Our power was out recently for SIX days due to HIGH winds. The first couple of days without power wasn't too rough. We had a generator keeping the important things powered like the refrigerator, freezer and my grow lights. On the second day without power my husband had gone outside to add some gas to the generator and couldnt get it restarted! He tried & tried eventually giving up & went & bought a new one, the last one on the shelf. The old generator was 5000 watts and the new one was 1600 which meant we couldn't run as many appliances on it. To my dismay my grow lights, exhaust etc didn't make the cut. My plants already had spent a day in the dark. I knew I had to do something. I didn't want them to go into flower! I knew that low light was better than no light so I went to Home DePot and purchased a clip on lamp also with an LED bulb. My husband ran an extension cord from the generator to the lamp. I felt less stressed about the situation for sure. We were without power for six days and my plants did just fine during the crisis. Yay! Crisis alleviated!
If I couldn't run a light in there what would have I done? I probably would have removed them from the room and put them somewhere warm where they'dl get light during the day. If they were in flower I would have put them in a closet or a spot where they wouldn't get light after twelve hours. I'd use a box if I could and seal it so no light could get in. You have to get creative. Power outages can be a growers nightmare, especially if your plants are too big to move or you can't move them out of their location. Another option would be a battery operated lantern.
I'm grateful that we have a generator & I was able to run a light to prevent flowering. It was colder in there too without the metal halide & HPS running. It didn't get below 70. I'm just glad it's over with. I was getting tired of camping inside our house.