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Wrenches,<br>
A good client of ours is a rancher in the New Mexico/Arizona border
area. He has a specific need for which I couldn't offer a simple
system.<br>
<br>
He needs to raise water from a lake 400+/- vertical feet to a 100K
gallon storage tank for agricultural use. The site is remote. The
amount is substantial - about 10-12 gpm continuously, 24/7. He would
like to use 4 Grundfos SQ Flex pumps at about 2.5-3 gpm, each
running array-direct feeding a common pipe to the tank. He then
wants to use about an 8kW (derated to 6kW for 7,500' elevation)
diesel generator (with standard two-wire automatic start) to run all
four pumps when the sun goes down, and shut off and transfer back to
PV when the sun comes up the next morning.<br>
<br>
How might this be done? If we assume that each pump has four 210W
modules, that would be an 80Vnom array with MPP around 120V and Voc
around 150V. I would assume that both of these voltages are too high
to use any stand-alone AGS, such as Atkinson or Magnum. We
considered a separate tiny 12V or 24V battery with small PV module,
used just to power an AGS voltage sense signal, with the voltage
difference between float (13.6V) and rest (12.7V) triggering a
voltage-actuated start signal, but rejected this as problematic as
battery temperatures affected charge voltages. A self-contained time
switch, such as some of the newer Intermatic units, might work, if
the right model can be identified and isn't a substantial phantom
load.<br>
<br>
We would also have to adapt a relay to switch between sources, with
a 120 or 240 V AC relay coil current, energized by the generator.
The Grundfos IO101 AC interface unit is manual only.<br>
<br>
Has anyone solved this problem? Any ideas for a reasonably simple
and trouble-free approach would be welcome.<br>
Thank you,<br>
Allan<br>
<br>
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<font face="Times New Roman, Times, serif"><b>Allan Sindelar</b></font><br>
<small><a href="mailto:Allan@positiveenergysolar.com"><font
color="#000099" face="Times New Roman, Times, serif"><u>Allan@positiveenergysolar.com</u></font></a></small><font
face="Times New Roman, Times, serif"><br>
<span style="font-size: 10pt;">NABCEP Certified Photovoltaic
Installer<br>
NABCEP Certified Technical Sales Professional<br>
New Mexico EE98J Journeyman Electrician<br>
<b>Positive Energy, Inc.</b><br>
3201 Calle Marie<br>
Santa Fe, New Mexico 87507<br>
<b>505 424-1112</b><br>
<a href="http://www.positiveenergysolar.com/" target="_blank"><u>www.positiveenergysolar.com</u></a><o:p></o:p></span></font>
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