I've been thinking about this. Do you/anyone happen to know if it's a decently efficient use of the stored energy? I love the idea of our hot-water boiler acti

I've been thinking about this. Do you/anyone happen to know if it's a decently efficient use of the stored energy? I love the idea of our hot-water boiler acting as battery (potentially along with another actual electric battery). I have a handle on the hardware, but not on the efficiency of it. Thanks,