[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [TRNSYS-users] type 94a question
Kostas,
I can think of a few things that might account for the difference. First
(and the simplest) is that Type94 does not account for any wiring losses
between the PV modules or between the array and the inverters (where the
actual power produced is usually measured). Those wiring losses can be
significant, especially for high current (low voltage) applications
(P=I^2*Rwire). Second, actual PV panels have a bit of variability in them.
The specification sheet is usually an idealized average that was generated
at a test facility. I have seen PV panels whose actual current-voltage
characteristic was as much as 10% different from the spec sheet. When a
number of PV panels are combined in series and in parallel to form an
array, the weaker panels dictate the performance of array since the voltage
drop over each parallel branch must be the same. Lastly, localized shading
effects can have an important impact on array performance (again, not
directly reflected in Type94). The problem is that the actual power output
reduction of a shaded PV is not a linear function of the fraction of the PV
that is shaded. I hope that helps to explain some of the potential
differences between the simulated and expected results.
Kind regards
David
At 09:14 3/29/2007, =?ISO-8859-7?B?yv7z9OHyIM/x5O/17PDv5tzt5/I=?= wrote:
I noticed that the values of the output of the Type94a are much grater
than the real one. The efficiency coefficient of the current PV is 274 [W]
/(1000[W/m2]*2.24[m2])=0.122, while the Type94 gives 0.16 while the
radiation is near the reference conditions...
The problem that I have noticed in practice is that I tried to simulate a
100 kW PV station. The price of the PV kW in Greece is 0.47 ¤/kW and the
mean gain (¤) of a 100 kW PV for a year is about 55.000 - 60.000 ¤. The
TRNSYS gives a value of 100.000¤ per year. So since the price is the same,
the problem is that it gives much more output (kW)
Any Ideas ?
Ordoumpozanis Kostas
Kozani, 29/03/2007
Greece
Content-Type: application/zip; name="bathmos apodosis.zip"
X-Attachment-Id: f_ezvae3hx
Content-Disposition: attachment; filename="bathmos apodosis.zip"
_______________________________________________
TRNSYS-users mailing list
TRNSYS-users@engr.wisc.edu
https://www.cae.wisc.edu/mailman/listinfo/trnsys-users
****************************************************************************************
Thermal Energy System Specialists (TESS), LLC
David BRADLEY 2916 Marketplace Drive - Suite 104
Partner Madison, WI 53719
Phone: (608) 274-2577 USA
Fax: (608) 278-1475
E-mail: bradley@tess-inc.com
Web Pages: http://www.tess-inc.com and http://www.trnsys.com
"Providing software solutions for today's energy engineering projects"
****************************************************************************************