Good point. If you were to use solar electricity to produce hydrogen by electrolysis (for use in cars, say) an average supply works just fine.
The capital cost of the IFR must be huge on a per watt basis. A 1 GW conventional nuclear plant will run about $4 billion. which is $4 per Watt. An IFR would be at least double, maybe triple that so $8 - $12 billion not including development costs. While an IFR if very efficient, it does use fuel and has a significant operating cost. Accepting that my figures for cost may be out by a factor of 6, that puts solar at today's prices about $12/watt. So it I appears to me that solar would be competitive. A big advantage of solar would be the speed at which it could be implemented.