I took a look at the data sources available and there is some information that is consumable via an RSS feed (click the RSS link towards the bottom of the page) which you could pipe into the Chumby RSS widget. This doesn't list your current stats though as shown on the graph. The graph itself is an image, but the issue is the image path changes, so there is nothing solid to point to, in which case I would have recommended imageURL. The one last thing could be trying to get a hold of some of the data with Yahoo Pipes, but I have not had a chance to look into that yet.
You could also send SolarGuard an email asking if there is, or will be, a user facing API available (maybe they have something in beta). There are a couple of other related apps for chumby providing data on energy related systems, for example here and here. If SolarGuard provided even the simplest API it wouldn't be hard to build. They could even contact me if they had any questions as to what would need to be provided.
Wish I had a quicker solution for you.