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### Outdoor Monitoring and High Voltage Bias Testing of Thin Film Photovoltaic Modules

####### NREL, UCF/FSEC Account \# 2012 8071 

> **Year 1 Quarter 4 Report, FSEC-CR 1499-05**

**Feb 01, 2005**

######### **Introduction**

The Outdoor monitoring and High Voltage Bias Testing of Thin Film
Photovoltaic Modules has been undertaken through the project funded by
NREL for a period of three years. This is the Year 1, Quarter 4 Report,
FSEC-CR 1499-05. This report is for the period July 1, 2004 -- Sep 30,
2004. The report contains the necessary steps taken to prevent the
modules from any damages and the effects of the hurricanes, data, and
visual inspection results of the modules.

This work consists of the study of outdoor testing and monitoring of
photovoltaic (PV) thin film modules fabricated by First Solar
(Glass/CdTe/Glass), Shell Solar (Glass/CIS/Glass), United Solar (a-Si on
flexible substrate), Energy Photovoltaics (Glass/ a-Si/Glass), and
Global Solar (CIS on flexible stainless steel foil substrate) with
additional 2 crystalline silicon modules in hot and humid climate of
Florida.

######### **Outdoor Monitoring and High Voltage Bias Testing of Thin Films PV Modules Data Acquisition** 

######### 

As mentioned in the earlier report, thin-film PV modules from the
following US PV Manufacturers have been installed on the Florida Solar
Energy Center (FSEC) high voltage test setup: (6+6+2)-First Solar
(CdTe), (24+24)-Shell Solar (CIS), (20+20)-Uni-Solar (a-Si:H) and (9+9)
Energy Photovoltaics (a-Si).

These modules are connected in series so as to reach a maximum open
circuit voltage, Voc of approaching +600V and --600V. The modules are
connected across a load consisting of several resistors to provide an
operational point near the maximum power point. A small resistor has
been connected in series with the resistive load, across which
measurements are carried out. Each array voltage output, solar
irradiance, along with ambient parameters such as ambient temperature,
back of the module temperature at two locations, relative humidity, UV
index and wind speed are being monitored on daily basis. This report
provides the data collected from July -- Sep 30, 2004 for all the arrays
in the standard format suggested by NREL.

**Hurricane Report:**

Florida was hit hard by the following five hurricanes in the year 2004:
Bonnie, Charley Frances, Ivan and Jeanne. Cocoa had no effect due to
Hurricane Bonnie and Ivan. The FSEC Test Site at Cocoa, FL experienced
small effect due to Hurricane Charley. On the other hand, the Hurricanes
Frances and Hurricane Jeanne caused severe damage in Cocoa.

**Hurricane Charley:**

The first predicted movement path of the hurricane Charley was to hit
Florida coast near Tampa, move northwest of Orlando and move out of
Florida through Jacksonville. It was announced on Friday, Aug 13, 2004
at 12.00 PM that the hurricane had changed its path as compared to what
had been predicted earlier. The new path was to hit Punta Gorda, move
through Orlando and move out of Florida through Daytona into the
Atlantic Ocean. Since FSEC was near but not within the direct path of
the Hurricane, all the modules were tied to channels with nylon ropes to
prevent them from flying off (Figure 1). The Charley Hurricane hit the
Florida West Coast on Aug 13, 2004. At landfall in Port Charlotte and
Punta Gorda the wind speed was in the range of 145-150 mph making it a
category 4 hurricane. It passed through downtown Orlando with a speed of
110 mph. The wind speed in the Cocoa area was in the range of 50-60 mph
with wind gusts of over 74 mph.

***Precautions:***

![](media/image2.png){width="5.999305555555556in"
height="1.117361111111111in"} All the module columns were tied to the
channels with nylon rope to prevent them from flying due to breakage of
the mounting structure as shown in the figure 1.

Figure 1. Each column of the module arrays tied with rope to the
channels.

***Effects:***

After the hurricane passed through, a visual inspection was carried out
on Aug 14, 2004 at 12.00 PM. It was found that all modules were safe but
the southwest side of the fence had partially collapsed as shown in the
figure 2. However, on Aug 16, 2004 it was found that four EPV modules
were broken as shown in the figure 3-4. Since the modules are frameless
it was concluded that they had broken due to stresses from the ropes
used for tying them to the mounting channels. It is probable, that
microcracks that were formed grew and led to complete cracking.

![](media/image3.png){width="3.9993055555555554in" height="1.5in"}

Figure 2. Collapsed fence.

![](media/image4.png){width="4.0in" height="1.5in"}

Figure 3. Typical crack in the EPV module.

![](media/image5.png){width="3.0in" height="1.5in"}

Figure 4. Crack in the EPV module.

**Hurricane Frances:**

The predicted path of Hurricane Frances was to hit the East Florida
Coast somewhere between Melbourne and West Palm Beach on Sep 4 or Sep 5,
2004. This time the Brevard County was directly under the path of
Hurricane Frances. The Florida Solar Energy Center was closed during Sep
2-6, 2004. The Brevard County officials also issued mandatory evacuation
orders. Hurricane Frances was as big as the state of Texas, twice the
size of Charley and moving slowly with heavy gusts. The hurricane hit
the Florida East Coast in the early hours of Sep 5, 2004. At the
landfall in Sewall's Point 35 miles north of West Palm Beach the wind
speed was in the range of 105-110 mph. The hurricane battered through
the Florida Peninsula for up to 36 hours over the weekend before it
again passed into the Gulf of Mexico.

***Precautions:***

Since the size of the hurricane was huge and it was moving slowly with
heavy gusts, it was decided to remove all the field-deployed modules.
All the modules were uninstalled (Fig. 5) and moved to a safe location
within the center.

***Effects:***

A brief inspection of the mounting structure was made on Sep 6, 2004 at
noon. No damages had occurred. As the Hurricane Frances was passing away
from Florida another Hurricane Ivan had already started in the Atlantic
Ocean and it was almost following the path of Hurricane Charley. Hence
it was decided not install the modules back until a clear picture of the
path of Hurricane Ivan was available. On Monday Sep 13, 2004 the
projected path for Hurricane Ivan was far away from the center. Hence it
was decided to re-install the modules. The modules were re-installed
during Sept. 13-20, 2004.

![](media/image6.png){width="6.497916666666667in"
height="2.3208333333333333in"}

Fig. 5: Modules Uninstalled

**Hurricane Jeanne:**

The predicted path of Hurricane Jeanne was to hit the east coast of
Florida on Sep 25, 2004. The Brevard County was directly in the path of
the hurricane. Again, mandatory evacuation orders were issued for the
Brevard County. The western edge of the outer eyewall made landfall at
Stuart south of Fort Pierce on Sep 25, 2004 at 11.50 pm EST. The
hurricane was of category 3 with sustained winds up to 115 mph at the
landfall.

***Precautions:***

All the modules were uninstalled and moved to a safe location in the
center. All the junction boxes were tied to the mounting structure.

***Effects:***

A brief inspection was carried out on Sep 27, 2005. No damage was
reported to the mounting structure and the junction boxes.

**Reinstallation:**

The modules reinstallation process was started on Sep 27, 2004. All the
modules were reinstalled by Sep 30, 2004.

**Data Collection:**

The First Solar voltage measuring resistor burnt. This led to the
burning of the multiplexer (Fig 6). The data was collected for the
initial 26 days of July 2004. No data is available from 1826 Hrs, July
19, 2004 to 1654 Hrs, July 22, 2004. The datalogger was shut off. On
July 27, 2004 the multiplexer burnt and hence no data is available for
the remaining month.

This was followed by frequent threats and actual hits by hurricanes in
the Central Florida region. As described earlier, the modules were
uninstalled and installed back twice. During the intermediate periods,
it was not possible to make complete connections and verify them to
acquire the data. Therefore, no data was available for the remaining
quarter.

![](media/image7.png){width="4.000694444444444in"
height="1.8770833333333334in"}

# Fig. 6. Burnt Multiplexer

# 

# High Voltage (HV) Bias Testing

The study of leakage currents in high-voltage biased thin film
photovoltaic (PV) modules fabricated by First Solar (CdTe), Shell Solar
(CIS) and Uni-Solar (a-Si:H) has also been undertaken through this
project for a period of three years. FSEC high voltage test bed
consisting of two modules from each manufacturer, First Solar (CdTe),
Shell Solar (CIS) and Uni-Solar (a-Si:H) were installed at +600 V and
--600 V respectively.

All the modules were uninstalled during Hurricane Frances and Hurricane
Jeanne and moved to safer location. Inspections were carried out and the
mounting structure on the low bay area of the FSEC building was safe.
All the modules were reinstalled by Sep 30, 2004.

**Planned Activities for Year 2, Quarter 1:**

1)  Restore all the electrical connections and also add some new
    components to the electrical circuit to measure some additional
    parameters.

2)  Install the remaining modules of different companies as controls.

3)  Make changes in the websites to display all the additional
    parameters.

4)  Launch new website for data of Energy Photovoltaics (EPV) and Global
    Solar modules.