How to tell if the grid is down with automatic grid tie battery back-up system?

I ( and the electrician) just installed a Schneider Conext grid-tied battery back-up system in the basement with PV arrays out in the yard. I really like the system. During simulated grid down tests the switch over to off-grid battery power is 100% seamless. Their is not even the slightest indication that the switch has occurred.
This is great but how will I know the switch has occurred when I am not in the basement? Is their something I can do to too alert me that the grid is down? Alarm? Emergency light? Some sort of light that I could run up from the basement into the house?
Without knowing the grid is down I will not know to move into "off grid power conservation" mode. I could drain my battery bank and not know it until the generator kicks on to recharge the bank (at night)...and hopefully I will hear it.
I am stumped? Any Ideas?
Comments
-Bill
All of my lighting circuits and most other 120 circuits are backed up via UPS so I've considered a similar solution for my own home, but I have more details, below.
Use a circuit from the inverter which is switched via a normally-closed relay, with the relay powered by a utility-powered circuit. Power goes out, whatever is on that relay lights up. Either a 120 volt light, or if it is easier to run low-voltage where you need the light, plug in a 12 volt transformer. If you drive an LED or two the low-voltage power drop won't be an issue (but you'll need to size the resistor for the LED to account for the LED's load and the voltage drop if you make a long run).
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