This work centered on the Tucson Solar Test Yard, a utility-owned photovoltaic facility built to study how different solar panel technologies perform in Tucson’s climate. After the yard had been constructed but the research was left largely dormant, Dr. Alex Cronin organized a partnership that turned it into a live teaching and research environment for University of Arizona students.
My role involved helping document the yard, calibrate instrumentation, support data collection, and translate technical work into a form that could be shared with both technical and public audiences. That meant not only understanding the science and hardware, but also building repeatable processes for measurement and explaining what the data meant.
A real-world solar research environment
The scale of the test yard made it far more than a classroom exercise. The site included about 650 photovoltaic panels arranged into 22 separate systems, with roughly 90 kW peak power to the grid and an estimated total cost of about $3 million including upkeep. Each string functioned as a complete monitored system with panels, a DC sensors box, an AC power meter, an inverter, a thermocouple, and a data logger card.
- 650 photovoltaic panels across 22 systems
- Approximately 90 kW peak power to grid
- Multiple inverter types including Xantrex, Fronius, and Beacon Power
- Funding support from TEP, AzRISE, and NREL
From instrumentation to long-term performance analysis
The immediate goal was to install, verify, and calibrate equipment capable of monitoring DC voltage, DC current, AC power, and temperature across the yard. The longer-term goal was broader: understand photovoltaic performance in Tucson, study how variables such as temperature and fill factor affected output, and create a platform for testing new solar technologies.
In practice, this project sat at the intersection of physics, electrical systems, and data analysis. It required careful hands-on work, but it also required enough analytical discipline to ensure the resulting measurements were trustworthy.
How the yard was monitored
Each photovoltaic string fed through a DC sensors box and inverter into the grid, while a data acquisition layer continuously tracked key operating values. The monitoring system combined electrical measurement hardware with a local network and web interface, making it possible to collect operational data at scale.
Measured inputs
- DC voltage
- DC current
- AC power output
- Temperature via thermocouples
Acquisition approach
- Continuous logger monitoring across strings
- AC meters configured to record energy delivery to the grid
- Data collected every second and averaged every minute
- Local network and web interface for access to readings
Where the rigor lived
A major part of the work involved calibration. Because each hall probe and voltage divider behaved slightly differently, every string had to be calibrated separately. That mattered: even small hardware changes could materially alter calibration equations, and without recalibration the reported data could become misleading.
DC voltage calibration used an external voltage supply and digital multimeter readings to build linear fits between logger values and true panel voltage. DC current calibration used a wrapped-wire setup through hall probes to generate known currents, then transformed logger readings into total system current while accounting for parallel string geometry. Temperature measurements were standardized through Omega devices configured over a fixed Celsius range.
- Each string calibrated independently
- Linear-fit equations used to convert digital logger readings to physical values
- Recalibration required after hardware changes
- Calibration quality directly affected downstream efficiency and performance analysis
Comparing photovoltaic approaches
One of the most interesting aspects of the yard was the range of photovoltaic technologies represented. The project included systems from multiple manufacturers and at least four primary panel categories, creating a practical test bed for comparing performance, cost, and efficiency under the same local environmental conditions.
- Polycrystalline silicon
- Thin-film silicon
- CIGS (Copper Indium Gallium Selenide)
- Monocrystalline silicon
This made the site valuable not just for operating a solar installation, but for evaluating how different design choices translated into real-world energy production in desert conditions.
Technical work and technical communication
This project pushed me to operate in two modes at once. On one side was the hands-on engineering work: instrumentation, calibration, measurement discipline, and understanding how the hardware actually behaved. On the other was communication: documenting procedures, presenting the research, and helping make the work understandable to different audiences.
- Helped document the solar yard and its instrumentation
- Supported calibration procedures for voltage, current, and temperature monitoring
- Worked with data acquisition concepts and performance comparisons
- Contributed to presentation and public-facing explanation of the research
What this project taught me
- Good data depends on disciplined calibration, not just measurement
- Physical systems rarely behave identically, even when they appear similar on paper
- Technical work becomes more valuable when it is documented clearly
- Research environments require both analytical thinking and practical caution
- Public-facing science communication is a skill in its own right
Why the work mattered
The yard was designed not only to study current photovoltaic systems, but to support future research into irradiance measurement, panel cleaning effects, power storage, and smarter inverter technologies capable of responding to intermittent generation. That broader vision is what made the project compelling: it was a chance to contribute to a live platform for applied energy research, not just a static academic exercise.
This page is based on the original student manual and presentation materials created in 2009.