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<p>I hadn't considered the snow melt advantage, which would
definitely help at this location, 4600' in the Sierra. And yes,
the reflection off of snow has always been a good boost in output
in this area, with the lower edge of the array ~18 feet off the
ground and a lower sun angle reflecting off snow in the winter I'm
assuming this is close to ideal for bi-facial. </p>
<p>We'll have to check to see if bi-facial is as strong for snow
load. It's the backside gain in the summer that's stumping us.
(white) concrete is too energy intensive, whatever is out in front
of the array will get driven on occasionally (it's more for
storage than daily driving), its red 3/4" crushed gravel now.</p>
<p>Appreciate the feedback, Gotta love a challenge.</p>
<p>Bill</p>
<pre class="moz-signature" cols="72">Feather River Solar Electric
Bill Battagin, owner
4291 Nelson St. (Shipping)
5575 Genesee Rd. (USPS, UPS)
Taylorsville, CA 95983
530-284-7849, 258-1641(cell)
CA. C10 Lic # 874049
Solar Powered since 1982
Home of the Sunny Side Up</pre>
<div class="moz-cite-prefix">On 12/21/2025 12:49 PM, Zeke Yewdall
via RE-wrenches wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CANC8fmQFdT3rdyZzcK66Wd_W69ZPm6URwvPMW8mNPcEk1Q1shA@mail.gmail.com">
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<div>We've been using bifacial modules for ground mounts in
Colorado this last year and they seem to be doing very well.
No hard data with a side by side comparison with a regular
module, but it seems that they generate better. We use snow
as our reflection surface. I've also heard anecdotally that
they are good in cloudy conditions in the pacific northwest
where you aren't collecting much direct beam radiation, but
again, I don't curently have side by side monitoring data.
PVwatts claims a 5 to 10% increase in most climates, and less
sensitivity to exact orientation, which could also help with
off grid sites. It also seems like the dark backside heats up
a little faster on grounmounts and melts snow and ice off just
a little faster than regular modules.</div>
<div><br>
</div>
<div>As far as backside shading goes. The back side behaves just
like the front side from small hard shadows (like from
racking). A significant drop in production. But diffuse
light, which is almost always what the back side is receiving,
should be less affected by racking shading -- but I still
think it would make sense to try to reduce racking shading of
the back side.</div>
<div><br>
</div>
<div>The biggest thing that concerns me about bifacial modules
is that most of them are not tempered glass. Two 2mm layers
of heat strengthened glass is supposed to be stiffer than one
layer of 3.2mm tempered glass, but still less impact
resistance if you are in any potential hail area in the 1" to
2" range (higher than 2" is liable to break even the tempered
glass modules anyway). Other than that, I don't see any
downsides, as they are usually cheaper per watt than regular
modules too. A lot of people were using them on flush roof
mounts because of the cheaper price, though you get zero
benefit from the bifacial aspect there.</div>
<div><br>
</div>
<div>Z</div>
<br>
<span class="gmail_signature_prefix">-- </span><br>
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data-smartmail="gmail_signature">
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<div>
<div dir="ltr">Zeke Yewdall
<div>PV Engineer</div>
<div>NABCEP #031508-89</div>
<div><a href="mailto:zeke@darkforestsolar.com"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">zeke@darkforestsolar.com</a></div>
<div>303-523-3592</div>
</div>
</div>
</div>
</div>
</div>
<br>
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