Building your own tubes sounds cool. However, not very practical or inexpensive.
You can buy a pre made unit for nearly the same cost.
This unit comes with 18 tubes, stainless steel tank and a rack to hold it all together for
$1100 shipped.
Solar Water Heater NF Pressurized 200 liters by solarfox
This one is less, but no tank or rack.
solar water heater by solarfox
I hope to buy one of these sooner or later. (hopefully sooner)
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