Brian has been using solar panels and solar collectors in his house for some time. Earlier he used an Arduino and IOIO board for data logging. But lately he moved to well known Raspberry Pi platform that gives much more space to work with.
Still using a Raspberry PI for such task is quite an overkill but its fun indeed. It pulls sensor data from various sensors including i2C Microchip MCP980, 1-Wire DS18B20 on solar collector; ACS712 current sensor in low voltage part and mains current using Elkor i-Snail-VC transducer. Raspberry Pi has MCP3428 16-bit ADC on-board to read transducer values. Since Pi board runs Linux it is obvious that all hard job is done using Python. Brian even made a custom DC-DC power supply that fits nicely on top of Raspberry Pi board. His future plans are to push data in to MySQL instead of using direct HTTP GET upload method.