[ExI] [tt] Smaller, cheaper, faster: Does Moore's law apply to solar cells?

Eugen Leitl eugen at leitl.org
Tue Mar 22 08:03:56 UTC 2011

On Mon, Mar 21, 2011 at 07:00:30PM -0700, spike wrote:

> Moore's law isn't applicable to PVs for so many good reasons.  Even if we
> ignore the fact that Moore's law has been extended so far beyond what it was
> originally proposed to describe, it still isn't applicable to solar cells.

Moore's laws, at least in 2d photolithography will be shortly
over. We should see 8 nm, though that's going to be damn difficult.
But the only way to continue is to go up into the 3rd dimension.
That technology won't be there in ~10 years.

> We are going to hit a wall soon with the cost of raw materials of solar
> cells.  In microprocessors, the magic was in finding new and clever ways to

Do you realize that CdTe uses 12 g/m^2? I presume CIGS is about
the same. Carrier substrate is a metal foil or floatglass. 
Think of this as moderately expensive construction material.

> miniaturize integrated circuits, so more could be done with less raw
> material.  

You're exactly correct in that PV is about scaling up surface
area, but that's just one part of the issue. You need power electronics,
though that can be integrated into the panels themselves, and
most importantly, you need to upgrade the grid, add smart meters
for dynamic pricing, long-term add storage, increase degree
of electrification for missing fossil gases, liquids and solids,
build up synfuel and chemical feedstock infrastructure, retrofit
existing natural gas infrastructure for increasing degrees of
hydrogen, and so on. None of this is Moore. It's a long, expensive
slog through infrastructure space, only an order of magnitude
larger than the last shift from phytomass to fossils.
> With PV, I would argue we are within a factor of about 2 of the lowest cost
> they will ever be.  That is good enough to make them worth having, but it

Absolutely not, the exponential decay will continue for the next 20, 30
years at the very least -- it should be half the price of today's
dirty coal electricity in less than 20 years. And of course plants 
do it completely for free, so eventually we will be able to create 
self-replicating photovoltaics.

> creates a whole nuther set of challenges having to do with load leveling
> technology.

Right, right now Germany has to limit PV installation rate because
during peak it produces far more (over 10 GW) than the grid can
comfortably handle. Add a blustery, sunny day and suddenly you
realize you're having a giant problem on your hands.
> When I see articles extrapolating PV costs way down exponentially without
> reasonable justification, those immediately go into the bit bucket.

The PV panels do that, the power electronics do that less strongly.
This is reflected in my daily reality: every second damn barn is
tiled with PV panels. 
> It surprises me: Scientific American has historically been such a careful
> magazine.  They seem to have gone way down in their standards.

Scientific American used to be good, but it was in 1960 and 70s.
The article you're criticizing (much too harshly) is a blog, not
the print edition.

Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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