SMA is a German company that makes some of the best solar pv inverters around. These are the bits of kit that are fed the DC electrical output from your solar panels and converts it to AC suitable for exporting to the national grid (through your standard electricity supply). They store a lot of data about what is going on, such as generation power and units produced. There is a nice display on the inverter that shows current status and cumulative output, plus a 24-hour graph.
Unfortunately the inverter is almost always put in the loft, so to make things easier the SMA inverters have a bluetooth interface that allows you to get inverter readings out without having to be stood in front of it. At least, that's the theory! In our case we can't get a bluetooth connection unless we stand with our laptop PC in front of the inverter, and even then the Sunny Explorer software (supplied free by SMA) is very slow to connect to the inverter - up to a minute. Our laptop is of a decent spec (HP Elitebook just over a yaer old) but maybe the built-in Bluetooth isn't decent enough. There are reports on web forums that a USB bluetooth dongle has succeeded where built-in bluetooth has failed, so maybe that's worth a try. Read more at Whirlpool forums.
One crucial mistake we made when trying to operate the bluetooth connection was to get the password wrong. The default password for the user is 0000, but we didn't notice that and tried 'password'. Oddly enough we were able to connect but couldn't download any data; there were no notices that the password was wrong, and all we got was a message saying that we should "wait whilst the data is being downloaded". If you find yourself waiting more than a minute or so for a data download, have a think whether you put in the correct password - it won't tell you!
If you want to try the Sunny Explorer software, you can download it from www.sma.de/en/products/software/sunny-explorer.html; download their PDF user manual if you get stuck. Note that they only have a PC version (Microsoft Windows XP, Vista or 7, 32-bit or 64-bit), and that back in March 2011 a Mac version was only in progress, with "no fix date of release yet". People talk about using Sunny Explorer on a Mac by running it through a virtual machine such as Parallels, but even then you may have to use a USB bluetooth dongle instead of the built-in one.