🚀 go-pugleaf

"ant" <dont-look@evil.spam> wrote in message news:MR5_4.7628
>
>
> my real point was that the electricity utility could do the things i was
> talking about, home roof top installed and utility owned solar panels are
> already happening in America. also if you look at the amount of solar
> energy falling on your average roof and the efficiency of the current
> generation of solar cells i think the figure is about %50 coverage in
> America and %30 in Australia and the homes energy needs are met.
>

So, if I recall, a unit of insolation is 1kW/sq.m, at high noon when the sun
is shining, with a collector directly facing the source.  In my city of
Victoria, BC, we get an average of 3 hours of full insolation per day over
the year--less in winter, more in summer.  That is, a perpendicular
collector would collect 3kWh per sq.m per day.

Now, let's assume for a second that PV's are 100% efficient, and that my
house has an array of them directly facing whatever sunlight there is.  For
my small house's average daily power consumption of 35kWh in winter, I would
need (35/3=) 11.7 sq.m of PV's.  Well, that's doable.

But wait.  PV's are in fact only about 25% efficient, maximum (that's what
BP and Siemens claim for their PV products).  So we actually need four times
the area of PV's--46.8 sq.m minimum.  That's almost all of my roof.

But wait.  These are roof-mounted PV's, right?  So they're not facing the
sun directly, and there are trees in the way when the sun is low during
winter.  Furthermore, some of these PV's have to be installed on the north
side of my roof, and that gets very little sun in winter.  So we'll have to
add more collectors--somewhere.

But wait.  This is winter, remember, and it rains all the damn time here in
winter--you can go a week without seeing the sun (remember, I said 3hrs
insolation average).  It's not that windy, either--don't get your hopes up.

And how do we get these panels on the roof?  Well, someone installs them.
That's quite a risky business, manoeuvring a set of heavy panels into place
and securing them on a steeply graded surface, 20 feet or more above the
ground.  I dare say it's riskier than roofing, which according to the US
Bureau of Labor Statistics, was the 6th most dangerous occupation in 1997,
with a risk 5.9 times that of the average worker.  Ant, how many workers are
you willing to sacrifice on the altar of "clean" energy?

Not to mention all the environmental nasties that go into PV panels and
which have to be junked and replaced periodically.  Not to mention the
environmental problems with batteries and their inherent and unavoidable
inefficiencies.  Not to mention the damn expense of doing all this to
everyone's house.  Not to mention the ugliness of a city with PV's on every
roof (I like my new reddish brown shingles just fine as they are thanks -
they match the house).  Oops, that's right--we've got to convert to AC.
Inverter efficiencies are pretty high, but it all adds up.

On the other hand, we have centralized power.  Baseload, 24/7, and more
kicks in when needed.  I don't worry about whether my family will have warm
showers in the morning in winter.  We use Hydro, and it costs me just shy of
6c/kWh.  I'm gradually improving the energy efficiency of my house when I
can afford it, but there's a certain irreducible amount of power that I will
always need.

Ant (why these ridiculous pseudonyms?).  Convince me I should switch.