Design Article
Setting safety standard for arc detection in solar industry
Brett Novak, Texas Instruments
1/22/2013 1:15 PM EST
TI’s SM73201-Arc-Eval Photo-voltaic arc detection system
Figure 7 shows TI’s SM73201-Arc-Eval Photo-voltaic arc detection system containing a C2000 Piccolo microcontroller. The SM73201-Arc-Eval Photo-voltaic arc detection system provides a number of important features that allow developers to create reliable arc detection systems capable of accurately identifying arcs without producing unwanted false positive detections (Table 1).
Table 1: Features of TI’s SM73201-Arc-Eval Photo-voltaic arc detection system
Click on image to enlarge
New micro-inverter topology: no need for arc detection
As mentioned earlier, an alternative micro-inverter topology is becoming available that is aimed at residential installations (Figure 8). Each PV panel has its own micro-inverter and as the DC voltage is less than 80 V for each micro-inverter it falls outside the scope of UL 1699B as it can operate safely without arc detection. The key benefits of micro-inverter-based over string-based topologies are greater flexibility, ease of installation, and scalability.
Micro-inverters, however, have cost disadvantages i.e. they are costly to install and the cost per watt is inferior to string-based topologies. Consequently, until the cost of micro-inverters falls significantly, the majority of solar installations (99 percent) will continue to be developed using the string approach. Furthermore, the additional cost of complying with UL 1699B and the need to include an arc detection unit is minimal, compared with the overall system cost. As string inverters will continue be used in solar installations for some considerable time to come, developers with need to take in to consideration the requirements of UL 1699B when designing solar equipment.
Figure 7 shows TI’s SM73201-Arc-Eval Photo-voltaic arc detection system containing a C2000 Piccolo microcontroller. The SM73201-Arc-Eval Photo-voltaic arc detection system provides a number of important features that allow developers to create reliable arc detection systems capable of accurately identifying arcs without producing unwanted false positive detections (Table 1).
Table 1: Features of TI’s SM73201-Arc-Eval Photo-voltaic arc detection system
Click on image to enlarge
Figure 7: The SM73201-Arc-Eval photovoltaic arc detection system
New micro-inverter topology: no need for arc detection
As mentioned earlier, an alternative micro-inverter topology is becoming available that is aimed at residential installations (Figure 8). Each PV panel has its own micro-inverter and as the DC voltage is less than 80 V for each micro-inverter it falls outside the scope of UL 1699B as it can operate safely without arc detection. The key benefits of micro-inverter-based over string-based topologies are greater flexibility, ease of installation, and scalability.
Figure 8: Micro-inverter topology
Micro-inverters, however, have cost disadvantages i.e. they are costly to install and the cost per watt is inferior to string-based topologies. Consequently, until the cost of micro-inverters falls significantly, the majority of solar installations (99 percent) will continue to be developed using the string approach. Furthermore, the additional cost of complying with UL 1699B and the need to include an arc detection unit is minimal, compared with the overall system cost. As string inverters will continue be used in solar installations for some considerable time to come, developers with need to take in to consideration the requirements of UL 1699B when designing solar equipment.
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William Miller
3/19/2013 11:14 AM EDT
Using solar energy is economically efficient but as we can see from this article, - not as easy as it may seem. And here is a question for specialists - will I be able to install a system like that for my house by myself, or do I need a sort of authority approval and/or papers?
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William - http://www.carid.com/
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