Solar hot water controller

Well its been a while since I last updated, I managed to get some time over the last month to build a solar hot water controller for the navitron evacuated tube system we have installed here on our house, its been a project I wanted to do for a while. I've documented version 1.0 of the design here:

Apart from the usefulness of being able to log data from the solar hot water controller I'm interested in looking at combining data from the solar hot water controller with data from the energy monitor. It would be interesting to see if its possible to calculate accurately how much immersion heating is displaced by the solar hot water system as well as how well the system is working compared with its expected output.

Here is a graph of the different system temperatures plotted with flot

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