The added use of soap-nut detergent makes it even more efficient by being biodegradable and can be used to water your plants with.
Washing dishes this way won't save as much energy as the amazing Satellite CD Solar Oven, but it makes the daily ritual of cleaning your plate sacred by actively respecting Water and Earth.
First hand account of using soapnuts.
More practical information about using soapnuts and links to several online soapnut retailers from North America, UK, New Zealand and Australia: soapnuts.
Step 1: Prepare Soapnut Detergent
3 quarts (litres) water
Step 2: Simmer 30 Minutes
Step 3: Strain
Step 4: Storage
This liquid can also be used as a vegetable and fruit wash, all-purpose cleanser (great on floors), laundry detergent, shampoo or to get aphids off a favorite plant.
Soapnuts are anti-bacterial and anti-fungal, efficient cleaners but they don't suds up to the degree we are accustomed to these days, but have no fear. Your dishes are as clean as can be.
Step 5: Prepare Dishes for Washing
Step 6: Clean Out Sink
Step 7: Fill Sink
Step 8: Add Detergent
The water will suds up, but the suds quickly subside. Don't worry the soapnut detergent is still doing it's job.
Step 9: Wash Dishes
Step 10: Remove Used Dishwater
Step 11: Dish-Water Your Plants
I'm looking into growing my own soapnut plant next -- then it will truly be cradle to cradle dishwashing.