I am staring out of my office window at dull, gray skies. There is little sign of that mythical blue-biased Rayleigh scattering. There is a light drizzle, however, that comes and goes. But there is no breeze to bristle spring buds on the trees, no gusts to push the propellers of a local turbine. There are a few birds - blackbirds, starlings, pigeons, the occasional band of goldfinches, darting between the micro-droplets of the rain to grab crumbs and arthropod nuggets from the ground and the trees. If only we can filter the force from their feathers.
It is on interminably gray days like these, as I type at my fullycharged laptop with my equally electrified smart phone by my side, that I am glad we are not a solar-only household. That we are not reliant in totality on photovoltaic semiconductors to grasp at photons and shuffle their energies into electron movement. If we were, I would of course be simply staring out of my window, perhaps strumming an acoustic guitar, waiting patiently for sufficiently high numbers of those vague photons to impinge on the slick silicon burnishing our southward roof top and bring the battery power levels up to a high enough level to boot my laptop and drive the internet router that drives me across the globe from the safety of my padded swivel chair.
As regular readers know, the capacity for solar energy research is boundless, there are endless rounds of research papers published, news articles abstracted and promises of a sustainable future made. Great strides are taken almost on a daily basis with the next great material emerging from some laboratory somewhere that nudges up the quantum efficiencies, tightens the bandgaps and ultimately loosens the fossil fuel grip on our power supply ignoring the nuclear family and the dammed hydro supply. Solar farms are spreading slowly across agricultural land that no longer has the tilth to grow the fruit and vegetables of which we are urged to ingest increasing amounts. As energy companies withdraw from offshore wind, the pressure is on sunlight. The research and development must find ways to devise panels that can harvest the limpest of light waves and channel the resulting current into equally novel super capacitors. Unfortunately, we are not there yet.
We can look forward to a bright energy future. But, you will really have to wish very hard for sunny days. If climate change is going to give those of us in the so-called temperate zones more gray skies than blue, then that is the ultimate irony that solar would sink. There is really no solace for the solar powered in Dolly Parton's pre-Glastonbury Festival idea that you have to put up with a little rain if you want rainbows. Rainbows don't get the laptop booted up after all...
David Bradley blogs at http://www.sciencebase.com and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".