On Tuesday, 11 June 2013 at 20:02:29 UTC, Walter Bright wrote:
On 6/11/2013 12:21 PM, John Colvin wrote:
On Tuesday, 11 June 2013 at 18:47:35 UTC, Walter Bright wrote:
On 6/11/2013 8:28 AM, Adam D. Ruppe wrote:
It is great stuff, solar power is almost free money if you
can wait 20 years for
it.
Yeah, but you'll have to replace it before 20 years!
Source? There's not much that wears out in a photovoltaic
AFAIK. The associated
electrical components may break however, especially on some of
the more complex
setups.
Don't have a source, I read it long ago. Note that none of the
advertisements, brochures, etc., mention expected life of the
PVs.
That's not correct. Almost all manufacturers provide a 20 or 30
year warranty.
Warranty periods have been slowing increasing as the industry has
gained field experience.
I do know that the life of any semiconductor is measured as the
integral of the heat it experiences. Heat causes the doping to
migrate, and when it migrates far enough the part fails.
That's true for certain kinds of dopants (it's particularly true
if you have copper involved), but dopant migration is not an
issue for any commercial solar modules that I know of. (The
situation may be different for exotic technologies). This is
because solar cells are very simple devices, they're just
enormous diodes.
Virtually all solar module failures in the field are caused by
mechanical issues (bad solder joints, cracks, delamination), not
by semiconductor degradation.
PV panels can get pretty hot in direct sunlight.
They do. Still not as hot as a CPU though!
Heating/cooling cycling will also cause cracking.
Most of these problems were solved in the 80's.
We were continuously doing accelerated lifetime testing of our
own modules and ones from various manufacturers. Temperature
cycling, humidity freeze, hail impact testing (that's fun), wind
load testing (that's really fun), etc.
For some silicon modules you can get oxygen-boron complexes
induced by UV, which causes a slow reduction in power, but our
modules survived 200 years equivalent UVB exposure with no
degradation whatsoever.
Circuit boards, inverters, etc., also fail, and you'd need some
assurance you can get replacement parts for 20 years.
That one is definitely true. Even worse is batteries for off-grid
systems, batteries have a very short lifetime.
