Single-Phase Photovoltaic AC Protection Panel QAC 1/3 kW
Single-phase AC protection panel for photovoltaic systems from 1 to 3 kW, 16 A 230 V. Integrates a 300 mA Class A residual current circuit breaker with overcurrent protection, in/out configuration and Class II SPD surge arrester 2P 230 V 15 kA.
12-module IP65 box, supplied with single-line diagram and declaration of conformity. It does not include interface protection: it is designed for systems below the 11,08 kW threshold.
The single-phase AC panel QAC 1/3 kW provides protection on the alternating-current side of a small residential photovoltaic system, to be installed between the inverter and the home’s main distribution board. It performs three tasks: isolating the inverter for maintenance, protecting the AC line against overloads and earth faults, and limiting overvoltages coming from the grid.
Warning: this is not an interface panel
This is the distinction that causes the most purchasing errors. CEI 0-21 requires an Interface Protection System (SPI) external to the inverter, with the related interface device and backup system, only above 11,08 kW of total power. Below that threshold, the interface protection integrated in the certified inverter is sufficient, and the distributor requires neither a dedicated SPI nor a relay test report.
This panel therefore belongs to the category of AC protection and isolation panels: it is the correct choice for a single-phase system from 1 to 3 kW. If your system exceeds 11,08 kW, you need a three-phase interface panel with SPI and test report, not this one.
Why the residual-current device is Class A and not AC
Downstream of a photovoltaic inverter, the earth fault current may contain DC components or unidirectional pulsating components. An AC-type residual-current device, calibrated only for sinusoidal alternating currents, may fail to detect the fault precisely when it should trip. For this reason, the panel is fitted with a Class A 300 mA thermal-magnetic residual-current circuit breaker, also sensitive to pulsating components. The 300 mA threshold provides protection against fires and system faults, not protection against direct contact: that remains the responsibility of the 30 mA residual-current device in the home distribution board.
QAC 1/3 kW technical specifications
| System power | From 1 to 3 kW |
| Grid type | Single-phase 230 V |
| Rated current | 16 A |
| Main protection | Thermal-magnetic residual-current circuit breaker (IMTD) 16 A, 300 mA, Class A |
| Configuration | In/out switch |
| Overvoltages | Class II SPD surge arrester, 2P, 230 V, 15 kA |
| Interface protection | Not present (systems below 11,08 kW) |
| Enclosure | IP65 box with 12 modules, 115 x 220 x 200 mm |
| Documentation | Single-line diagram and declaration of conformity |
| Weight | 2 kg |
What the in/out configuration means
The in/out arrangement allows the line to be branched without interrupting the feeder: the panel input and output are already wired to dedicated terminal blocks. In practice, the panel is inserted on the existing line without having to create intermediate joints, reducing potential fault points and simplifying future maintenance or inverter replacement.
Frequently asked questions
Is this panel enough for the connection procedure with the distributor?
For a single-phase system below 11,08 kW, yes: the distributor requires the system declaration of conformity, the single-line diagram and the inverter certification, which already includes the interface protection. The SPI relay test report is required only above that threshold.
Can I use it on a 4 or 5 kW system?
No, it is not sized for that. At 230 V, a 4,5 kW inverter delivers about 20 A, and a 6 kW inverter about 26 A, exceeding the capacity of the 16 A switch. For those sizes, 25 A and 32 A versions are available in the same series.
Is the panel already wired or do I have to assemble it?
It arrives factory-assembled and wired, with a single-line diagram and the panel declaration of conformity. The installer only needs to connect the inverter line and the line to the main distribution board on the prearranged terminal blocks.
Is it still needed if my inverter already has integrated protections?
Yes. The inverter protects itself and manages the interface protection, but the AC line between the inverter and the main distribution board must have its own overcurrent protection and an accessible isolation device. This is a CEI 64-8 requirement for any circuit, not something specific to photovoltaics.
Is the SPD surge arrester really useful on a small system?
Yes, and it is often the only component that pays for the panel by itself. Overvoltages induced by indirect lightning strikes travel along the grid and find the inverter to be the weakest point in the system. A 15 kA Class II surge arrester upstream costs a fraction of the power board it protects.