During the summer the Saudi Arabians guzzle about a million barrels per day not to drive or to manufacture petrochemicals but to generate electricity. In round numbers that's 100 million dollars a day in potential oil sales. If you assume a 40% conversion efficency you can get right around 666 kWh from a barrel of oil. A BOTE calculation reveals that the opportunity cost of the electricity generated from oil is in excess of 15 cents/kWh. If the Saudis could find something like say photoelectrics that produced electricity for 7.5 to 10 cents/kWh they'd clearly save a lot of money.
The same value substitution logic used with Saudi Arabia can be applied to Norway. Norway gets 99% of their electricity from their hydroelectric dams. Hypothetically, if the value of the electricity from their dams exceeded the cost of the electricity from solar it would be in their best interest to install solar.
One might reasonably ask... How could the value of hydroelectricy ever exceed the cost of solar? It's a fair question but remember that 10 years ago oil sold for under $30/barrel and photoelectrics cost four times what they do today. A lot can change in 10 years.
What could change in electricity markets to make Norway's hydroelectricity more valuable than solar electricity? Here are two general possibilities.
1. Hydoelectric dams can be used to provide regulating services in addition to generic kilowatt-hours. In high variable power scenarios you need a lot of regulation - high demand for regulation services raises the value for those services. Is it enough to make hydro more valuable than solar? Probably not but it will make things interesting.
2. Electricity pricing dynamics have changed significantly over the last decade as wind and solar resources have entered the market. It's difficult to project how these dynamics will evolve over the next decade but we can speculate. An often overlooked dynamic when it comes to solar vs. conventional power is that solar makes conventional power more expensive by stealing market share. In 2012 solar stole an additional 7 TWh of market from conventional power plants in Germany. This means the production costs at the effected conventional power plants actually went up due to their fixed costs being divided by lower production. If this trend continues we can imagine a lot of Combustion Turbine power plants going out of business. When you take those CTs out of the equation it changes the supply/demand picture - prices during the winter peak or the summer shoulder periods could become quite peaky with fewer CTs left to compete for that market. This is where hydro from Norway swoops in and makes a go of it.
This is all meant to be a thought exercise... The product (solar in Norway for example) isn't important here. The process (value substitution) is what I'm trying to get at.