Sustainable Building Operation Using Simulation - Low Energy Cooling for Sustainable Buildings - page 243

of six 90W p modules from Photowatt at a tilt angle of 25 ◦ . The module is made
of 72 polycrystalline silicon solar cells of 101.25 101.25mm, coated with sili-

con nitride anti reflection material. The system is coupled to a 500W Wurth Solergy
inverter.

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PV Module Characteristics

In the first step, six one-diode model parameters and the inverter characteristics had
to be determined using the data sheet information from the 90W Photowatt PW 1000
module and the Wurth Solergy WE 500 NWR inverter data.
The INSEL block pvdet1 was used to calculate the one-diode parameters from the
manufacturers' data. The values extracted from the Photowatt module data sheet are
summarized in Table 6.10 below. Using the extracted parameters for the simulation
model, the performance of the PV system was calculated, written to the server and
visualized.
The simulated performance was in general 15% higher than the measured perfor-
mance (see Figure 6.42). This means that the manufacturers' performance values do
not correspond to the module power of the system installed.
As a consequence, I - V curve measurements were carried out on the generator. A
Stella field tester was used at high irradiance levels of about 900Wm − 2 . A two-diode
curve fitting routine implemented as a block in INSEL (pvfit2) was then applied to all
three measured curves to extract the module parameters of the two-diode equation,
which are summarized in Table 6.8.

700

simulated power manufacturers, data

600

500

400

300

measured power

200

difference of simulated and measured power manufacturers, data

100

0

0 2000 4000 6000 8000 10 000

-100

Time in seconds from 12:00 / s

Figure 6.42 Measured and simulated power using the manufacturers' data sheet information