I wouldn't want to pay that much because a stand alone battery probably costs less, but if I could pay $500 for some kit that let me use my tesla as a power sou

I wouldn't want to pay that much because a stand alone battery probably costs less, but if I could pay $500 for some kit that let me use my tesla as a power source for my house at night I would be very interested. This would make sense to me as I have panels to charge it during the day, having a few KWH at night time would be pretty efficient. The stand alone batteries are too expensive right now.