Monday, October 31, 2011

A $1K Solar Water Heating System AND Open Source Differential Controller

Nathan did a really nice job of building and documenting his solar water heating system.  

The system is an offshoot of the $1K solar water heating systems with some useful new design features.
The twinwall glazing is a very nice look.
The system uses the usual 300 ft coil of PEX pipe as the heat exchanger, but Nathan recoiled the PEX for better heat transfer performance:
The 300 ft of PEX is recoiled into a two layer coil for
more water exposure to each coil.
Be aware that this recoiling can be a challenge -- think about about your method if you don't want to end up imprisoned in a coil of angry PEX.

Nathan also offers details and source code for making an open source Arduino based differential controller.
Arduino based differential controller.
Nathan has the Arduino based controller equipped with an Ethernet shield.  This allows the Ardduino to log data directly through his router to an free online logging service called -- there is no need to have a PC running 24/7 for this kind of logging, and it gives you access to the data from anywhere -- very nice!

All the details on Nathan's website....

For more on the $1K solar water heater and dozens of other DIY solar water heaters...

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