The success of Henry Ford’s Model T, starting production in 1908, is attributed to many innovations by automotive historians and experts. Many claim that his use of an assembly line or paying workers an efficiency wage were the keystones of the Ford Motor Company’s rapid growth and prosperity. A view less often heard comes from Womack, Jones and Roos, authors of “The Machine that Changed the World,” which just so happened to be required reading for the only mechanical engineering course this electrical engineer ever took. They argued that Ford’s actual success stemmed from the then new capability to machine pre-hardened steel. Automotive production before the advent of the Model T was more of a bespoke process where each part of an automobile would need to be filed or machined in order to appropriately fit with other parts. If your car needed a new crankshaft, for instance, a mechanic who was also part machinist was necessary to mate the new crankshaft to the existing engine block, piston rods, etc. Being able to machine pre-hardened steel allowed the consistent interchangeability of parts making production, repair, and ultimately automobile ownership easier.
In 100 or so years from now when historians look back at the success of Photovoltaic (PV) generation in the electric power sector, particularly the distributed energy resource (DER) versions, it is interesting to conjecture what they will attribute the growth of the industry to, from less than 1 GW installed capacity about a decade ago to nearly 50 GW now. Surely the rapid decline in PV panel cost and governmental policies, such as net metering and direct incentives, have been critical to the rapid growth. However, if we look deeper, I think the future historians with a technical background will find that the standardization of DER interconnection also played an outsized role.
IEEE 1547 was first published in 2003. It greatly aided PV interconnection in the early years when a 100 kW PV system was considered huge. The standard provides an understanding of the expected operational characteristics of the generator under normal and abnormal conditions. Furthermore, UL 1741, which is based on IEEE 1547.1 – Standard Conformance Test Procedures for DER, provides for the certification of equipment which adheres to the IEEE 1547 standard. Certified equipment became widely available after UL 1741 was first developed. It allowed the industry to broadly implement DER’s with understood and tested behavior when connected to the utility grid.
Much as the venerable Model T was replaced by the Model A in 1927, IEEE 1547 has recently undergone a major redesign. Make no mistake that IEEE 1547-2003 did a major service to the industry, but times have changed. We now have much more distributed PV connected to the grid than most or all imagined possible in the early 2000’s when IEEE 1547 was developed. Also, many service territories around the U.S. and the world now regularly experience interconnection scenarios including many 100’s if not 1000’s of PV systems which are interconnected on a single distribution circuit, or at least many systems confined to clusters within specific areas. These “high penetration” challenges, and many more including the potential for reliability-related impacts from DER on the bulk system, have necessitated a rethink of interconnection requirements. The revision of IEEE 1547, currently nearing completion, is the product of 130 working group members and 389 balloters who made over 1500 comments on the initial ballot. All are working to make the new version of IEEE 1547 the best it can be. Major changes and revisions include the harmonization of the standard with NERC voltage and frequency ride-through requirements, harmonization of voltage regulation requirements with state rules such as California’s Rule 21 and Hawaii’s 14H, and interoperability requirements for DER equipment.
While many view the revision of IEEE 1547 as a positive step forward for standardizing future DER interconnections, others will understandably lament the passing of the relatively basic interconnection-related functionality required in the original 2003 version. Progress is never painless and many entities, including the IEEE Power and Energy Society in partnership with NERC, the U.S. Department of Energy, and UVIG’s DER Working Group, have been ramping up outreach activities so that interconnection practitioners can become familiar with the new IEEE 1547 prior to its official widespread adoption.
As anyone who has driven an electric or hybrid car recently can attest, the automotive industry has innovated immensely since the Model T, but many things are also still similar, such as the fact that most cars still have four wheels just as they did in the early 1900’s. Similarly, the new revision of IEEE 1547 will still allow efficient DER interconnection, but with DERs capable of the functionality necessary for our continued safe, reliable and cost effective operation of the electrical grid with ever higher shares of DERs.
For more information on IEEE 1547 revisions please see: http://grouper.ieee.org/groups/scc21/1547_revision/1547revision_index.html
Barry Mather Ph.D.
Senior Engineer – National Renewable Energy Laboratory