[aprssig] Solar, then vs now

Bob Bruninga bruninga at usna.edu
Mon May 23 13:59:30 EDT 2011

> I ran some calculations a couple years ago for my house 
> in upstate NY.... It would never have even come close 
> to breaking even during my expected lifespan.

Which is the point of this recent discussion!  We were so wrong back then!

Depending on what you mean by "a couple of years" and what you *assumed*,
the difference between then and now could be 2 to 40 times more cost
effective today than it was "a couple of years ago"...

I had the same conclusions back before the 1st week in August 2009 when for
the first time in years, I actually looked at the new math.  I was shocked
to see that I was *so wrong* by a factor of over 30 to 1.  Here is why I was
so wrong:  I had overlooked these recent factors:

1) The cost of electricity in Maryland went up 50% recently (X1.5)
2) The cost of solar has dropped in half in the last few years (x2)
3) I overlooked the 50% government credits (x2)
4) I was using the idea of battery storage (x3)*
5) I overlooked the annual SREC payments (x2)

Multiply all those factors 1.5 X 2 X 2 X 3 X 2 = 36.  I was wrong by a
factor of 36 to 1!  That is why I sound so born-again.  I was so wrong with
my old thinking on solar and want to share my conversion...

> The only solar system that would have made even a 
> moderate amount of sense was solar-assisted water heating.  
> And even that would have been iffy.

Do the calculations again (now), and make the right assumptions and you will
be absolutely amazed at the results (if your state is progressive)...


* Note:  If one does not understand why the useful energy from an off-grid
battery storage solar system is only 1/3rd that of a grid-tie system, please
see www.aprs.org/off-grid-maybe.html

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