"HeyBub" wrote in message
m...
RBM wrote:


A 6KW system for a home costs about $48K. This means that it is
totally unviable compared to other electricity generation options.
The only way it becomes viable is for the govt to hand out more money
to get you to install one. After the gov pays for around half of the
cost, then it can make economic sense for the homeowner. For the
taxpayers, it's a loser.

In general, people aren't stupid. If solar energy was cost effective,
we'd all be tripping over each other to get it.

It's not just "cost effective," it's generally impossible.

The amount of radiant energy falling on the earth is 120 watts/sq meter.
At the equator. At noon. With no clouds. Adjusting for latitude, 12 hours
of darkness, clouds, and time of day, one would average about 1/3 the
maximum, or 40 watts/sq meter. An 1800 sq ft house would capture, then,
(assuming 70% efficiency of the solar collector) 560 watts, or about 1/2
kw.

That's enough for one light bulb (non-CFL), and one TV or one computer.
Forget about the fridge.

You can nibble at the margins, but you can't run this country - or an
average house - off of sunbeams, irrespective of the cost.


Methinks you left off a zero: Should be 1200 W/m^2.
Nominal 100 W/sq ft.

Ackshooly, it varies from 900 to 1500 W/m^2, depending on lattitude,
altitude, etc.

Selective-surface collectors can substantially exceed 70% -- good mostly for
HW (heat, domestic), which can be a big % of used juice. Also, these
collectors are proly a lot cheaper than photovoltaics.
You can make pretty good ones DIY, as well.

PV's are up to what, now, 15% efficiency??
And I thought I read somewhere that PV's could be had for about $1/watt???

Also, I wonder what the lifespan of PV's are.
--
EA