Looking ahead, one posits that a demand-side shift is an inevitable Power Efficiency Guide eventuality and that Spain was just the trigger. If not Spain, something else would've come along to kick us in the butt.
In the case of gasoline a limited availability, refining/ processing capacity and cost all decide its price. The same is true converting coal to electricity. In the case of the PV-grade silicon to PV panel vertical though, we need only reckon with processing capacity and costs. There's no raw material shortage registering on the radar screen, at least not for the next couple of thousand years. As such, except maybe for a few years around 2012 when we expect PV electricity generation to hit grid-parity, the availability of PV-grade silicon may tend towards oversupply well into the future.
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