Regarding rooftop solar PV: I spent three years in that business, designing and selling rooftop systems for customers in the San Francisco Bay Area, where the solar insolation is in the same range as what you have in South Africa (1500 kWh/m2 or higher). I know that in most cases, with an unshaded south-facing roof or yard, its straightfoward to design a PV system that generates 100% of the house’s electricity needs, as averaged on an annual basis with a grid-connected system. The systems I designed have performed as expected and produced that amount of power in the real world. With a few solar thermal modules, it’s also possible to heat nearly all the domestic hot water. (Heating and cooling the house as well requires more power, and depends heavily on how well-constructed and insulated the house is.)

As to the issue of subsidies, there are effectively no energy sources of any kind that are not, at some level, subsidized. Oil and gas have been subsidized with an array of direct incentives, tax credits, accelerated depreciation schedules, and so on for 150 years now, and are STILL subsidized to the tune of hundreds of billions of dollars a year. Coal is heavily subsidized by allowing the vast majority of its real-world costs (air pollution, mercury permeating the environment, acid rain, the environmental damage from mining, and so on) to be externalized and not priced in to the commodity–a massive unrecognized subsidy. Large hydro plants are always subsidized with federal money and loan guarantees. Nuclear plants are heavily subsidized by federal loan guarantees (the nuclear industry in America is currently seeking $100 billion in federal loan guarantees), liability limitations, pushing the cost of waste handling and cleanup onto the public, externalizing the costs of nuclear fuel mining, processing, and upgrading, and so on.

In short, there is no such thing as an unsubsidized energy source. All of it is, at one level or another, built using “other people’s money.”

As for cost: I have spent hundreds of hours attempting to find good, current, accurate, inclusive data on the real cost of building, operating, and decommissioning nuclear fission plants, in order to make an apples-to-apples comparison with renewables like solar and wind. Pity the fool who would attempt to find such data! Most of it is horribly outdated (from the pre-2005 era, when all commodity prices began to march upward relentlessly) and the analyses of nuclear costs invariably leave out massive chunks of the real world costs. However, inasmuch as I have been able to locate reasonably contemporary data, and adjust it for comparison to the current, all-inclusive data on renewables, it appears to me that solar and wind are now cost-competitive with nuclear plants…and if you plot some reasonable cost curves for renewables and nuclear plants, the renewables become considerably cheaper 20-30 years in the future (because the fuel is free and the maintenance is minimal). This is a horribly complicated subject, however, and the devil is very much in the details. There are very few good studies in this area, unfortunately.

For another view of the economics of nuclear power vs. renewables, see this July 2010 article in the New York Times on a recent academic study showing that when costs are properly accounted for, solar PV is now cheaper than nuclear power: “Nuclear Energy Loses Cost Advantage.”

As we approach the peak and decline of all traditional primary energy sources, the questions increasingly become practical ones: How can we generate kWh in an affordable, scalable, deployable fashion? I have concluded that it’s easier (and a whole lot faster) to round up the capital to build rooftop solar generation than it is to build nuclear plants, with the latter’s immense capital costs and extremely long lead times. Distributed generation also offers a grid resiliency benefit that I believe will become increasingly important going forward. This is why I conclude that all energy sources we might hope to exploit in the future face serious scaling challenges–nuclear energy is absolutely no exception to this. We must do it all–and if my calculations are correct, we will still far short of what projected demand will be. As the saying goes, there are no silver bullets, only silver BBs.

I have read several of your submissions waxing enthusiastic over PV ‘Rooftop Solar’.

Most of the ‘math’ gravitates around funding and subsidies to ‘get it off the ground’ as it were, a kind of Keynesian approach of ‘priming the pump’ by reallocation of productive output from more successful enterprises to less successful ones, (bureaucracy and regulation being the least ‘successful enterprises’ of all in an economic sense)

Any funding transferred to renewable energy enterprises is in effect an energy input which was derived from the existing energy base.
Due to the primacy of energy in the production of every human good and service, it makes no sense to ‘subsidise’ an energy source, and an energy technology which cannot sustain itself in the sense that its own output is sufficient to continually maintain itself as well as produce a viable net output is worse than useless.

Rooftop Solar PV may well power the lighting, TV, computers and other frivolous devices, but don’t expect to cook the family dinner and bath the kids, let alone maintain a bearable indoor temperature in more challenging climes in existing structures to which these panels are to be fitted.

I have examined what is available in the real world, made some measurements and did some simple arithmetic.
With the best panels I could locate, with full dual axis tracking, at midday in summer with clear skies in sunny South Africa, about 36 square meters (387 sq. ft) of panels would be required to bring a single kettle of 1.5liter (2 quarts) to the boil in 3 minutes.
This is a trickle in relation to the consumption of western civilisation, and persons curtailed to such daily energy flows would be considered ‘poor’.

The average Australian consumes 33Kwh of electricity per day, equivalent (by my measurements) to 66 square meters of solar panels per capita,( working 8hr per day under continuously ideal conditions) for a population of some 21 million, which is only about one sixth of total, all up consumption, including liquid fuel equivalents.

‘Renewable” energy advocates continuously dodge the energy density issue by insisting that the solution lies in a ‘mix’ of technologies, but once the fossil inputs are removed, the millions of years of solar concentration and consequent energy density are gone, and cannot be gotten back, because incoming solar is harvested dynamically.

We are only here in such numbers in the first place because the energy derived from the multiple oxidative states carbon became available.
The advent of unprecedented human population growth and the advent of fossil energy exploitation is no coincidence, and even the increased agricultural output, which is also the ‘renewable’ dynamic harvesting of solar energy through photosynthesis, increased in step with increased energy input in the form of fixed nitrogen (derived from hydrocarbons via the Haber Bosch process), albeit with diminishing returns.

The actinides, a kind of remaining ‘Big Bang’ fossil, are the only materials which realistically have the potential, by way of fundamental physics and thermodynamics, to realise a massively increased and reasonably sustainable energy density, way above that of current chemical energy systems.

That same fundamental physics and thermodynamics constrains what can be realised by ‘renewable’ systems in absolute terms, not a lack of research, Federal funding or political will.
What most regard as human ‘progress’ and desirable increases in affluence and welfare, (as opposed to poverty) have always been marked by an increase in energy consumption, a migration from a lower energy density base to a higher one.
A reversal of these fortunes will quickly disperse any objections to nuclear energy as the day to day realities imposed by decreasing energy flows start to bite.
We may nevertheless still fall into the ‘Olduvai Gorge’ without realising its potential, but that will be because of intransigence and stupidity rather than because of the inescapable and inevitable of some apocalyptic vision.

I like PV panels, so long as my neighbour does not expect his installation to subsidised at public expense, or the manufacturer expect his business to be likewise propped up with other peoples money.