The sun could be meeting a quarter of the world’s
electricity needs by 2050, the International Energy Agency (IEA)

Today it published two solar technology
roadmaps: one for solar thermal electricity where heat from the sun
is used to heat liquid and drive a turbine; and another for the
more familiar solar photovoltaic cells.

The IEA says that by 2050, solar PV could be
providing 16 per cent of the world’s electricity. Solar thermal
could account for another 11 per cent, it thinks.

The march of solar PV

Solar panels have been spreading across rooftops
around the world like a rash. Installed solar PV capacity has
increased by half again each year for the past decade, as the chart
below shows.

IEA solar PV technology roadmap 2014

Much of that growth has been in Europe,
particularly in Germany, Italy and Spain where generous subsidies
had driven deployment.

Those subsidies have been cut, leading to
reduced installation rates. But other countries have started to
pick up the slack.

Worldwide solar PV capacity reached 135
gigawatts in 2013, the IEA says, up by 37 gigawatts on the previous
year. 2013 was also the first since 2004 in which more capacity was
added in Asia than in Europe. China, with 11 gigawatts, installed
more solar PV in 2013 than all of Europe put together.

In total the IEA sees the current 135 gigawatts
of solar PV capacity growing to 1,721 gigawatts in 2030 and a
massive 4,674 gigawatts in 2050. That would be able to generate
around 16 per cent of global electricity needs.

To get a sense of how much solar that actually
is, total
installed global capacity
for all forms of
generation was 5,331 gigawatts in 2011.

Recent regional trends are expected to continue,
the IEA says, with China adding the most new solar PV capacity out
to 2050 (lilac area, below).

IEA solar PV technology roadmap 2014

The cost of solar modules in 2013 had fallen by
80 per cent over five years, the IEA points out, though costs have
since stabilised. Even so, system costs have continued to decline
as industry experience grows.

Solar PV systems can already produce power at
costs similar to gas or even coal in the right locations, the IEA
says, though the cost of financing investment in solar may be
higher than for traditional energy sources.

Grid parity, where solar power costs as much to
produce as average electricity, was reached in 2013 in Germany,
Italy, California and Australia, it says. The IEA notes that
increased rates of solar deployment bring other issues, such as the
need to strengthen power grids, and these problems may carry
additional costs.

It acknowledges these challenges and says
options including electricity interconnectors, energy storage and
efforts to manage electricity demand will all be needed.

It’s also important to note that as with
predictions of the future
, the IEA scenarios
depend heavily on how the relative costs of power generation evolve
and the way in which any barriers that arise are

All the same it’s encouraging to note that at
least in some parts of the world solar PV is getting to the point
of being cost-competitive.

The slower rise of solar thermal

The story of rapid solar deployment is continued
for solar thermal plants. Their capacity grew from 600 megawatts in
2009 to 3.6 gigawatts in 2013 worldwide (chart, below). That’s not
much compared to solar PV for now, but capacity has been growing
fast – at 30 to 60 per cent per year since 2009.

IEA solar thermal electricity roadmap

Currently worldwide capacity for solar thermal
is about the same as the planned nuclear plant at Hinkley Point in
Somerset. However solar plants don’t produce power round the clock
and through the seasons in quite the same way as

One big advantage of solar thermal plants is
that they are able to store heated liquid to smooth out power
production once the sun sets. In effect they can have in-built
energy storage capability. Solar PV plants can’t manage this

You’ll notice from the chart above that so far
almost all solar thermal capacity has been installed in the US
(orange area) and Spain (blue). These countries have one thing in
common – lots of sun and plentiful empty space.

You can see how important sunshine is in the
IEA’s expectation for the growth of solar thermal out to 2050.
Almost all the growth in output is expected to come from parts of
the world that are close to the equator, as the chart below


IEA solar thermal electricity roadmap

If the IEA scenario turns into reality, solar
thermal capacity around the world would increase from today’s 4
gigawatts to 261 gigawatts in 2030 and 982 gigawatts in

Almost all of this would be in the US, China,
India, Africa and the Middle East. The EU would have just 28
gigawatts, compared to 118 in China and 229 in the US.

This new roadmap is less optimistic than the
projections the IEA made in 2009-10, however. It had expected 147
gigawatts of capacity by 2020. It now says an extra seven to ten
years will be needed to pass that milestone.

What is means for the climate

The IEA’s solar technology roadmaps emphasise an
argument it has made several times before: that tackling climate
change need not cost the earth.

The IEA says that decarbonising the energy
system by 2050 would produce net savings of $71 trillion.
The marginal
of renewing energy infrastructure with
low-carbon supplies instead of carbon-intensive sources would be
$44 trillion, it thinks. But this would be more than offset by
savings in avoided fossil fuels of $115 trillion.

The IEA specifically addresses concerns that the
emissions produced during manufacture of solar panels and the
variable nature of the electricity they produce reduces the
emissions savings expected.

It says:

“Modelling by the IEA and others shows that the
penalties incurred due to the manufacturing process
and the variability of PV are minor compared with the emission
reductions arising from fossil fuel displacement.”

These kind of forward looking exercises have to
be interpreted carefully, as projecting thirty-five years into the
future is a challenging task.

But if the IEA’s 2050 vision for solar is
achieved, then 6 gigatonnes of carbon dioxide emissions would be
avoided each year – 4 gigatonnes from solar PV and the rest from
solar thermal.

That would be a significant chunk of the effort
needed to cut current annual emissions from
close to 40 gigatonnes
to perhaps 50 per
cent lower by 2050. If the world is to avoid dangerous climate
change, this is probably part of what success looks