WriteNow@@@ @0@`x@3@`4@~ AAHHdFdd@YY@YY///>HHH@  >HHH@   @0@>@@X>@x@@$HH(FG(HH(d'@$ @DHLPTX\kATV}/80xP|0~~$4 ~HHH@0~$4 ~HHH@0~$4 ~HHH@0@~$4 ~HHH@PP$ PP$ 4Geneva 7?HH@Codes and Standards John Wiles c. 1993 John Wiles Like many behind the scenes areas of society, codes and standards are not in the public eye, are somewhat dull and boring and, at best, cause gleams only in the eyes of engineers. The renewable energy user and dedicated enthusiast should be aware of the fact that codes and standards have a very direct bearing on the performance and safety of their electrical power system. The Photovoltaic Power Industry is rapidly spreading beyond its grass-roots beginning and sustaining audience. The U.S. Coast Guard and the Forest Service are PV converts and ever growing users. Billboards are being illuminated all across the country by PV systems. Utilities are installing PV systems from 10 Watts to 500 kiloWatts (both grid connected and stand alone). Municipalities are finding that PV systems are cheaper than grid power even in central urban areas. Numerous residential consumers are being shocked into PV systems when they are told the costs of slightly remote grid connection. Public Service Commissions in many states require that the utility company provide the potential customer with a list of suppliers of alternate energy systems.  ORenewable Energy Systems Are Not Standardized At the present time, much of the equipment that goes into PV systems is not being produced to any particular standard. Three manufacturers (Siemens, Solarex, and Tidelands Signal) produce modules that are tested and listed to the same Underwriters Laboratories Standard; other modules that are widely available are not manufactured to any nationally recognized standard. Heart, Trace, and Dimensions Unlimited produce listed inverters, but they are listed by different testing agencies to different standards. Ananda Power has their Power Center listed by UL, and it includes a charge controller, but there are no separate charge controllers that are listed. DC-rated, UL-listed load centers, switches, fuses, and circuit breakers are available to the PV dealer/installer, but there are substantial amounts of non-listed equipment being manufactured and used by the PV industry. What is the import of using non-standardized equipment? Safety and Performance Are The Issues  In practical terms, while the system may appear to work, it may not be working efficiently or safely. In some systems, if a fuse were to blow or circuit breaker to open under fault conditions, the charge controller might not respond well to the new configuration and be destroyed. If disconnects are in improper locations or opened in the wrong order, the charge controller may be damaged, or unsafe voltages might be applied to the load circuits. If accidental grounds occur, the charge controller might not be able to control the charging process properly. When non-standardized generators and inverters are connected to the ac load center, currents can travel in unexpected, unsafe paths and create hazards (see Code Corner in Home Power 34). The improper selection of cables for the PV array wiring and the battery to inverter wiring can cause fire hazards, particularly if overcurrent devices have not been used. AC Systems Are Standardized The alternating current power system that has been in residential and commercial use in the U.S. for the last 80 plus years is relatively safe because all of the equipment commonly used is built to standards written by Underwriters Laboratories (UL). Every piece of equipment in the ac system bears the UL mark, from the 19-cent plastic outlet cover plate to the service entrance load center. This UL-listed equipment is installed in a manner that meets the requirements established by the National Electrical Code (NEC). The NEC was first printed in 1897 and has been revised every three years under the auspices of the National Fire Protection Association by professional volunteers from throughout the electrical power and equipment industries. Licensed electrical contractors or trained electricians install the equipment to NEC requirements. G Standardized equipment with specifically defined interfaces, when installed using a code that is in harmony with the equipment standards, provides for a safe, durable, and high performance electrical power system. Renewable Energy Users Unite Users of renewable energy should be afforded the same levels of safety and performance that the ac users of the nation enjoy. They should demand standardization of the equipment and compliance with the appropriate codes. Standardization is coming and code compliance can be achieved today. The NEC has had a section on PV since 1984 and 90% of the remainder of the code is applicable to any electrical power system including renewable systems. The user has to require that his or her installer meet the NEC requirements. An electrical inspection by the local inspection authority will help to ensure that the system is safe. The author of this column had four changes accepted for the 1993 NEC and is submitting over 40 changes for the 1996 code, all of which will benefit the renewable energy industries and the renewable energy user.  gThe author is also working, under the sponsorship of Sandia National Laboratories, with the Institute of Electrical and Electronic Engineers (IEEE) and Underwriters Laboratories to get standards published for inverters and charge controllers. Standards and Codes won't solve all of the problems that we face. Sometimes "Things Don't Work." PV equipment manufacturers need to continue to improve the basic product and build it to the available standards. Dealers and Installers need to learn more and more about their trade. Systems that have been installed by a team consisting of the user, the dealer/installers, an electrical contractor, and the electrical inspector have proved the most durable, the safest, and the best performing. Consumers should expect and demand nothing less. Access Author: John Wiles, Southwest Technology Development Institute, P.O. Box 30001, Dept 3 Solar, Las Cruces, NM 88003 505-646-6105 4 C־Geneva` EOD/p@   @@G@@_ @0@=`@0@`x@3@` 4@q2`q2hqqq2qqrqy8"q~n 1dAAHHdFdAAd@/YH@_Ve!!!