Fluke IRR1 Solar Irradiance Meter

Works as it should

I will use the meter to check the performance of solar PV projects I develop.

Great for setting slope, azimuth and checking module output.I gave it 4 stars because if you want Fahrenheit you have to change it every time you turn on the meter and the initial setup for the compass is a pain. Worse, when you change the batteries you have to do it again!It's well made, it's Fluke, the industry standard. I have 40 year old Fluke meters that still work perfectly and are still accurate. I see people on YouTube using the same meters so I'm not the only person who still runs them.

good seller

We purchased this meter through my company’s Amazon account, which is why I’m not a verified buyer. However, I felt it was important to write this review because the issue with this device is so severe that it needs to be highlighted.I conduct Solar PV inspections regularly—3 to 5 per month in the winter and 10 to 12+ per month in the summer. For years, I had been using an Amprobe Solar 100, which, while functional, had its drawbacks. The biggest issue was the external sensor on a dongle, which made it cumbersome to use when trying to take measurements while simultaneously photographing readings. Additionally, the screen had begun to degrade, making it difficult to use in bright sunlight.When we decided to upgrade, the Fluke IRR1-SOL seemed like a logical step despite being nearly double the price of the Amprobe ($180 vs. ~$370). Fluke is a company known for producing high-quality, reliable, and accurate test instruments, and this meter offered two additional features that the Amprobe lacked—panel pitch measurement and temperature sensing—both of which are critical for tracking systems and quality inspections.At first glance, the build quality of the Fluke meter seemed excellent—rugged as expected, with a rubberized back that helps it stay in place on tilted panels even in cold weather. Unfortunately, that’s where the positives end because this device has a critical design flaw that fundamentally undermines its ability to provide accurate irradiance readings.The Irradiance Sensor Design is Fatally FlawedFluke has inexplicably designed this meter with a raised plastic housing around the irradiance sensor, which casts a shadow over the sensor unless the meter is positioned in an absolutely perfect alignment with the sun. This is an enormous problem.As any experienced solar professional knows, field conditions are never perfect. The angle of the panel, sun position, and the necessary placement of the meter mean that in real-world usage, this shadowing effect makes it impossible to get consistently accurate readings. I have to tilt the meter in various directions just to reduce the shadow effect, and even then, readings can be off by several hundred W/m²!Example:Fluke meter placed flat on the panel: 689 W/m² (visible shadow from its own casing).Meter tilted slightly to avoid shadow: 848 W/m².That’s a 159 W/m² difference caused entirely by the meter’s own flawed design! This is completely unacceptable for a device designed to provide critical measurement data for solar performance assessments.The Temperature Sensor is Far Less Accurate Than AdvertisedTo make matters worse, the temperature sensor’s advertised accuracy is misleading. The included documentation revealed that at lower temperatures (14°F to -22°F), the accuracy drops from ±4°F to ±9°F—more than double the stated tolerance. This kind of inaccuracy is something I’d expect from a cheap, sub-$50 generic meter, not a Fluke product that commands a premium price.Fluke Should Be Embarrassed by This ProductFluke has a long-standing reputation for precision, durability, and reliability in test instruments. That’s why it is absolutely shocking that such a glaring design oversight made it past quality control. The fact that the sensor housing itself interferes with accurate measurements is a fundamental flaw that should never have made it into production.For a company that manufactures $25,000+ electrical testers, it’s hard to reconcile how this device—something that should be relatively simple to get right—was released in this state.I’m giving this product two stars only because it technically works if you’re willing to wrestle with its flaws, but it does not meet the standards expected of a Fluke instrument. At this price point, let alone from this brand, this level of inaccuracy and poor design is simply unacceptable.Avoid this meter unless Fluke addresses these critical issues.