HiQ System Features
Solar PV systems are known to cause fires. This is not surprising given that typical installs are comprised of many, many high voltage connections, arising from the stringing of PV modules serially together. The combination of high voltage (up to 1,000Vdc) and many manual installation steps where the probability of imperfect connector mating is high, makes arcing a real and frequent risk. To protect against this, US rules require PV systems to have arc detection. However recent fires demonstrate that there is a gap between product compliance, and the detection of real-world arcs in the field.
Reliable detection of real arcs is a very difficult engineering problem. It is easier for an inverter with single strings, and placed close to the array than for large string inverters placed long distances away from the array and with strings paralleled together. These large string inverters, and also central inverters, may turn to the use of combiner boxes, which separate the strings and do arc detection per string. These devices must then communicate with the inverter to shut off when an arc is detected. Clearly this entails a lot more hardware, more failure points, more headache, more costs.
The TrueString architecture of HiQ Solar solves this problem simply and reliably.
The video below, and the photos to the right show results from some customer testing of a real-world arc produced by a test fixture positioned in the middle of a string of PV modules. A variety of AFCI-compliant string inverters were tested, and none detected the arc except the HiQ Solar TrueString.
AFCI compliant inverter failing to detect and extinguish a real-world arc.
Arc being detected and extinguished by a HiQ TrueString inverter.