Fluke — IRR1-SOL / IRR2-BT solar irradiance meter
A hand-held irradiance, temperature, tilt and compass meter for PV surveys and commissioning — accuracy of ±(5% + 5 digits), and a compass referenced to magnetic north.
Reviewed 6 October 2026
To judge whether a plant is producing what it should, you need to know how much sun was falling on it. Fluke’s IRR1-SOL and IRR2-BT are hand-held meters that measure irradiance (50 to 1,400 W/m², 1 W/m² resolution), temperature (built in or via an external suction-mount probe), roof or panel tilt (±90°) and compass direction. The sheet says they are designed to help meet IEC 62446-1 requirements for testing and documenting PV systems.
The IRR2-BT adds Bluetooth, a 64 kB memory (6,400 records, about 17 hours of recording) and a mounting bracket; it is built to send readings to Fluke’s SMFT-1000 PV analyzer for I-V curve work. The IRR1-SOL is the simpler version without the wireless module.
Both are small (150 × 80 × 35 mm, 231 g), run on four AA batteries for about 50 hours, and are rated IP40 — an indoor-grade rating for a tool you will hold in the sun, so treat it with care on site.
For Installers & Engineers
Deeper technical detail beyond the homeowner-facing summary above.
Stated irradiance accuracy is ±(5% + 5 digits). Our arithmetic: at 1,000 W/m² that is about ±55 W/m², so a reading can be off by around 5.5%. That is acceptable for a site survey and a sanity check, but a thin margin for judging a performance ratio within a few percent. HT Instruments quotes ±3.0% for its separate reference cell.
The compass is accurate to ±7° and the sheet states results are referred to magnetic north. For design azimuth you want true north; the difference between the two (magnetic declination) is small across much of India but not zero, and nearby steel structures disturb a magnetic compass.
Inclination is accurate to ±1.5° within −50° to +50°, with wider tolerances toward ±90° — good enough to document tilt on a roof.
The sheet’s EMC section states the meters are Class A (CISPR 11) equipment “not intended for use in residential environments” — a note for anyone planning to use them for home installations.
The Scorecard
How we scoreStandards & Safety Compliance
Supports documentation for IEC 62446-1 and lists EMC compliance, but the sheet does not state a reference-device class for the irradiance sensor.
Build Quality & Durability
Compact and rugged-looking, but IP40 and a 0–2,000 m altitude limit mean it needs care on a dusty or wet site.
Fit & Ease of Use
Four measurements in one hand-held tool, with a mounting bracket and Bluetooth on the IRR2-BT.
Documentation, Warranty & Support
A detailed, dated technical data sheet with ordering contents; no warranty term is stated.
Value for Money
Not assessed — we have not sourced a current India price.
Strengths
- One tool for irradiance, temperature, tilt and compass
- Explicitly aimed at IEC 62446-1 testing and documentation
- Optional external suction-mount temperature probe (80PR-IRR) for module-back temperature
- IRR2-BT adds recording and wireless transfer to the SMFT-1000 for I-V curve measurements
Watch-outs
- Irradiance accuracy of ±(5% + 5 digits) is modest for tight performance-ratio checks
- Compass reads magnetic north and is only valid within ±20° of horizontal
- IP40 rating, AA batteries and no warranty stated on the sheet
- The IRR2-BT’s wireless transfer works with Fluke’s own SMFT-1000, not as a general data logger
Datasheet Specifications
| Irradiance | 50–1,400 W/m² · 1 W/m² resolution · ±(5% + 5 digits) |
|---|---|
| Temperature | −30 °C to +100 °C · 0.1 °C resolution · ±1 °C (−10 to +75 °C) |
| Inclination | ±90° · 0.1° · ±1.5° within ±50° |
| Compass | 0–360° · ±7° · referenced to magnetic north |
| Operating / storage temp | −20 to +50 °C operating · −30 to +60 °C storage |
| Protection / power | IP40 · 4 × AA, about 50 h (more than 9,000 readings) |
| Size / weight | 150 × 80 × 35 mm · 231 g |
| IRR2-BT extras | Bluetooth to SMFT-1000 · 64 kB / 6,400 records · about 17 h recording · mounting bracket |
| Standards / warranty | States support for IEC 62446-1 · EMC IEC 61326-1, CISPR 11 Class A · warranty not stated |
Specifications marked “datasheet-stated” are manufacturer figures we have not independently measured. Always confirm the exact model on its current datasheet before purchase.
Open the manufacturer’s datasheet for Fluke IRR1-SOL / IRR2-BT solar irradiance meterWho It’s For
- Installers and EPC teams documenting irradiance, tilt and orientation during survey and commissioning
- O&M technicians doing quick underperformance checks before a deeper investigation
- Teams already using Fluke’s SMFT-1000 PV analyzer
Our Verdict
A practical, well-documented all-in-one survey and commissioning meter whose ±5% irradiance accuracy is fine for surveys but thin for tight performance claims. Choose the IRR2-BT if you will also run I-V curves with Fluke’s analyzer, and remember the compass is magnetic.
Frequently Asked Questions
What is the accuracy of the Fluke IRR1-SOL irradiance meter?
The data sheet states ±(5% + 5 digits) over 50 to 1,400 W/m². At 1,000 W/m² that is roughly ±55 W/m², or about 5.5%.
What is the difference between IRR1-SOL and IRR2-BT?
The IRR2-BT adds Bluetooth, onboard recording (about 17 hours) and a mounting bracket, and sends data to Fluke’s SMFT-1000 PV analyzer. The IRR1-SOL measures the same quantities without the wireless module.
Does it give true north for panel azimuth?
No. The compass is referred to magnetic north with ±7° accuracy, so correct for local magnetic declination and keep it away from steel when documenting orientation.
Data Provenance
- Verified on
- 6 October 2026
- ALMM status
- Unknown — verify directly
- Source datasheet
- View official manufacturer datasheet
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