With gas heating and reservation of the whole house, one module of 2 kW/h is enough for 3-4 hours of continuous operation. By reserving the whole house is meant the power of all the electrics: lighting, refrigerator, laptop, alarm, kettle, boiler pumps, sewers, etc.
If the heating is electric, then 5-6 capacity modules will be needed. However, we do not recommend reserving an electric boiler, as it is very energy-consuming. Modern homes hold heat well for up to 24 hours. And the average time of emergency outages is approximately 5 hours.