Solar pv: Exponential Growth!

Freiburg, Germany. An early solar pioneer

Freiburg, Germany. An early solar pioneer

I’ve just finished reading ‘The Switch’ by Chris Goodall about how solar photovoltaics will become the dominant source of global electricity production. The key point Goodall stresses throughout the book is the effect of the learning curve and how this has been bringing down prices by about 20% every two years and how total installed capacity has doubled every two years. This exponential trend has been going on for decades, but back in the 1970s and 1980s the biannual doubling was from a few kilowatts to a few more kilowatts, then a few megawatts to a few more, so generally photovoltaics were considered insignificant by mainstream commentators. Solar enthusiasts were an easily dismissed fringe group.

This exponential rate of growth has continued. In the last few weeks the global installed capacity of photovoltaic panels passed the 300 GigaWatt milestone. A couple more doublings and we will pass the TeraWatt level. Of course exponential growth on a finite planet cannot go on forever. However it does look as if solar power will keep expanding extremely rapidly for the foreseeable future, whatever politicians like Trump and Putin might do to try and stop it. There are a number of technical innovations in the pipeline that make continuing falls in production costs inevitable, and then simple economics means that rates of deployment will continue to increase.

Over the last two years China and Japan have lead the world. Globally about 1.2 billion people are not connected to mains electricity and at least another billion experience frequent power cuts due to poor grid infrastructure. Most of these people live in Africa and South Asia and it is in these regions that I would expect solar to grow most quickly over the coming decade. For the rural off grid tropics solar plus batteries is already cheaper than either diesel generators or connecting up to distant electricity grids. They will leapfrog the need for grids.

This week I was talking to someone in Herefordshire who is renovating a cottage and putting sufficient solar panels to run his air source heat pump and all his family’s electricity needs for most of the year. Smart technology will determine when appliances operate and when to store electricity for later use. An electric car could easily be added to the mix. Although still connected to the grid he envisages buying and selling as little electricity as possible. If half hourly metering comes in it will become profitable for him and useful for the grid managers, for him to buy electricity at times of weak demand and sell it at times of peak demand. In his renovation insulation and air tightness have been improved to minimize winter heating requirements. Globally such possibilities are opening up as the technology evolves. Within a decade I think it probable that hundreds of millions, or indeed billions, of households will operate in this manner. In the process they will make coal, gas, oil and nuclear power obsolete.

In colder cloudier climates wind, tidal and geothermal energy will undoubtedly have a major role to play. Batteries will be important for short term energy storage. There are an increasing number of emergent technologies focusing on interseasonal energy storage, such as renewable liquid fuels and gases, many of which will be created with surplus summer solar energy.

Solar still has a long way to go to become the dominant energy source, but if exponential rates of growth continue this might become the reality far faster than most people expect. Last year China more than doubled its solar capacity in a single year. Many other countries will more than double their solar capacity over the next year or two, and I’ll write about the most exciting examples on this blog. The Solar Age is coming.

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