so Ive got a question for you, seeing as you are a coder!

I want to get people more interested in the performance of their solar thermal systems, but getting monitoring sorted out is, at the moment, very expensive.

Given that many controllers have some kind of data interface in the form of a TTL/USB port, which can be used to network the controller it shouldnt be too difficult - they already sell equipment to do it. But it costs about £250 at trade price, and what they are selling you is basically a re-branded router with some fancy firmware, that probably cost about £30 to make, if that.

So... can you think of a way of doing that much much cheaper? say using a rasberry pi or some other hobby kit? And what problems do you face taking the data output and making sense of it? there is already software for interpreting the data available for free and easily accessible: