Procurement lists for utility-scale solar projects can include hundreds of components. Amid the complexity, solar irradiance sensors — also known as pyranometers — are often chosen based on familiarity. Some users tend to default to models they know and trust, without realizing that equivalent alternatives exist — options that meet the same technical requirements but may offer advantages in terms of cost or ease of integration.
This small sensor plays a big role in PV site benchmarking, and performance validation.
Most EPCs understand that both distributed generation and utility-scale projects require a Class A sensor, but they often overlook the nuances of sensor selection. As expectations for performance monitoring and long-term reliability continue to rise, this seemingly minor component plays a critical role in how site performance is measured, verified and optimized. In short, it’s not just another box to tick.
4 things to look for in a pyranometer
When selecting a Class A sensor for solar projects, the technical spec sheet is only part of the story. The realities of field installation, commissioning and ongoing operations all impact project outcomes and the bottom line. Here are four key factors to keep in mind:
- Product availability and lead time
EPCs work under strict timelines, where delays can result in costly penalties. That makes reliable product availability essential. Look for suppliers with strong inventory management systems — ideally using algorithm-based forecasting — and ask about their ability to handle urgent replacements or ad hoc shipments. Weeks-long delays due to supply chain issues can quickly derail schedules and budgets. - Ease of installation
Incorrect installation, whether due to wiring errors, poor leveling or improper mounting, can compromise data quality and lead to expensive truck rolls for rework. Getting it right the first time is critical. Select sensors designed for intuitive setup, with features like built-in tilt and level indicators, pre-assembled cables and multilingual installation guides. A well-thought-out design enables even less-experienced crews to install sensors correctly and efficiently, reducing the risk of errors that only become apparent during commissioning and testing. - Responsive, expert support
Commissioning is a high-pressure phase, and support needs to be quick and competent. Look for suppliers with experienced, in-country technical staff who understand field conditions. The ability to connect directly with knowledgeable experts without navigating a slow or complex support structure can prevent costly delays. Ask if they’ve supported commissioning emergencies before and what real-time help is available. - Total value
Sensor price is only part of the equation. Factor in the full cost of installation, commissioning and support. Time savings from easier installs, rapid replacements and responsive service can outweigh minor differences in unit cost. Consider all-in-one sensor models that simplify procurement and deployment, and inquire about volume pricing for multi-site or large-scale projects.
Key questions to ask your sensor supplier
Most suppliers offer multiple Class A pyranometer models. After sharing the details of your project, climate, system architecture and data goals, ask for guidance in selecting the most suitable sensor for your specific needs.
A technician installs two Class A pyranometers on site.
At a minimum, ensure the sensor solution meets ISO 9060:2018 and IEC 61724-1:2021 standards. From there, look more closely at factors such as:
- Sensor response time
Faster sensors can better capture rapid irradiance fluctuations, improving data granularity for high-resolution analysis. - Anti-dew and frost mitigation
Moisture and frost can cause signal loss or measurement error. While many sensors use active heating and ventilation to combat this, those solutions also increase power consumption, sometimes significantly. Ask whether passive or low-power approaches are available that still meet performance goals. - Surge protection
Sites are often exposed to electrical noise or transient voltages. Integrated surge protection can help safeguard your measurement chain, particularly in areas prone to lightning strikes. - Offset errors (especially Offset C)
Look at how the sensor performs under low irradiance or stable radiation conditions. Offset C can impact accuracy during cloudy or early-morning conditions, an often-overlooked but important factor. - Power consumption
Total energy draw, including heaters, fans and communication, can affect backup power system sizing. This is especially important for remote or off-grid systems.
Beyond specifications, some of the most impactful considerations won’t appear in a datasheet, like ease of installation. If you’ve dealt with issues in the past related to wiring, mounting or leveling, ask how the manufacturer supports a smoother installation process. Do they offer built-in leveling tools, pre-terminated cables or multilingual guides? Do they provide training resources or commissioning checklists?
Badly installed sensors can compromise data and trigger costly truck rolls, especially if issues aren’t detected until commissioning. It pays to get it right the first time.
Choosing hastily costs time and money
Accurately selecting and installing the appropriate pyranometer is a must in accurately understanding site performance.
Selecting the wrong sensor or rushing the decision can lead to a range of downstream issues. Poor data quality, installation errors and communication problems can all result in unexpected costs for you and your client. Mistakes in wiring, mounting or leveling — especially by less-experienced crews — can cause signal interference, excessive noise or complete data gaps. Misalignment and configuration issues are also common, potentially compromising the performance of the entire monitoring system.
While developers typically specify the number and general location of sensors and weather stations, they often define a designated area rather than an exact mounting point. This leaves EPCs and field crews to make judgment calls based on terrain, array layout and practical installation constraints. Without adequate support, these decisions can lead to subpar measurements that undermine long-term performance analysis.
A knowledgeable and responsive supplier plays a vital role in helping teams determine the best placement, integration approach and installation practices. Getting these details right from the start helps prevent costly rework, shortens deployment timelines and ensures accurate, reliable data throughout the system’s life.
The ultimate goal: A reliable and durable sensor
While reliable supply, ease of installation, and responsive customer support are essential when selecting a sensor, EPCs should also prioritize long-term reliability and durability. For projects expected to operate for 25 years or more, sensor performance and supplier consistency can have lasting impacts on both data quality and client relationships.
When building long-term partnerships, focus on factors that reflect the quality and dependability of both the sensor and the supplier throughout the full project lifecycle:
- Sensor calibration frequency and long-term stability – When feasible, sensors that maintain accuracy with longer calibration intervals can help reduce service costs and disruptions. Even when regular recalibration is required, consistent performance between intervals is an important indicator of quality.
- Supplier accreditations and certifications – Look for recognized standards such as ISO, IEC, ASTM and IMEI to confirm manufacturing quality and compliance.
- Responsiveness to repairs and replacements – Timely support is critical during commissioning and troubleshooting. A supplier’s ability to quickly resolve issues can help keep projects on schedule.
- Proven manufacturing track record – A history of producing solar irradiance sensors for utility-scale applications shows the supplier understands the demands of long-term field deployment.
Selecting a Class A sensor is more than a technical decision. It’s also a strategic choice — one that mitigates risk, streamlines maintenance and helps ensure reliable performance from day one through decommissioning. Staying with a trusted supplier over time further strengthens project reliability and operational continuity.
Although pyranometers represent a small fraction of the system budget, they play a central role in measurement, benchmarking, and performance validation. Making a careful, informed choice helps lay the groundwork for a successful project, and a successful partnership.
With over two decades of experience in meteorological and irradiance instrumentation, Wayne Burnett serves as the CTO of EKO Instruments USA, where he supports advanced measurement solutions for the renewable energy sector.
