<html>
<body>
<font size=3>Friends:<br><br>
Forgive me if this point has already been made:<br><br>
When designing PV feeders, one typically looks at the Impp of an array
for current specifications. Impp is rarely achieved, however --
only a handful of days per year and for only a short period of time
per day. This is particularly true for a fixed
array.<br><br>
I took the hour-by-hour data from the PV watts tool, subtracted out the
zero values (night time) and averaged the remaining values. The
result was about 50%.<br><br>
Therefore, a 2% VD at Impp is actually a 1% VD on average. This
gives a bit more headroom in any PV feeder design.<br><br>
William Miller<br><br>
<br>
At 04:25 AM 4/9/2010, you wrote:<br>
<blockquote type=cite class=cite cite>IMHO it seems like we're all really
on the same page here...... trying to make<br>
the the most out of the the resources we have available to work
with......sun<br>
hours, pv, copper, labor, dollars, etc. Job specifics come into play.
There are<br>
definitely times when a detailed cost/ benefit analysis is called for.
Many<br>
other times, let's not miss the forest for the trees, an increase in wire
size<br>
to avoid waste of other aforementioned resources, is low hanging fruit.
As a<br>
percentage of the overall system cost, the decision is a no
-brainer.<br><br>
Dick Ratico<br>
Solarwind Electic</font></blockquote></body>
</html>