Posted by Eeyore on May 10, 2009, 4:14 pm
Ron Rosenfeld wrote:
Very optimistic if you mean by that 5 kWh /day.
The data's readily available.
Only 4 of many locations listed make 5 or better in the CONUS.
3.5 - 4 would be nearer the mark ( anyone fancy averaging all those numbers )
and don't forget to consider population distribution vs location too as to how
effective it will be for how many people.
Not to mention different energy profile usage requirements vs time of the
year. NY does OK with an average 3.53 but that falls to 1.4 in December when
it's cold and you want heat.
Now something like one of these in say Arizona might do well.
PV solar will always be most effective in the Tropics.
Posted by Ron Rosenfeld on May 11, 2009, 12:48 am
On Sun, 10 May 2009 17:14:14 +0100, Eeyore
No, I mean 5 kWh/M2/day
That is a rather limited subset of the 1400+ monitoring stations.
The average of the limited apricus data is 4.095 kWh/M2/day. It took less
than 60 seconds to import the data into Excel and compute an average.
The data published on the NREL web site, also readily available, is 1800
kWh/M2/year as an average for the US. 1800/365.25 --> 4.93 kWh/M2/day. (or
Eyeballing the PV Solar Radiation Annual map for Flat Plate, Facing South,
Latitude Tilt (for CONUS), I would say the NREL value is more accurate than
the apricus subset.
That is not relevant to the question being asked. So if you want to answer
that question, feel free to formulate it and do the analysis.
Again, the question being asked had to do with energy to produce a solar
panel vs energy produced by the panel. To me it makes sense to average
production over a large area when trying to answer that question.
If you want to take the position that the energy payback will be longer in
an area of limited insolation, vs an area of above average insolation, I
would not argue with that.
As a matter of fact, if you limited PV sales to those areas with above
average insolation, energy payback would be even quicker than what has been
Posted by Eeyore on May 11, 2009, 11:01 am
Ron Rosenfeld wrote:
m2 actually but that was what I meant.
Are you deliberately suggesting they missed all the hot spots ? Promoters of PV
solar will naturally tend to inflate their figures and fail to disclose losses.
So I was pretty close.
It's relevant to its practically in NY or New England for example.
Sensible calculations excluding 'subsidies' which are other peoples' taxes and
including all true costs including cost of capital indicate a system is unlikely
pay back in your lifetime or ever.
Posted by dold on May 12, 2009, 12:42 am
Here's another cost, the water needed for operations.
Excluding the end user subsidies would make no sense, because those
subsidies are in place. Those subsidies are part of the full financial
On the other hand, without those subsidies, your gross exaggerations are
just untrue. They might increase the time for payback in dollar terms, but
not stretch them to "ever", and they have no effect on the watt for watt
payback, which was the question of this thread.
Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5
Posted by Ron Rosenfeld on May 12, 2009, 2:22 am
On Mon, 11 May 2009 12:01:40 +0100, Eeyore
Please explain in detail how dollar subsidies affect the energy used to
produce a solar panel?