Kilovolt (kV)
A kilovolt (kV) is a unit of electrical potential equal to 1,000 volts. In the solar industry, kilovolts are used to describe the voltage levels of inverters, transformers, medium-voltage (MV) distribution systems, and utility interconnection equipment. Understanding kilovolt ratings is essential for designing safe, efficient, and code-compliant PV systems—especially commercial and utility-scale projects.
Solar arrays generate DC voltage, but once converted to AC, solar power is often stepped up into kilovolt ranges to reduce current, minimize line losses, and enable efficient transmission. Designers, EPCs, and installers must understand kV ratings when selecting cable sizes, configuring MV transformers, planning interconnection, and ensuring compliance with AHJ and NEC requirements.
Key Takeaways
- A kilovolt (kV) equals 1,000 volts and represents medium to high electrical voltage levels.
- Solar systems use kV ratings primarily on the AC side, especially after inverter output.
- Commercial and utility-scale projects rely heavily on 4.16–34.5 kV distribution systems.
- Understanding kV levels is critical for transformer selection, cable design, safety planning, and interconnection engineering.
- SurgePV tools simplify kV-related planning for solar designers and EPC teams.
What Is a Kilovolt (kV)?
A kilovolt (kV) is a measure of electrical force or potential difference. It indicates how strongly electricity can push through a conductor. Higher voltage means lower current is needed to transmit the same amount of power, which reduces resistive losses and allows smaller cables to be used.
In solar applications, kilovolt ratings apply to:
- Inverter AC output voltage
- Medium-voltage transformers
- Grid interconnection points
- Utility feeders
- Switchgear and protection equipment
Understanding kV levels is critical for designing electrical systems that align with local grid standards and equipment specifications.
Related concepts include Voltage, Inverters, and Stringing & Electrical Design.
How Kilovolts Work in Solar Systems
Kilovolts come into play primarily on the AC side of a solar PV installation. Here’s how they fit into the system:
1. Solar panels generate low-voltage DC
Modules produce around 30–60 volts each. Strings may combine into 600–1500V DC depending on the system.
2. Inverters convert DC → AC at specific kV levels
Common inverter AC outputs include:
- 208V or 400V for commercial systems
- 480V for larger buildings
- 600V–1000V in some specialty systems
3. Transformers step up AC to medium voltages
To reduce losses and transmit power efficiently, MV transformers increase voltage to:
- 4.16 kV
- 11 kV
- 13.8 kV
- 22 kV
- 33 kV
4. Medium-voltage switchgear manages distribution
At kV levels, systems require specialized switchgear, protection relays, and interconnection hardware.
5. Utilities transmit and distribute at high kV levels
Large-scale solar farms interconnect with feeders whose ratings are often:
- 34.5 kV
- 69 kV
- 115 kV
- 230 kV and higher
Kilovolts are central to grid integration and safe power transmission.
Types / Levels of Kilovolt Ratings in Solar
1. Low Voltage (LV) — < 1 kV
- Residential & small commercial
- Common outputs: 120V, 230V, 400V, 480V
2. Medium Voltage (MV) — 1 kV to 69 kV
Most common for commercial and utility-scale solar.
Used for:
- Transformer secondary outputs
- Feeder distribution
- On-site interconnection
See Inverter Sizing for how AC voltage determines inverter configuration.
3. High Voltage (HV) — 69 kV and above
Used in:
- Transmission lines
- Utility tie-ins for large solar farms
How Kilovolts Are Measured
Kilovolt levels are measured using:
Voltage meters and digital analyzers
Rated for LV/MV/HV depending on system level.
Transformer tap measurements
Used to validate correct output voltage levels.
Utility protection devices
Provide real-time voltage monitoring for interconnection points.
Formula Reminder:
1 kV = 1,000 V
Practical Guidance for Solar Designers & Installers
1. Match inverter AC output to site electrical infrastructure
Choosing the wrong voltage leads to expensive redesigns.
2. Use correct cable sizes for kV systems
Higher voltage = lower current, but insulation requirements increase.
3. Verify transformer compatibility
Ensure primary and secondary voltages fit local grid requirements.
4. Follow NEC and utility interconnection guidelines
Medium-voltage work requires licensed professionals and strict protocols.
5. Use software tools for AC calculations
SurgePV tools such as Solar Designing help with layout and electrical planning.
6. Plan switchgear and protection early
Equipment for MV/HV systems requires procurement lead time.
7. Confirm POI (Point of Interconnection) requirements
Work with utilities to define acceptable voltage levels.
Real-World Examples
1. Commercial Rooftop System
A 500 kW installation uses 480V inverter output, then steps up to 4.16 kV for on-site distribution.
2. Utility-Scale Solar Farm
A 50 MW plant configures central inverters feeding into a 34.5 kV collection system, then steps up to 115 kV for grid export.
3. Industrial Microgrid
A factory installs a solar + storage system operating at 13.8 kV for direct tie-in to their medium-voltage switchgear.
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