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<font face="Times New Roman, Times, serif">Bob,<br>
<br>
Are you seriously suggesting that hams tap into what is a
potentially lethal power supply, without warning about the dangers
such a scheme presents, not to mention the legal implications in
places like Australia?<br>
<br>
I can understand your desire to pursue alternate and emergency
power sources but safety MUST come first.<br>
<br>
Ray vk2tv<br>
</font><br>
<div class="moz-cite-prefix">On 20/01/16 07:12, Robert Bruninga via
aprssig wrote:<br>
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cite="mid:d12dd44388eb5a9ddc603516deff4eed@mail.gmail.com"
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<p class="MsoNormal">Emergency Power your Ham stuff on solar
panels.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Today I tested 5 different laptop power
supplies to see if they would run on a 72 VDC solar panel. </p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Yes, every one of them would work until the
load exceeded the raw power available from the solar panel and
the solar panels current limited voltage crashed. Most would
then cycle, trying to restart until the load was reduced to
match the power available. One though, would go to LOW
impedance and I assume would blow a primary fuse if the DC
source had more output.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Note, these supplies are typical universal
100-240 VAC 47-60 Hz and all worked down to 72 VDC input (the
max-power voltage) of the solar panel. One of them was picky
about which polarity was applied to the input cord, the others
didn’t care. I couldnt test at lower voltage because the
panel voltage rapidly goes to near zero when the peak power
point is exceeded.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Reason for this test is the bunch of 40
Watt 72v solar panels I got (VOC=100v). These panels are
obsolete, but any 2 modern panels in series will easily give
several hundred watts at around 72 volts. But when fully
loaded to the rating of the panels 500W (typical Vp of around
30v each, you might want three panels in series giving a full
500W output at around 90 volts. </p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">These universal supplies also work on up to
330 VDC input too.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">So, the best tap point on your home solar
panels is around 300 VDC (typicaly the mid point of a string
of solar panels oprating up to 600 VDC). These laptop
supplies also work just fine on 300 VDC input too (remember
240 VAC peaks at 330 VDC). Taping into your solar array at
around 300 VDC can deliver almost 1500W from a solar array.
The problem is that most of what you need during a power
outage do not use universal switching supplies, but need 60 Hz
power (Well pump, refrigerator, etc). But for modern
electronics with universal supplies, you’d have more power
than you need forever.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Some added detail is on this web page:</p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="http://aprs.org/camp-solar.html">http://aprs.org/camp-solar.html</a></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Bob, WB4APR</p>
<p class="MsoNormal"> </p>
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