The RDE300i from Atonometrics is an in-situ PV module I-V curve measurement system for utility-scale solar power plants. It performs periodic I-V sweeps while the module remains connected in the string — measuring open-circuit voltage (Voc), short-circuit current (Isc), maximum power (Pmax), and the full current-voltage characteristic — without disrupting inverter operation. Compatible with crystalline, thin-film, bifacial, and monofacial modules rated up to 30A, 250V, and 1500W.

How does the RDE300i measure soiling without taking modules offline?

Using patent-pending technology that keeps the module near its maximum power point during sweeps, the RDE300i captures the full I-V curve without interrupting string current. The built-in RTD temperature sensor (IEC 60751 Class A) provides module temperature correction, enabling accurate calculation of soiling ratio — the loss in short-circuit current due to dust and debris accumulation compared to a clean reference. Performance ratio and effective irradiance (including bifacial total irradiance) are also computed. All measurements comply with IEC 61724-1 Class A for PV system performance monitoring.

How does the RDE300i integrate into a solar plant monitoring network?

Each RDE300i communicates via Modbus RTU over RS-485 and draws less than 1W from a 10–30 VDC supply. An AUX port allows daisy-chaining of multiple RDE300i units and Atonometrics sensors — including RC22 reference cells and soiling sensors — on a single communication bus. The IP66 enclosure withstands outdoor installation at ambient temperatures from -40°C to +65°C. CE and RoHS certified, the RDE300i integrates with major SCADA and plant management systems through standard Modbus register mapping.