Time to put some numbers to this.
Solar drying uses zero electricity or fuel, but does not work on rainy days.
Electric dryer uses electricity to evaporate water. It takes 1050 BTU's to evaporate one pound of water. That's 0.310 KwH plus extra heat to heat the air that's exhausted with the evaporated water. Total is about 0.50 KwH per pound of water evaporated. If you exhaust the dryer into the house, that heat goes into heating the house, along with the moisture and the lint. If an electric dryer is exhausted into the house, each pound of water evaporated will also add about 0.5 KwH (1706 BTU) of heat into the house.
Condensing dryer is the same as hanging the clothes in a room with a dehumidifier running. In that case, the heat stays in the house and the water goes down the drain. The total heat into the house is sum of the heat from the electricity (1 KwH = 3412 BTU) plus the heat of evaporation of the water (1050 BTU per pound of water collected).
I have a high efficiency dehumidifier rated at 4.7 pints per KwH. Each pound of water removed and run down the drain will put 1/4.7X3412 + 1050 = 1775 BTU into the house while using 1/4.7 = 0.21 KwH of electricity.
The condensing dryer uses less than half the electricity and puts almost twice the heat into the house. It does this without adding moisture into the house.
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