The distance (10 meters) is exclusive of conductors that are provided with or used to attach SPDs.
Type 3: Point of utilization SPDs, installed at a minimum conductor length of 10 meters from the electrical service panel to the point of utilization, for example cord connected, direct plug-in, receptacle type and SPDs installed at the utilization equipment being protected.The Imax value is the maximum single discharge current represented by an 8/20 µs waveform that the SPD can support. Type 2: Permanently connected SPDs intended for installation on the load side of the service equipment overcurrent device including SPDs located at the branch panel and molded case SPDs.Type 1 SPDs for use in PV systems can be connected between the PV array and the main service disconnect. Type 1: One port, permanently connected SPDs, except for watt-hour meter socket enclosures, intended for installation between the secondary of the service transformer and the line side of the service equipment overcurrent device, as well as the load side, including watt-hour meter socket enclosures and molded case SPDs intended to be installed without an external overcurrent protective device.UL 1449 defines type 1, type 2, and type 3 SPDs: SPDs provide protection against the hazards caused by surges. To do this, all conductive surfaces should be directly grounded and all wiring that enters and exits the system (such as Ethernet cables and ac mains) be coupled to ground through an surge protection device (SPD).Ī SPD is needed for each group of the strings within the array box, the recombiner box, as well as the dc disconnect. To prevent high energy from passing through electronics and causing high voltage damage to the PV system, voltage surges must have a path to ground.
The array box, the inverter, and the MPPT (maximum power point tracker) device have the highest points of failure. These transient currents and voltages will appear at the equipment terminals and likely cause insulation and dielectric failures within the solar PV electrical and electronics components such as the PV panels, the inverter, control and communications equipment 2, as well as devices in the building installation 3. When lightning strikes a solar PV system, it causes an induced transient current and voltage within the solar PV system wire loops. Inverters are expensive, but for industrial applications, an even more expensive failure is the cost of downtime. When a PV system is located on an industrial site, the business operations and equipment are also at jeopardy. Indirect lightning strikes can be fatal if the person is within 60 feet from the point of the lightning strike. If a surge occurs when any personnel are present, it will jeopardize their safety as well. The more expansive the field is, the more likely destruction is to occur.Įlectronic equipment can easily be damaged to the point of catastrophic failure by surges. When this happens, a voltage surge is likely to occur. Charged rain clouds that accumulate over such open fields have the propensity to release the charge in the form of lightning. PV systems are exposed in large open spaces, typically in fields or on the tops of buildings.
The overvoltage depends on the setup conditions of each PV system and the wirings. Indirect lightning strikes can easily damage the sensitive components within PV equipment, which often has a high cost to repair or replace the damaged components and affects the PV system’s reliability 1. Anecdotal observations about lightning activity is usually a poor indicator of the level of lightning-induced overvoltages in PV arrays 1. Indirect lightning strikes are destructive. Nimbus clouds cause the biggest surges because they are what generate lightning. The ionization of air that is between the ground and the nimbus clouds creates a discharge from the clouds to the ground. Nimbus clouds (rain clouds) have a concentration of electrical charge, and their accumulation creates an ionization of air. When lightning strikes, fires are prone to happen due to the release of energy.
Lightning is an electrical discharge in the atmosphere. Solar panels’ large-and often exposed and isolated-location make surge protection critical for it to last its lifespan. Lightning’s perfect storm for destruction is on the solar field.
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