Based on the 2020 NEC

by Mark Lamendola

National Electrical Code Tips: Article 690 -- Solar Photovoltaic Systems, Part 1

Only about 15% to 20% of the work of installing a Solar Photovoltaic (PV) System is electrical. But that electrical portion can easily result in disaster if not done correctly. Thus, Article 690 provides requirements for that portion. This article has become more complex since it was first released. Partly, that's because the Code Making Panel has learned (as all CMPs do) how the initial requirements affected actual installations and adjusted from there. Also, installers and other parties have given input on each Code cycle. As solar panels become more ubiquitous, you can expect Article 690 to keep changing. In fact, Part I has been almost completely rewritten over the past three code cycles. It is vastly different in 2020 from what it was in 2011.

  1. Article 690 does not cover small solar-powered devices, such as patio lamps, flashlights, automobile ventilators and other assorted gadgets. These do not supply power to premises wiring.
  2. Article 690 does cover solar power systems, including those that are interactive with other power systems  [690.1]. These do supply power to premises wiring.
  3. The NEC provides a simple diagram that clearly illustrates PV system components [Figure 690.1(a)]. No matter how complex or advanced a PV system is, it will have these system components. Study the diagram, and you will see why.
  4. The NEC provides a set of simple diagrams that clearly illustrate solar photovoltaic (PV) system components in three common system configurations [Figure 690.1(b)]. These are stand-alone, hybrid, and interactive.
  5. A hybrid system is one comprised of several power sources [100 and Figure 690.1(b)]. For example, if you combine a wind turbine generator with a solar system you have a hybrid system. What do you get when you cross a dog with a.... :)

  6. A system is "interactive" if it connects to the power network [100 and Figure 690.1(b)].
  7. A charge controller is different from a diversion charge controller. The former controls the dc voltage (or dc current) use to charge a battery [100]. The latter regulates the battery charging process by diverting power from energy storage to the load or to the utility [694.2]. Article 690 used to contain both definitions in 690.2, but the first has moved to Article 100 and the second is no longer defined in the NEC. The closest definition is the one provided for wind power systems, thus the 394.2 reference.
  8. You still must apply Chapters 1 through 4, but where the requirements differ from Article 690 then you go with the Article 690 requirements. This used to be stated in 690.3, but the caveat applies to every article in Chapters 5 through 8 unless otherwise noted [Figure 90.3].
  9. If the PV system operates in parallel with a primary source of electricity (e.g., the electric utility), that makes it an interconnected source. Which means Article 705 also applies.
  10. If you install a PV system in a hazardous location (as defined by OSHA and as defined in Article 500), you must apply the relevant Articles 500 through 516. A location is hazardous if the presence of combustibles is high enough to risk a fire. If the combustibles are gases, dust, or fibers, the location is Class I, Class II, or Class III respectively.

Bonus material:

  1. You can install a PV system to supply a structure, even if other systems also supply it [690.4(A)]. This is, in fact, the most common arrangement for PV systems. Relatively few structures rely solely on solar.
  2. The major components of a PV system must be listed for the use or evaluated for the application and have a field label applied [690.4(B)] (see list of components in 690.4(B)--inverters, motor generators, PV modules, PV panels, or charge controllers, etc).
  3. Only qualified persons can install and wire the PV system electrical components  [690.4(C)]. Keep in mind that the NEC uses the OSHA definition of "qualified" and it has a specific legal meaning. See Article 100 for this definition. In the case of PV systems, the most pertinent part is the installer "has received safety training to recognize and avoid the hazards involved." That means training specific to this type of installation. Such training may be provided by the manufacturer or a manufacturer-approved party. A firm that regularly installs PV systems and has a training program in place can most likely be the source of such training for new installers under its supervision.
  4. If you use multiple PV systems for a single structure and they are remote from each other, you must you must provide a 705.10-compliant directory at each PV system  [690.4(D)]. The reason for this requirement is so fire fighters can easily locate all of these energy sources.