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Amir,<br>
Thank you for the detailed email. We are looking into Type94 and
will let you know what we discover.<br>
Best,<br>
David<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 4/25/2014 00:12, Amir Nashed wrote:<br>
</div>
<blockquote
cite="mid:CAJ_vqRRutzK_yPh=Gt5JJXdoJAP3JTKHkPq9W1A7=PF2gb+4bQ@mail.gmail.com"
type="cite">
<div dir="ltr">Hello
<div><br>
</div>
<div>I previously sent 2 emails regarding potential bugs in
Type94a (PV 4 parameters model) and i can conclude the
following:</div>
<div><br>
</div>
<div><span style="font-size:13px;font-family:arial,sans-serif">1-</span><span
style="font-size:7pt;font-family:'Times New Roman'"> </span><span
style="font-size:13px;font-family:arial,sans-serif">The
equation used to calculate the IAM has a wrong sign in the
third term (should be -6.26E-6 rather than +6.26E-6) (this
error actually in some cases made the IAM to be larger than
1 which is incorrect as far as I know)</span><br>
</div>
<p style="font-family:arial,sans-serif;font-size:13px">2-<span
style="font-size:7pt;font-family:'Times New Roman'"> </span>The
last term in the equation used to calculate the IAM in the
manual is 1.4<span style="background-color:yellow">2</span>72E-8
while in the code is 1.472E-8</p>
<p style="font-family:arial,sans-serif;font-size:13px">3-<span
style="font-size:7pt;font-family:'Times New Roman'"> </span>Different
equations than those indicated in the manual are used to
calculate the effective angle of sky diffuse and ground
diffuse radiation</p>
<p style="font-family:arial,sans-serif;font-size:13px">4-<span
style="font-size:7pt;font-family:'Times New Roman'"> </span>The
variable SUNGND (surface ground diffuse radiation) is not
calculated anywhere in the code and it is not one of the
inputs </p>
<p style="font-family:arial,sans-serif;font-size:13px">5-<span
style="font-size:7pt;font-family:'Times New Roman'"> </span>The
reference efficiency EFFREF does not account for the module
surface area so I believe it should equal: Vm*Im/SUNR*Area
instead of Vm*Im/SUNR</p>
<p style="font-family:arial,sans-serif;font-size:13px">6-<span
style="font-size:7pt;font-family:'Times New Roman'"> </span>Equation
5.2.5-21 used to calculate the cell temperature in the manual
(page 74) I believe is incorrect [It should be
UL*(Tc-Ta)=TAU_Alpha*Gt*(1-Eff/TAU_Alpha) thus Tc=Ta+
TAU_Alpha*Gt*(1-Eff/TAU_Alpha)/UL ] (The equation is however
applied correctly in Type94 code script)</p>
<p style="font-family:arial,sans-serif;font-size:13px">7-
Finally, I found out why Type94a overestimates the IAM losses
(when the option is activated). This is because the SUN
variable, (Effective global tilted irradiance) is calculated
after multiplying each irradiance component IAM multiplier
(i.e. TADIR, TAGND, TADIFF) by TAMAX (TAU-ALPHA at normal
incidence), which i believe is incorrect as the IL at
reference conditions already includes the effect of TAU-ALPHA
at normal incidence. This error is however corrected when the
IAM mode is disabled where the SUN variable is not multiplied
by TAMAX</p>
<p style="font-family:arial,sans-serif;font-size:13px"><br>
</p>
<p style="font-family:arial,sans-serif;font-size:13px"> could
someone confirm the aforementioned bugs?</p>
<p style="font-family:arial,sans-serif;font-size:13px">
<br>
</p>
<p style="font-family:arial,sans-serif;font-size:13px">Thank you</p>
<p style="font-family:arial,sans-serif;font-size:13px">Regards,</p>
<p style="font-family:arial,sans-serif;font-size:13px">Amir</p>
</div>
<br>
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<pre class="moz-signature" cols="72">--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
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