<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META content="text/html; charset=iso-8859-1" http-equiv=Content-Type>
<META name=GENERATOR content="MSHTML 8.00.6001.19019">
<STYLE></STYLE>
</HEAD>
<BODY>
<DIV>I should have taken a picture of power lines from the proposed
location. I need to get better information about distance and angle.
However, I am estimating that the power line is about 25' from proposed
collectors at 45 degree angle. The lines are above winter angles. If
45 degrees is correct, this put it in direct sun patch in March and
September. This is just a typical neighborhood power line. 3 lines
are thin, likely no insulation. 2 lines are thicker with insulation.
These may be communication cables like telephones. </DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV>. . .</DIV>
<DIV> <STRONG>:</STRONG></DIV>
<DIV> I</DIV>
<DIV> I</DIV>
<DIV>
<DIV> I
/</DIV>
<DIV>
<DIV> I
/ </DIV>
<DIV> </DIV>
<DIV>
<DIV>Kieth Winston wrote:</DIV>
<DIV>Well, it also depends on specifics of the install: how close the wires are
to each other, if their shadows line up along the axis of the modules, etc. At
the very least it's likely to be a good candidate for a microinverter install,
to minimize shading effects.<BR><BR></DIV></DIV>
<DIV>Howell Mayhew wrote:</DIV>
<DIV>If you use Enphase module-inverters (one inverter for each PV module) then
any shaded module wouldn't affect the PV array's performance, because each PV
string is a PV module.<BR></DIV>
<DIV>My comments:</DIV>
<DIV>The lines run east and west, therefore, they are likely to cast a shadow
over the whole array when it does not miss them all. I am near positive
that the lines are significantly smaller than the sun ball. Likely if I
was looking straight at the sun through these wires, I would not see the
wires. We are considering microinverters. However, if we used a
single inverter, does an equal shadow on all panels make a difference? I
took my readings from a single point. However, the array will have
length. The only shading from other objects between 9am - 3pm will be in
December when this location will not see sun until 10:15am. During this
process of rising, it may fully expose some modules before others.
Therefore, microinverters would help. </DIV>
<DIV> </DIV>
<DIV>I like microinverters because they allow the system to expand and
contract. Therefore, you can undersize or oversize the actual load you are
trying to satisfy and take them away or add to them as required to match the
actual production with the actual consumption. However, there may be an
economy to installing a single inverter to match the whole array. </DIV>
<DIV> </DIV>
<DIV>Thanks for comments </DIV>
<DIV>Eli </DIV>
<DIV> </DIV></DIV></DIV>
<DIV>----- Original Message ----- </DIV>
<DIV>
<DIV>From: "Gordon Howell -- Howell Mayhew Engineering" <<A
href="mailto:ghowell@hme.ca">ghowell@hme.ca</A>></DIV>
<DIV>To: "Keith Winston" <<A
href="mailto:keith@earthsunenergy.com">keith@earthsunenergy.com</A>>; "Green
Building" <<A
href="mailto:greenbuilding@lists.bioenergylists.org">greenbuilding@lists.bioenergylists.org</A>></DIV>
<DIV>Sent: Monday, April 04, 2011 3:57 PM</DIV>
<DIV>Subject: [Greenbuilding] Electrical line shading of solar PV
modules</DIV></DIV>
<DIV><BR></DIV>> Thanks Keith:<BR>> <BR>> It depends significantly if
the height of the electrical line's <BR>> shadow on a cell is larger than the
diameter of the sun's disc (as <BR>> viewed from the cell) or not. If
the shadow is smaller then portions <BR>> of the beam radiation will not be
shaded and so it won't eliminate <BR>> the photon shower on the cell and thus
the current generated. It <BR>> thus is a "soft shadow" (not fully
shaded) and not a "hard <BR>> shadow". It will still effect the cell
and perhaps the module and <BR>> string, but not nearly as much as a
fully-shaded cell. I don't know <BR>> if I've ever seen a shadow from
an electrical line to be larger than <BR>> the sun's disc.<BR>> <BR>>
+Gordon<BR>> <BR>> <BR>> <BR>>>Date: Mon, 4 Apr 2011 11:43:05
-0400<BR>>>From: Keith Winston <<A
href="mailto:keith@earthsunenergy.com">keith@earthsunenergy.com</A>><BR>>>To:
Green Building <<A
href="mailto:greenbuilding@lists.bioenergylists.org">greenbuilding@lists.bioenergylists.org</A>><BR>>>Subject:
Re: [Greenbuilding] Electrical line shading of solar PV
modules<BR>>><BR>>>I'm not quite sure what you mean by "smaller than
the sun's disc"... larger<BR>>>power lines can cast distinct shadows. If
those align with an axis of the<BR>>>modules, then they may shade an
entire row of cells in a module, overcoming<BR>>>the ability of the bypass
diodes to "bypass" the shaded cells (most modules<BR>>>are, I believe,
still bypassed on a cell-by-cell basis, and are wired in<BR>>>series along
one of their axis). So I'll stand by my earlier comment that a<BR>>>power
line could very well create significant shading. But I agree with
the<BR>>>microinverter suggestion.<BR>>><BR>>>Keith<BR>>
<BR>> <BR>> _______________________________________________<BR>>
Greenbuilding mailing list<BR>> to Send a Message to the list, use the email
address<BR>> <A
href="mailto:Greenbuilding@bioenergylists.org">Greenbuilding@bioenergylists.org</A><BR>>
<BR>> to UNSUBSCRIBE or Change your List Settings use the web page<BR>> <A
href="http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org">http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org</A><BR>>
<BR>> <BR>></BODY></HTML>