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<div id="signature">Kirk,</div>
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<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>
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<div>You have to design for winter offgrid if the location is worth it. Or, alot of hours on a genset.</div>
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<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 />
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<pre><strong><span style="font-size: small;">Dave Angelini Offgrid Solar
"we go where powerlines don't"
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e-mail <a href="mailto:offgridsolar@sti.net">offgridsolar@sti.net</a>
text 209 813 0060</span></strong></pre>
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<p id="reply-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">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" target="_blank" rel="noopener noreferrer">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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