowing the watt or amp rating of a device is still not enough data to know how many daily watt hours it will consume.

            Without that information you would be just guessing the size of the battery / solar pv system.
            I'd be happy with a GUESS!

            Comment


            • #7
              Originally posted by Rubber neck View Post

              I'd be happy with a GUESS!
              Then your guess is as good as mine.
              9 kW solar. Driving EVs since 2012

              Comment


              • #8
                My older energy fridge-freezer uses 1 KWH a day. My new 21 cubic foot freezer seems to be
                a bit less, in part because it is kept in a cool to cold garage. There seems to be a minimum
                amount of energy required for a fridge no matter how small it is. Check yours. Bruce Roe

                Comment


                • #9
                  It depends how long you need the fridge to keep cool for? Will it be 24/7 or just for keeping drinks cold in the daytime?
                  Find the compliance plate which will state its wattage and check that it is 150watts like you said. Refrigerator wattage = 150 Watts
                  Estimated usage = 8 hours per day (just for drink cooling in the daytime)
                  Total energy = 150W x 8h = 1200Wh = 1.2kWh/day

                  Comment


                  • #10
                    To harvest 2kw daily, depends on your sun exposure. A reasonable guess would be 4 hours on a non cloudy day. To get a reliable 500w from array, you need at least 650W of PV, I'd go a bit larger to "be sure". All depends on your budget and acceptance of shutdown in case of cloudy days.
                    That's going to require a 40A controller for 12V system, or a 20A controller for a 24v system.
                    If it were my setup, I'd go with 24V, using 4 golf cart batteries in series (24V 200ah, 4800wh total, 2400wh usable) giving 1 day reserve power
                    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


                    • #11
                      Originally posted by Rubber neck View Post

                      I'd be happy with a GUESS!
                      If I were to guess, I would say: medium.

                      Measure your loads and come up with an "energy budget". From that we can size the system to support your loads.

                      Comment


                      • #12
                        Originally posted by Rubber neck View Post

                        I'd be happy with a GUESS!
                        Ok a worse case would be that 150watts 24 hours per day. That calculates out to 3600watt hours which is probably way too much.

                        You can figure the true value is half that watt hour but even 1800watt hours is a big load to run from a solar/battery system especially at 12V.

                        So as a "guess" I would say using 1800wh a day that would require a 12V battery system rated about 600Ah. (1800wh / 12v / 25% = 600Ah). To charge that battery will require 60amps which calculates out to over 720 watts and a MPPT CC rated 60amps.

                        So that is my guess. Take it for what it is or if you can determine your true daily watt hour usage you can design a system form that.
                        Last edited by SunEagle; 03-15-2020, 12:18 PM.

                        Comment


                        • #13
                          Here's a simple screenshot of a estimator

                          SimpleEstimator.jpg
                          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


                          • #14
                            Originally posted by SunEagle View Post

                            Ok a worse case would be that 150watts 24 hours per day. That calculates out to 3600watt hours which is probably way too much.

                            You can figure the true value is half that watt hour but even 1800watt hours is a big load to run from a solar/battery system especially at 12V.

                            So as a "guess" I would say using 1800wh a day that would require a 12V battery system rated about 600Ah. (1800wh / 12v / 25% = 600Ah). To charge that battery will require 60amps which calculates out to over 720 watts and a MPPT CC rated 60amps.

                            So that is my guess. Take it for what it is or if you can determine your true daily watt hour usage you can design a system form that.
                            Thanks for that. I understand that I need to provide more info on my little 4.5 energy saver fridge
                            Last edited by SunEagle; 03-15-2020, 12:18 PM.

                            Comment


                            • #15
                              Most small dorm size fridges, consume AS MUCH power as a full size energy star fridge - because they have thin insulation and are built cheap.
                              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

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