Fun project - use an Arduino microcontroller for this, run it from a small solar panel, measure the voltage with a voltage divideron the analogue input, and use one of the Arduino's outputs to close a contactor to short a module when V>590 or so. Cost would be about $60.   <div class="gmail_extra">
<br><br><div class="gmail_quote">On Thu, Nov 29, 2012 at 10:05 PM, mac Lewis <span dir="ltr"><<a href="mailto:maclewis1@gmail.com" target="_blank">maclewis1@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Larry,<div><br></div><div>You could make a device that does this via relays by either sensing temp, single panel or string voltage, and takes a panel or two out of the circuit when necessary.  Maybe there is a product made for this already available.</div>

<div><br></div><div>Good luck<br><br><div class="gmail_quote"><div><div class="h5">On Thu, Nov 29, 2012 at 6:53 PM, Larry Crutcher, Starlight Solar Power Systems <span dir="ltr"><<a href="mailto:larry@starlightsolar.com" target="_blank">larry@starlightsolar.com</a>></span> wrote:<br>

</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"><div style="word-wrap:break-word">Wrenches,<div><br></div><div>I seem to recall seeing something about a device for PV string over-voltage protection by bypassing a module. I can't find any info by Goggling.</div>

<div><br></div><div>Some customers in the FAR north, ay, can see > 40° below zero with bright sun and snow reflection. I want to be able to switch off one or more modules in a string for protecting the controllers.<br>

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<div><br>Thank you,</div><div><br>Larry Crutcher</div><span><font color="#888888"><div>Starlight Solar Power Systems</div></font></span></div></span></span></div></span><br></div></span><br></div></span><br>
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