If you choose to stay at this place, here is a message you can expect from the host Carla roughly an hour after you check in:
"Hello! I hope you are enjoying your stay! Please be aware that San Diego Gas & Electric runs on a tiered schedule and I do reserve the right to charge an additional amount if the bill is high - please know this will not occur without notice to you via message in this center and will not occur if the bill is under $500. However, I have had situations where the bill runs over $1500 per month for monthly visitors, thus the kind request to be cognizant about your energy usage. The normal on-peak price is from 4 p.m. to 9 p.m. Therefore, you'll want to be extra careful to reduce your energy use during the hours of 4 p.m. to 9 pm. when you are being charged both the on-peak price and CPP Day price for electricity. Thank you for understanding!"
I've never had this with any Airbnb I have stayed at (and I have stayed at many!) and would never book this house again with the threat of a surprise $500 bill after a stay. I have reported her to Airbnb's customer service.