Announcement

Collapse
No announcement yet.

Automatically switch off aircon when hybrid system goes off grid

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

  • Automatically switch off aircon when hybrid system goes off grid

    I'm planning to install a hybrid solar system in a single-phase building. It has several aircons. As the battery cannot supply the aircons long, they should be turned off automatically in case of switching to battery. Are there a kind of "smart switches" (install one per aircon) that turn off aircon in case battery is active ?

  • #2
    I don't know of a switch but when you install the hybrid inverter swing your critical loads to a separate sub panel. Leave the AirCon on the main panel. My hybrid inverter only supports 60 Amps so I had to separate the heavy loads anyway.
    9 kW solar, 42kWh LFP storage. EV owner since 2012

    Comment


    • #3
      Thanks and this would require separate wires for the aircon which is difficult and expensive. Better would be a "small automatic switch" directly at the aircon that detects it is running on battery now.

      Comment


      • #4
        I agree with Ampster. The OP might be better off moving critical loads to a panel fed by the batteries and make sure the Aircons are not fed by that panel. Otherwise there is no sure way of having a "relay" turn off loads every time.

        You can look for one of those smart relays but it would have to be wired in a way that it can tell the grid is down and the batteries are now providing its power. Not sure how you do that without knowing exactly how your system is wired.

        Comment


        • #5
          Originally posted by dietrichbern View Post
          Thanks and this would require separate wires for the aircon which is difficult and expensive. Better would be a "small automatic switch" directly at the aircon that detects it is running on battery now.
          As @SunEagle said, it is difficult to provide a solution unless one knows the wiring. Where you place the hybrid inverter would make all the difference in how expensive it would be to rewire the AirCon. Installing a hybrid inverter will require some rewiring. Do you know how many Amps your hybrid inverter will support? You may be forced by code to rewire if your hybrid inverter can not support your whole house main panel anyway.

          Typically the Thermostat is wired to the AirCon which provides the 24 volt signal to run the Aircon. Perhaps an alternative would be to intercept that with another relay controlled by the grid power. That would be a simple dumb relay. Running low voltage wire is less expensive. There are lots of smart relays but finding a trigger when the grid is down is the difficult part, especially finding one that would not require software which might fail to work in an outage.
          9 kW solar, 42kWh LFP storage. EV owner since 2012

          Comment


          • #6
            Just an awareness note - not all systems completely power down with a simple thermostat OFF command. Some are HEAT_FAN_COOL_OFF and some compressors do a short cycle daily independent of the the thermostat.
            your mileage WILL vary
            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


            • #7
              I agree that needs to be investigated. My preference in any event would be to have a critical loads panel but we haven't heard answers from the OP about details of the wiring and the capacity of the proposed hybrid inverter. Without those answers it is difficult to further speculate. .

              To me the important question that should be answered with any backup power system is, what loads need to be powered by the backup? The cost of whole house backup needs to be evaluated versus the cost of adding a critical loads panel and using a smaller inverter and less batteries

              Even wiring a remote controlled breaker that trips when the power goes of might be more expensive that a critical loads panel.There is no fail safe guaranty that it will work either.
              Last edited by Ampster; 04-11-2020, 09:33 AM.
              9 kW solar, 42kWh LFP storage. EV owner since 2012

              Comment


              • #8
                Originally posted by Ampster View Post
                I agree that needs to be investigated. My preference in any event would be to have a critical loads panel but we haven't heard answers from the OP about details of the wiring and the capacity of the proposed hybrid inverter. Without those answers it is difficult to further speculate. .

                To me the important question that should be answered with any backup power system is, what loads need to be powered by the backup? The cost of whole house backup needs to be evaluated versus the cost of adding a critical loads panel and using a smaller inverter and less batteries

                Even wiring a remote controlled breaker that trips when the power goes of might be more expensive that a critical loads panel.There is no fail safe guaranty that it will work either.
                I agree that some type of critical load panel is needed to minimize what needs to be powered. I currently have a 12kw generator that can safely backfeed into my home but I still have to turn off some loads so it does not get taxed. At least it will run my home AC unit along with power for my refrigerator and internet equipment but I still have to turn off a few AC loads in my sheds. I rather do that manually the trust some type of automation.

                Comment


                • #9
                  Just a thought wire in a latching contactor at each unit then they would drop out on power failure and would be necessary to reset after power is restored. they could also be reset while on batteries if needed. It is easy to make the contactor latching. check internet or utube on How to make a latching relay (contactor) .
                  Wayne, Virginia, usa.,13kw tracking gt.

                  Comment


                  • #10
                    Originally posted by wayne23836 View Post
                    Just a thought wire in a latching contactor at each unit then they would drop out on power failure and would be necessary to reset after power is restored. they could also be reset while on batteries if needed. It is easy to make the contactor latching. check internet or utube on How to make a latching relay (contactor) .
                    Yes I have seen a diagram for one. It may fit the OPs requirements for an automatic switch. The advantage is that it would have instantaneous response and be fail safe. What I mean by fail safe is that when the power drops the relay opens, it does not require a software response like a smart switch might require.

                    A question was asked in another thread about any damage to an Air Conditioner compressor if it was abrubtly turned off and my sense is that it would cause no more damage than a power outage. The risk is starting it again before the pressures equalize. A latching relay would reduce that risk.
                    Last edited by Ampster; 04-11-2020, 06:48 PM.
                    9 kW solar, 42kWh LFP storage. EV owner since 2012

                    Comment

                    Working...
                    X