Transfer switch for battery back-up

[electro7]

Hi,

I need some help here. I have installed a battery back-up system with Sunny Islands and Sunny Boy's. Instead of pulling specific circuits to the critical load panel I installed an automatic transfer switch so that when utility power goes out it would transfer the load to the critical load panel. When I went to test the system by turning off the main breaker the transfer switch never transferred from utility to the critical load (or the terminals where the generator wires would normally land). There was voltage on the critical load side of the transfer switch where normally the generator wires hook up. I am using a Generac 100 amp transfer switch. Am I missing some control wiring? Or are the Generac transfer switches only meant for generators? If so is there a way around it?

Thanks for your help!

 

[ggunn]

Hi,

I need some help here. I have installed a battery back-up system with Sunny Islands and Sunny Boy's. Instead of pulling specific circuits to the critical load panel I installed an automatic transfer switch so that when utility power goes out it would transfer the load to the critical load panel. When I went to test the system by turning off the main breaker the transfer switch never transferred from utility to the critical load (or the terminals where the generator wires would normally land). There was voltage on the critical load side of the transfer switch where normally the generator wires hook up. I am using a Generac 100 amp transfer switch. Am I missing some control wiring? Or are the Generac transfer switches only meant for generators? If so is there a way around it?

Thanks for your help!

Without seeing the whole design it's a bit hard to comment specifically, but in a lab situation I tried to build a system with a grid connection, Sunny Boy and Sunny Island, and a Generac generator with its transfer switch, and there was indeed some reason why it wouldn't all work together. I could get the SB, SI, and grid connection all working like it was supposed to, and I could get the SMA inverters and the Generac all working in off grid mode where the SI would start and stop the genny in response to the battery bank SOC, but I could never get the whole assembly to work with the transfer switch to the grid. It was indeed something to do with the transfer switch, where the gear would get into a state where two components would sit there each waiting for the other to do something.

It was over three years ago when I was doing this; I apologize that I cannot remember all the details, only that with the Generac transfer switch and generator (at least the ones I had) and the SB/SI setup, it all wouldn't work together and it wasn't just operator error. I haven't thought about this in a long time; if my failing memory shakes loose more details I'll jump back in here and tell you.

 

[electro7]

Okay thanks for that. I am thinking it has to do with the transfer switches as well. Like you said I am able to get the back-up with the Sunny Islands and SB's to operate when I shut down the main but for whatever reason the transfer switches do not transfer from grid to critical load (instead of hooking up the generator on these terminals I connected the critical load panel so that it would back-up his house sub-panel). I may need some other relay/contactor I am thinking?? So the way I wanted it to work was that when the grid goes down the transfer switch I have connected to his house sub-panel would transfer from the utility to the critical load panel and would thus feed his house in a power outage situation.
Let me know if you think of anything else. Thanks.