What a pity solar panels don't grow on trees. Oh, yes, of course... they do. (Also in shrubs, herbs, and pond scum, making sunlight plus water and air equal sugar. Imagine a world covered in solar panels, a world still pleasant to live in...)

What we want (as opposed to food energy, which we merely need) is power for machines. In the next few years, cheap, durable, reasonably efficient photovoltaic films will be brought to market by at least some of the people now searching for such technology. There's so much solar energy available that those who can afford it will then have energy aplenty for a while, and will be free to discover new ways to depend on it. ("Invention is the mother of many necessities." Marshall McLuhan)

If we're going to use roads anyway, at least let us collect sunlight with them to power electric vehicles and other industry. Roofs can be used also, but where it's possible to support the weight of both soil and snow, it would be more efficient in the long run to grow food on roofs. (The hitch so far is that where life is, moisture is, and decay follows. Having to tear out and rebuild a green roof within a few decades wouldn't be cost- or energy-efficient. Insurers and builders remain wary of it until they see it proven.)

Meanwhile we'll start to fight over water and food supply. The solar energy boom will help processing and transportation, but the new use for land will further squeeze cropland and wilderness. Caring citizens are the most effective defenders of healthy local ecologies that deliver clean water and air, and eat up pollution and pests. Musicians, please help people remember why we need hedgerows and tangled braes in our neighbourhoods.