ATS – Automatically switch between solar/generator and main incoming grid power
Let us work with our automatic transfer switch
When working with automatic transfer switches there are a couple of things to consider. Firstly if you are going to break the neutral or not and switch that one over. In some occasions you are not allowed to break the neutral and for some inverters you need to break it since the inverter does not share the same neutral as the grid does and you would get strange behavior. There can also be issues when it comes to how fast you are allowed to switch and if the inverter isnt in sync with the grid when switching this can cause issues with the appliances. Also if you have a 3phase system hooked up and the grid is connected in 1 way and your inverter have the phases switched all the way around you will or can get issues with motors for instance. Ie for those who have worked with 3phase motors know that they will change direction if the phases aren’t aligned in correct order. I don’t think your motor will like switching direction before they are stopped 🙂 An automatic transfer switch are something that everyone should have with alternative power.
Lastly don’t forget to talk to your electrician before its done!
So with that said i publish some drawings below that potentially work!
Automatic transfer switch diagrams
Below setup is the optimal setup where you have a control unit that determines how long it should be between switching and switching back. Most of them can also monitor the voltage on the incoming so you only switch if its stable enough.
On this design you will have a DPDT switch. This switch allows you to choose between which of the sources that are the priority source hence then goes back to that one as soon as there is power. Its worth mentioning that you have nothing protecting against flapping power so you could get unwanted scenarios where it switches back and forth all the time.
This last one is the simple one where you statically have set Solar to be priority. In this case you do not need any more things added except the wires to get it going.