Is this any help? CARBON FOOTPRINT OF ELECTRICITY GENERATION (published ~2006, so may be out of date)

Photovoltaics (PV), also known as solar cells, are made of crystalline silicon, a semi-conducting material which
converts sunlight into electricity. The silicon required for PV modules is extracted from quartz sand at high
temperatures. This is the most energy intensive phase of PV module production, accounting for 60% of the total
energy requirement.