A passive solar house that is losing heat to the outdoors at an average rate of 50,000 kJ/h is maintained at 22°C at all times during a winter night for 10 h. The house is to be heated by 50 glass containers each containing 20 L of water that is heated to 80°C during the day by absorbing solar energy. A thermostat-controlled 15-kW back-up electric resistance heater turns on whenever necessary to keep the house at 22°C.
(a) How long did the electric heating system run that night?
(b) How long would the electric heater run that night if the house incorporated no solar heating?

Transcribed Image Text:

Water 80° Pump