Setting safety standard for arc detection in solar industry
Brett Novak, Texas Instruments
1/22/2013 1:15 PM EST
Meeting the UL 1699B standard
As the vast majority of existing solar installations run DC lines over 80 V, to meet UL 1699B when it is introduced they will require retrofitting with a fairly simple standalone arc detection unit (arc detection subsystem and circuit breaker) placed between the inverter and the string of panels. In contrast, in new installations arc detection and string inverter functionality can be integrated on the same processor cost-effectively. Texas Instruments’ (TI) high-performance F2803x and F2806x microcontrollers are well suited to high voltage solar applications:
• A high level of integration with full-featured peripheral sets minimizes arc detection and breakaway circuitry external components
• TI’s C2000 microcontroller platform offers the optimal balance of performance, peripherals, and memory
• Enables maximum system efficiency by providing sufficient capacity to perform additional tasks
A single arc detection unit using a high-performance processor can simultaneously analyze many strings. This enables the component count to be minimized, which lowers the cost of the system and reduces potential failure points (Figure 6).
Figure 6: A single arc detection unit
Systems can be made further cost effective by combining arc detection and other solar application processing tasks on a single multiple/dual core processor. This reduces system complexity and provides addition processing power that enables greater efficiency/reliability. TI’s C2000 Piccolo microcontroller platform, for example, enables Maximum Power Point Tracking (MPPT) by providing a second core (the Control Law Accelerator [CLA]) that operates independently of the arc detection DSP core as it has access to the C2000 Piccolo microcontroller ADC and PWM peripherals. Having MPPT (which maximizes PV panel efficiency) and arc detection on a single processor adds considerable value to solar applications.