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<div>Dave,</div><div><br></div><div> The paper reference was at the
bottom of my original post (1), but a quick summary of what they
recommended was exactly what you mentioned - Have two axis trackers "go
horizontal" during heavy overcast instead of continuing to track the sun
to improve production!</div><div><br></div><div> I'm familiar with
the general tradeoffs for off-grid in terms of array oversizing,
generator usage, and load shedding: We have had past customers that
have made it work for them, and others that couldn't and ultimately
decided to get a grid connection!</div><div><br></div><div>Cheers,</div><div><br></div><div>Kirk Bailey</div><div><a href="mailto:kirk@abundantsolar.com" target="_blank">kirk@abundantsolar.com</a></div>
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<div id="m_6141406745729661135signature">Kirk,</div>
<div> </div>
<div>Can you reference your paper on this? So many variables and each location will be different. Most dual axis </div>
<div>trackers can always be left flat or any angle so that does not make sense to me.</div>
<div> </div>
<div>You have to design for winter offgrid if the location is worth it. Or, alot of hours on a genset.</div>
<div> </div>
<div>Super large arrays in your area will help give you more days/hours before you need the iron genoa.</div>
<div>You have to decide if it is worth the money. The home has to have the ability to shed some loads also.<br>
<pre> </pre>
<pre><b><span style="font-size:small">Dave Angelini Offgrid Solar
"we go where powerlines don't"
<a href="http://members.sti.net/offgridsolar/" rel="noopener" target="_blank"> </a><a style="color:blue;font-size:11px;font-family:'Lucida Grande',Verdana,Arial,Helvetica,sans-serif;font-weight:400;background-color:#ffffff" href="https://offgridsolar1.com/" rel="noopener noreferrer" target="_blank"><span style="font-size:12pt">https://offgridsolar1.com/</span></a><a href="http://members.sti.net/offgridsolar/" rel="noopener" target="_blank"> </a>
e-mail <a href="mailto:offgridsolar@sti.net" target="_blank">offgridsolar@sti.net</a>
text 209 813 0060</span></b></pre>
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<p id="m_6141406745729661135reply-intro">On 2023-10-25 3:46 pm, Kirk Bailey via RE-wrenches wrote:</p>
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<p style="line-height:100%;margin-bottom:0in;background:transparent"><span style="font-family:Times New Roman,serif"><span style="font-size:medium">Hi All!</span></span></p>
<p style="line-height:100%;margin-bottom:0in;background:transparent"><span style="font-family:Times New Roman,serif"><span style="font-size:medium"> </span></span></p>
<p style="line-height:100%;margin-bottom:0in;background:transparent"><span style="font-family:Times New Roman,serif"><span style="font-size:medium">We don't do a lot of pure off-grid systems and I recently ran across something I wanted to run by folks with more experience in this area: Optimal array tilt for our very cloudy PNW winters!</span></span></p>
<p style="line-height:100%;margin-bottom:0in;background:transparent"><span style="font-family:Times New Roman,serif"><span style="font-size:medium">My understanding has always been that latitude plus 10-15 degrees was the best tilt to address our winter energy shortage. However a paper I recently read (1), makes a compelling case for a much shallower tilt in situations where the cloud cover is so heavy that "diffuse" solar radiation is all that makes it through. They indicate that under those conditions a horizontal array will produce significantly more energy than even a two-axis tracker!</span></span></p>
<p style="line-height:100%;margin-bottom:0in;background:transparent"><span style="font-family:Times New Roman,serif"><span style="font-size:medium">Given that the challenge in our off-grid setups always seems to be making it through the really cloudy stretches, and that there is usually enough energy the rest of the time, should we be installing off-grid arrays at a shallower angle?</span></span></p>
<p style="line-height:100%;margin-bottom:0in;background:transparent"><span style="font-family:Times New Roman,serif"><span style="font-size:medium">Anyone tried this?</span></span></p>
<p style="line-height:100%;margin-bottom:0in;background:transparent"> </p>
<p style="line-height:100%;margin-bottom:0in;background:transparent"><span style="font-family:Times New Roman,serif"><span style="font-size:medium">Kirk Bailey</span></span></p>
<p style="line-height:100%;margin-bottom:0in;background:transparent"><span style="font-family:Times New Roman,serif"><span style="font-size:medium"><a href="mailto:kirk@abundantsolar.com" rel="noreferrer" target="_blank">kirk@abundantsolar.com</a></span></span></p>
<p style="line-height:100%;margin-bottom:0in;background:transparent"><span style="font-family:Times New Roman,serif"><span style="font-size:medium"><a href="http://www.abundantsolar.com" rel="noopener noreferrer" target="_blank">www.abundantsolar.com</a></span></span></p>
<p style="line-height:100%;margin-bottom:0in;background:transparent"> </p>
<p style="line-height:100%;margin-bottom:0in;background:transparent"><span style="font-family:Times New Roman,serif"><span style="font-size:medium">(1) Kelly, N.A., Gibson, T.L, 2011, Increasing the solar photovoltaic energy capture on sunny and cloudy days. Solar Energy 85, 111-125.</span></span></p>
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