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[aprssig] APRS Solar Power (I was wrong)

Robert Bruninga bruninga at usna.edu
Thu Oct 1 18:57:18 UTC 2009


If you have heard me speak recently and I compared my Solar car
to Solar panels on the roof of your house as not economical, I
WAS WRONG.  I was overlooking many recent changes in the
environment:

1) Solar panels (PV) are 1% of what they cost in 1970
2) PV dropped 40% due to 2007 Energy Boom and 2009 economic bust
4) $5,000 to $20,000 tax and cash back incentives for YOU
5) Grid-tie systems operate at 95% efficiency compared to 70% of
battery systems
6) Local electric rates DOUBLED in the last 2 years
7) Laws require utilities to pay you the same peak rates they
charge you.
8) Solar Energy credits can gain an additional $275 per 1Kw
system per year
9) Payback is at least 10% per year or better
10) The same money in the bank gets 1% interest

So I was wrong in not keeping current with all the changing
environment, and now I am full speed to get my system approved
and built and correct any miss-guidance I helped propagate.

Pardon. I am claiming this particular email is on-topic because
of public statements to the contrary I have made on APRS and ham
radio emergency power systems.  But this hot topic should
probably spin off elsewhere.  We need a HAM Solar Power group
somewhere...?

Summary:  Do NOT make the mistake (as most of us do) of thinking
in terms of stand-alone Battery back-up solar power systems .
They are NOT worth it (in most places where you have access to
the grid).  They cost $5 to $10,000 more, are only 70% efficient
(compared to 95% for grid-tie) and are a never ending
maintenance headache.  Instead, most any enterprising ham should
be able to provide his own backup power using a cheap $150 1 kW
inverter running off his car's 12V system for any power outages.
That, a few deep cycle batteries, (and using CFL lightbulbs in
your house) will give you enough emergency power to operate your
full Ham station, all the lights in the house you want plus your
refrigerator for as long as you can buy gas.

And even if your grid-tie solar array produces nothing (in the
way of AC power) when the grid goes out, you still have many
Killowatts of DC power on your roof, that you can surely find
lots of things to do with until the grid comes back.  For
example, have the electrician wire a 250 volt string of the 200
Watt solar panels in the array to a DPDT switch so they can be
disconnected from the Grid Tie system and the 250 VDC can be
available to you.  THen you can plug in as many modern DC/DC
pwer supplies into that 250 VDC to give you LOTS of amps at 12
volts, or ... almost any modern gizmo has a universal power
supply input that will run on anything from 110V to 330V DC as
is.

Anyway, for similar hints www.aprs.org/FD-Prius-Power.html

Sorry for the off-topic.  But  I was wrong. PV works! (even in
Maryland).  If you live in the SW, you are lucky, and it works
TWICE as much or at HALF the price!

A Born-again Home PV junkie
Bob, WB4APR




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