Now you’ve built your solar collector to heat your hot water. What are you supposed to do with all that left-over heat that just fades away during the night while the water it sitting in the collector and hoses? Build a solar hot water tank for that heated water and enjoy it the next morning, too. If you size your solar hot water (also known as thermal storage) tank correctly, you can easily store the heated water overnight and it will be plenty hot enough to provide comfortable showers or clothes laundering water. This video – another one from G. Scott Davis – shows you just how to do that.
If you have a supply of food safe 55 gallon drums, you may want to build your thermal storage tank using them. The water never gets hot enough to have to worry about making the HDPE of the barrels soft. You can just plumb them so your solar collector feeds into the first one, which feeds into the next one, and so on until you get to the last barrel. The last barrel feeds back to your water intake on your solar collector. The chain of barrels can be enclosed in an insulated “box” to help preserve the heat.
This other video tells you everything you need to know about stratification in your solar hot water tank. (Fast forward through the first two minutes if you don’t like politics mixed with your solar.)