[aprssig] Shack backup power

Bob Bruninga bruninga at usna.edu
Thu Jun 2 09:48:19 EDT 2011

>> I assume everybody on here has a full time
>> low current emergency powered off-grid APRS station...

> In less than 12 hours from the time the lights 
> went out, the only outbound comm capability 
> I had left was ham radio.
> I'm wondering if solar and batteries aren't the 
> way to go. That may be a way to ease into solar 
> power at home.

Just recognize that economical solar power, and battery storage are over 99%
completely different issues.  Economical solar runs 99.9% of the time versus
what you do during the 0.1% without the grid.  Although I learned to
completely avoid battery storage in the interest of home-solar economics
(see my web page: www.aprs.org/off-grid-maybe.html) every ham of course
needs a small backup battery system for his shack, and a few lights.

So I need to update my web page to not sound so anti-battery and come up
with the modest shack system.  I allude to it in my Power Point that began
this whole thread, but it is buried under a lot of other stuff.

A single deep-cycle marine battery should be able to keep some
communications and lights going for a day.  This solves the short-term
blackout problem and can be charged by something as simple as a $5
wall-wart... no need for expensive solar to charge the battery, because then
for the next 99.9% of the time, the solar power is doing nothing. (wasted).

BUT, if you want CONTINUOUS LONG TERM black-out power, then you need an
order of magnitude bigger solar array...  Again. Two completely different

But here is my recommendation (that I need to weave into the above web

1) A deep cycle 12v battery for back up comms and a light
2) A modest 220W solar panel 
3) A modest solar charger
4) AND a plug-into-the-wall 250W grid-tie inverter

This item #4 then takes all the rest of the 99.9% of the solar power (once
the batteries are charged up) that you are generating and makes sure that it
gets used in your house economically.

Something like that.
To power the Refrigerator for long term backup, a small generator would do
nicely... or a 1200W inverter on your car...



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