If you have solar photo voltaic panels it's good to know how much is being generated so you can choose when to use power such as the tumble dryer. Using power locally, from the panels, is much more economical than receiving the feed-in tariff and buying power back at other times.In a previous home we installed a PV solar system that had a Fronius inverter. I was impressed with the low RF noise emitted by this product and pleased to find that it had a JSON producing web service endpoint that I could poll to see how much power was being generated.
At our new home there is a system with micro-inverters and an Envoy controller. The micro-inverters do produce noticeable RF noise but bear in mind that this is a very low noise location so I might be a little sensitive to it.
It turns out that this system also has JSON producing web services. The system, once I figured out how to connect to our Wifi, has a web interface at http://envoy.local
By enabling Developer mode in the browser I was able to see that the web page calls back to endpoints including: