> It assumes Government subsidies for solar, which may be going away for political reasons.

Residential solar costs average out at 15c per kWh, post 30% tax credit. If the credit goes away, the 20c per kWh generation cost is still competitive compared to utility's retail rate. The bet is on solar technologies to continue incremental gains in efficiency, pushing the final price per kWh down.

In the commercial and industrial world the cost can be driven down significantly since the installations are larger (4c per kWh is the lowest I've seen), and the one-time installation costs are recouped faster, so that sector is likely to grow with or without tax credits. It's subject to the same efficiency metrics as consumer-grade tech.