This is very interesting to me James!  I have a handful of DIY projects on my farm that have saved me both time and money and your project would be one that would benefit me, and others, greatly.  By background was IT and I've learned a lot of electrical in the 14 years I've been on the farm full time.

You said you don't want leave your full time job which is fine but if you want to generate revenue off your project you could consider designing a website that instructs others how to build your system.  Build a set of plans, written instructions, and provide links to all the necessary pieces.  If custom software is involved provide it for download. Sell the plans and software for what you feel is a fair price.  If you do your documentation well enough you don't have to offer support.  Create a facebook page where users can ask and answer questions but make sure you are not on the hook for all technical support.  You could generate a small income stream with not a lot of ongoing effort......I'd probably but it!