As you may recall, for the past couple of years I have used a solar shower. It worked okay but it took a couple of hours to warm up even in the heat of Aticama. It finally broke so I needed another way to heat water.
We use a lot of black hose at the house and at the orchards. The fact that the water came out hot got me to thinking that if I used more hose I could get enough volume of hot water to bathe. Leaving the coiled hose on the patio table in direct sunlight provides almost 5 gallons of hot (probably 120 degrees) water in less than an hour.
In addition to the patio bathing, the water is a great temperature for doing dishes and laundry!