> The total electricity consumption in the Netherlands lays around 110,000 GWh and increases annually by about 3% (according to CBS Netherlands). This means that if all suitable roofs in the Netherlands would be equipped with solar panels, they could only supply approximately 25% of the Dutch electricity demand.
Even though not every rooftop has one yet due to the cost of it (and some people find it ugly, like my father, he absolutely does not want us or our neighbors to have it :/), in the long run there is also not enough space. At least, that's what the company who makes this material is saying. Even if they are biased and we assume it's only half as bad as they tell us, we're still at only 50% of the demand.
Source: http://www.solaroad.nl/en/faq/ (under "Why would you include solar cells in the road and not next to it or on rooftops?")