OMAT Core Knowledge: Tasks and Knowledge Items

30% of the OMAT exam

Core Knowledge is the biggest single domain at 30%, up from 20% on the PV Associate exam. Five tasks cover PV system types, components and their functions, electrical concepts, codes and standards, and equipment specifications. Note what the JTA does and does not name: it says "Electrical codes (e.g., national, state, and local codes)" — it never names the NEC. Expect questions about what a code requirement is for, not about article numbers.

Task 1: Types of PV Systems

PV Direct
Stand-alone
- Same Fault Code, Two Sites, One Truck: Which First?
Grid-tied
Multimode (i.e., grid-tied with energy storage)

Task 2: Components of PV Systems and Functionality

PV modules
Mounting structures
Inverters (e.g., string, micro, multimode, central)
- The Grid Is Out. Is the AC Side Dead?
Power electronics (e.g., rapid shutdown devices, DC-to-DC converter)
Energy storage
Load control
Balance of system (BOS) components (e.g., panelboard and disconnects, raceways and conduit, wire and conductors, overcurrent protection devices)
Monitoring equipment
Grounding and bonding elements (e.g., equipment grounding conductor, grounding electrode conductor, grounding electrode, bonding jumper)

Task 3: Electrical Concepts

Photovoltaic effect
Ohm’s law
- Millivolt Drop on a Hot Connection: What the Numbers Mean
Power and energy (i.e., watts verses watt-hours)
- Watts or Watt-Hours? One Figure in This Report Is Wrong
Electrical measurements (e.g., voltage, current, impedance, resistance)
Alternating current (AC) and direct current (DC)
Single-phase, split-phase, and three-phase circuits
Series and parallel circuits
- One String Reads 80 V Low, Current Normal: What Changed?
Grounding and bonding (e.g., system and equipment)
- A Cut Bonding Jumper, No Production Loss: Can It Wait?

Task 4: Codes and Standards

Electrical codes (e.g., national, state, and local codes)
Building codes (e.g., national, state, and local codes)
Fire codes (e.g., national, state, and local codes)
- The Fire Marshal Says Move It. Whose Rule Is That?
Workplace safety standards (e.g., OSHA, ANSI, NFPA)

Task 5: Equipment Specifications

PV module specifications (e.g., Standard Test Conditions [STC], open circuit voltage, short circuit current)
- 400 W Nameplate, 318 W Measured: Are the Modules Failing?
Manufacturer documentation (e.g., datasheets, installation manuals)
Inverter specifications (e.g., voltage, current, frequency, surge)
Existing service and/or equipment (e.g., voltage, current, phase)
Energy Storage Systems (e.g., type, capacity, voltage)
National recognized testing labs [NRTL]
- Two Connectors That Click Together, Two Different Makes
Product safety standards (e.g., IEEE standards, UL, national standards)
Location conditions (e.g., wind, snow, seismic activity)