Solmetric PVA-1000S, User Manual

Page: 65 / 152

1 Getting Started
2-53
CAUTION Place the
I-V Measurement Unit
in the shade to reduce the likelihood of thermal
shutdown. Never place the I-V Measurement Unit on an asphalt driveway, on a solar
panel, or roof in direct sunlight.
Thermal Capacity of the PVA-1500xx
The thermal capacity of the PVA-1500xx is the number of I-V measurements that can be
made before the maximum allowable internal temperature is reached. Thermal capacity
decreases with higher Voc, higher outdoor ambient temperatures, and shorter wait time
between measurements. For example, if a PV plant with 16 strings per combiner box and
string Voc of 1300V is measured at the rate of one string every 17 seconds, followed by 5
minutes of no measurements (e.g. while moving to the next combiner box), then the
thermal capacity is more than 800 measurements at 25 deg C ambient temperature, and
250 measurements at 45 deg C ambient. After reaching the thermal capacity, every
minute of cooling (i.e. no measurements) increases the number of subsequent
measurements that will be allowed before thermal capacity will be reached again.
CAUTION The rigid grey enclosure of the I-V Measurement Unit (inside the soft case) gets very
hot. Do not touch.
Operating Under High-Temperature Conditions
The most demanding thermal conditions for the measurement unit are:
•
Hot day
•
No wind
•
No shade
•
High open circuit voltage
•
I-V sweeps taken in rapid sequence
If you expect these conditions, plan ahead to minimize temperature rise in the I-V
Measurement Unit. Shade the measurement unit from direct sunlight, elevate it above hot
surfaces, and allow more time between I-V sweeps.