I looked at the AC current flow in both directions. The diodes on the gates make the triacs work like plain old diodes.
If I'm right, the 4 triacs and 4 diodes make up a simple full wave bridge Rectifier..
Having 120 hz positive pluses appear on the left side of the cap, doesn't seem like it's going to do much magic.
So, a full wave driving a series cap & battery.
Depending on the size of the cap, it Kinda looks like a
battery charger, but the battery is connected
backwards..?.
So, does that mean it's a battery dis-charger?
If it is a dis-charger,
does the battery's power end up on the grid??
~~~
For sure, I would connect the AC via an isolation transformer..
No sense getting killed..
And maybe a Variac adjustable autotransformer to feed the isolation transformer!!