Solar: No possible doubt whatever

Of that there is no manner of doubt-- 
No probable, possible shadow of doubt-- 
No possible doubt whatever.

[The Gondoliers.  G & S's gentle mockery of hereditary monarchy.]

From Tony Seba's latest speech:

Solar's cost has been falling by 11% a year for 4 decades.

In recent years the cost decline appears to be even faster.  4 years ago, solar cost 8 cents/kWh ($80/MWh) and in sunny places it now costs < 1.8 cents/kWh ($18/MWh)  Unsubsidised.

Not only is solar now often the cheapest source of energy, in many geographies it is cheaper than the operating costs of coal and gas.  In 80% of global markets the cost of solar is below grid parity, i.e., below the retail price of electricity.  And that ignores potential technological wild cards, such as the new perovskite solar which can be easily manufactured by ordinary glass factories and is as cheap as glass.

In consequence, installed solar capacity has been doubling every 2 years since 1990. Currently, solar PV provides about 2% of the world's electricity.  In 5 doublings--10 years--it could provide 64% of the world's electricity.  Of course, the growth rate will slow as supply reaches saturation.  And it is limited by the cost of storage.  The next few doublings in solar won't be a problem for grid stability,  but after 16% (i.e., in 2024) a rapid increase in storage will be essential.

Fortunately,  the cost of batteries is plunging.  If battery costs fall 16% per annum, that means they will decline by 60% in 5 years.

In fact, since 2010, the rate of decline in battery costs has further accelerated to 20% per annum.  This means battery costs halve every 3 years.  In 6 years, battery storage will cost 25% --or less--of what it does now.  The cost of 24 hours of storage for an average household will be below $1 a day.

I've sliced and diced Seba's arguments, and I strongly recommend you watch the whole presentation.

There are some very clear conclusions:

• The moral of the story is that by 2024 storage costs will not be an impediment to solar reaching 64% of total global electricity supply.  
• Solar will provide something like half our power within 10 years. The rest will be provided by wind and water, wind especially in higher latitudes.
• The grid will have substantial battery backup both at grid level and behind the meter.  In fact battery storage will be ubiquitous.
• Coal is finished.  Any new coal power stations built now will be stranded assets within a decade or less.  Given that they are supposed to last 30 years, that will be financially disastrous.  
• High quality coal will still be needed (for now) for making iron and steel.  Low quality coal mines are another lost cause. 
• Countries which insist on staying with coal will face much more expensive electricity than those which ditch it.
• Peaking gas plants are in trouble too.  Batteries are faster and cheaper, and will get cheaper still.
• If you add in the explosive growth of EVs (sales doubling every 18 months), CO2 emissions from burning fossil fuels will start to fall rapidly within 5 or 6 years.  Not because governments and the elite have suddenly turned green, but because of sheer selfish motives by millions of energy users.
• The carbon bubble is a serious risk to world financial markets.
• Utilities will face a big decline in demand from households and businesses with their own rooftops (blocks of flats and office blocks are different.)  It will be cheaper for them to install rooftop solar and batteries than to use grid electricity. In fact, the cost of the grid alone will be more than the costs of (distributed) solar and storage.  That means that even if generation costs zero, it would still pay households/small businesses to install their own solar/battery combo.