Installing the Compleo SOLO: process, RCD self-test and the most common mistake

The Compleo SOLO already has its RCD built in: type A, with 6 mA DC residual current detection and an automatic self-test. No upstream RCD is therefore required in the sub-distribution board. If one is installed anyway, it must be selective to the RCD in the station. Otherwise it also trips during the self-test and the SOLO loses power. This is a common installation mistake, not a product defect. In this article you will see how the self-test works, what matters with an upstream RCD and how the installation goes.

Contents

1. What is already built into the SOLO
2. How the RCD self-test works
3. Upstream RCD: not needed, but if there is one, it must be selective
4. The most common mistake and how to spot it
5. Installation step by step
6. Commissioning and measurements
7. Conclusion
8. Frequently asked questions

What is already built into the SOLO

With most wallboxes, part of the protection technology sits in the distribution board. All SOLO wallboxes have it inside the enclosure:

• Type A RCD with 30 mA rated residual current
• 6 mA DC residual current detection, so no type B RCD is needed
• Overvoltage protection
• Self-test and automatic reset via the sliding cover of the socket or cable holder, which Compleo calls Service RCD

This saves space in the board and real money. Only a miniature circuit breaker with characteristic C has to be installed in the sub-distribution board, which makes a difference of up to €200 on installation. Compleo specifies C20 A for 11 kW and C40 A for 22 kW. The manual for your station always takes precedence.

You also save costs in day-to-day operation: if the RCD has tripped once, nobody has to go to the board and no technician has to come out. Pushing the sliding cover up is enough, and the station resets itself. Only a permanent fault requires a visit from a qualified electrician.

SOLO smart, advanced and premiumline differ only in the meter, the display, the housing cover with viewing window, the power of the socket version (11 or 22 kW) and the PLC module, which only the premiumline has.

Important: The built-in RCD protects everything from the wallbox onwards, not the supply line before it. How the supply line is protected is decided by your qualified electrician in line with local regulations and verified by measurements.

How the RCD self-test works

An RCD has to be tested regularly, otherwise nobody knows whether it will trip in an emergency. The SOLO does this itself:

1. Test: At the set time, the controller generates a residual current and the built-in RCD trips. Models with a display show a T.
2. Switching back on: The next time the sliding cover is pushed up, the RCD switches back on. This completes the test.
3. Documentation: The result can be viewed in DUCTO and is reported to a connected OCPP backend.

In its maintenance plan, Compleo provides for the self-test every six months. The qualified electrician sets the interval in DUCTO in the Currents folder. If the test fails, customer service must be notified.

Tip: If your SOLO suddenly stops working after months of trouble-free operation, push the sliding cover up once first. Often it was just the self-test.

The self-test comes in addition to maintenance, not instead of it. Compleo still recommends an annual inspection by a qualified person.

Important: Regardless of the self-test, the legal obligations of the country concerned apply. Your qualified electrician will clarify which RCD tests and maintenance are required for your installation and how often.

Upstream RCD: not needed, but if there is one, it must be selective

The SOLO does not need its own RCD in the sub-distribution board. Even so, there may be one in the circuit, for example because the supply line is connected to an existing RCD or because the installation or the grid operator requires one. Then sensitivity is what counts.

The reason is simple: the residual current from the self-test also flows through the RCD in the board. If that RCD has the same 30 mA as the RCD in the station, it is just as sensitive and also trips. Compleo points out that an additional RCD can interfere with the automatic self-test, which can lead to faults and device failure. A required additional RCD must therefore be selective to the built-in one.

Selective means that in the event of a fault, only the RCD closest to the fault trips. According to ABB, two conditions must be met for this:

• Current: The rated residual current of the upstream RCD is at least three times that of the downstream one.
• Time: The shortest non-tripping time of the upstream RCD is above the maximum permissible tripping time of the downstream one.

Your qualified electrician decides which RCD meets this in your installation.

In the sub-distribution board	SOLO self-test	Assessment
Miniature circuit breaker, no RCD	runs	The normal case
Selective RCD and MCB, or selective RCBO	runs	Selective to the RCD in the station
30 mA RCD, instantaneous (type A, F or B)	station loses power	Also trips, deactivate self-test in DUCTO
30 mA RCD, short-time delayed (type G)	station loses power	Not selective, deactivate self-test in DUCTO

Good to know: A selective RCD with a higher rated residual current does not replace the 30 mA protection of other circuits. If sockets are also connected to it, they still need their own 30 mA RCD.

The most common mistake and how to spot it

A typical case: the new circuit for the wallbox is connected downstream of the existing 30 mA RCD. On installation day everything works and the station charges normally. Only during the self-test does the RCD in the board trip and the SOLO lose power. Because this happens months later, it looks like a defect. But it isn't: the station is doing exactly what it should.

These signs point to it:

• The RCD in the sub-distribution board has tripped.
• The SOLO can no longer be reached, neither via DUCTO nor via app or backend.
• Other devices on the same RCD also have no power.
• Pushing the sliding cover up does nothing, because the station has no voltage.
• After switching the RCD back on, everything works again until the next self-test.

There are three options:

1. Installation with a miniature circuit breaker: The wallbox gets its own circuit with an MCB that does not run through the 30 mA RCD. This is usually the simplest solution.
2. Installation with a selective RCD: If an RCD is needed upstream of the wallbox, a selective RCD with MCB or a selective RCBO is used.
3. Deactivating the self-test in DUCTO: If a non-selective upstream RCD remains, the qualified electrician can deactivate the self-test function. The automatic test then no longer runs and the RCD must be tested manually, in line with the legal requirements of the country concerned.

Tip: The mistake can be found as early as commissioning. If the RCD in the board also trips during the RCD test at the SOLO, the protection is not right. Better for your electrician to notice this straight away than for the station to fail six months later.

Installation step by step

Only a qualified electrician may connect the SOLO. The values below come from the current operating manual of the SOLO premiumline and apply equally to smart and advanced. For your station, the enclosed manual applies. Before connection, the wallbox must also be notified to the grid operator, which your electrician usually takes care of.

1. Choose the location: At least 90 cm above the floor and 15 cm below the ceiling, on a wall strong enough to carry the station. The mounting surface must not be more than ± 3 mm uneven.
2. Mount vertically: The station must hang exactly vertically. According to Compleo, an incorrect mounting position can interfere with the built-in RCD. The connection box has a built-in spirit level for this.
3. Fix the connection box: Five holes 8 mm in diameter and 60 mm deep, plus wall plugs, screws and washers from the accessory pack.
4. Connect the supply line: Use copper cable only. Strip around 70 mm of the sheath and 18 mm of the conductor insulation, then connect L1, L2, L3, N and PE. The terminals take rigid conductors up to 10 mm² and flexible ones up to 6 mm²; the tightening torque is 1.5 to 1.8 Nm. The qualified electrician determines the cross-section according to power, length and installation method.
5. Hook in the lower shell: Hook it in at a 45-degree angle, swing it down and tighten with five screws at 1.5 Nm. The multi-pin connector of the internal supply line then clicks into the terminal block.
6. Connect data and control: Network cable via RJ45 or LSA terminal, and if required a ripple control receiver and SIM card.
7. Close the cover: Fit the housing cover and secure it at the bottom with two TORX screws at 1.5 Nm.

Tip: Plan the protection before drilling: where in the board will the new miniature circuit breaker sit, and does the circuit run through an RCD? This way you avoid the mistake described above. You can read how the setup works in principle in Compleo eBOX & SOLO: installation made easy.

Commissioning and measurements

Before the first charge, the qualified electrician checks the protective measures and function. After switching on, the SOLO needs around 60 seconds to start up. In DUCTO the electrician logs in with the “Login as electrician” checkbox, because this is the only way to change settings such as currents and the RCD self-test.

Compleo supplies a test report for this. The most important limit values from it:

Test	Limit according to the report
Protective conductor	low resistance, below 1 Ω recommended
Insulation resistance	at least 1.0 MΩ
Phase sequence	clockwise rotating field
Mains voltage	230 V or 400 V, ± 10 %
Relative voltage drop	maximum 5 % up to the feed point
RCD, AC tripping current	above 12 mA, at most 30 mA
RCD, AC tripping time	below 300 ms at 1 × IΔN, below 40 ms at 5 × IΔN
DC sensor	tripping at no more than 6 mA, positive and negative edge, in under 10 s

The report template is based on German standards. In Austria and other countries, the respective national regulations apply.

If you want to see the measurements: Compleo shows them in short videos in its YouTube playlist on installation and commissioning, including:

• Checking the RCD, AC (t+I)
• Checking the RCD, DC (t+I)
• Loop impedances at the terminal block
• Function tests at the type 2 socket

If the SOLO is to run via app, this can be done at the same time: Controlling the Compleo SOLO with an app. We explain what applies to grid connection in Austria in our article on OVE R 37.

Conclusion

The built-in RCD with self-test is one of the SOLO's biggest advantages: up to €200 less on installation, no type B RCD, a test that takes care of itself and a reset via the sliding cover that saves costs in operation. For this to work, there must be no standard 30 mA RCD upstream. If an RCD is needed in the board, it must be a selective one. Clarify this before installation and you will have peace of mind with the SOLO for a long time.

Frequently asked questions

Do I need an RCD in the sub-distribution board for the SOLO?

No. The type A RCD sits in the station along with the 6 mA DC residual current detection and overvoltage protection. The board only needs the miniature circuit breaker. Your qualified electrician will clarify whether the installation requires an RCD for other reasons.

Do I need a type B RCD?

No. The built-in DC residual current detection switches off at smooth DC residual currents from 6 mA, so the type A RCD is sufficient.

The RCD in my board keeps tripping. Is the wallbox broken?

Not necessarily. If it happens at regular intervals, the self-test is usually the cause. This is not a product defect but a question of installation. If the RCD trips more often or during charging, have your qualified electrician check the installation.

The SOLO no longer charges, but the RCD in the board is on. What should I do?

Push the sliding cover up once. After a one-off trip, this switches the built-in RCD back on. If it trips again straight away, there is a permanent fault and a qualified electrician needs to come out.

Can I simply switch off the self-test?

Only the qualified electrician can do this in DUCTO. This makes sense if an upstream RCD remains and selectivity cannot be achieved. The RCD must then be tested manually, in line with the legal requirements of the country concerned.

Does the self-test replace maintenance?

No. The legal obligations for testing and maintenance depend on the country concerned and also apply with the self-test. Your qualified electrician will clarify what is required for your installation.

Can I connect the SOLO myself?

No. Mounting, connection and commissioning belong in the hands of a qualified electrician. If you don't have one, we can put you in touch with one from our partner network on request. Write to us at onlinesales@ampion.at.

I need help with an installed SOLO.

Send us your enquiry with the station's serial number to service@ampion.at.

Matching products

• Compleo SOLO smart cable – with 6.5 m coiled cable
• Compleo SOLO smart socket – with type 2 socket
• Compleo SOLO Pole Single pedestal – for mounting without a wall

As of: November 2026. This article provides technical guidance and replaces neither your station's operating manual nor planning by a licensed electrical contractor.

Sources: Compleo Document Center SOLO, Operating manual SOLO premiumline, Compleo: Service RCD, Operating manual Compleo SOLO N, ABB: Selectivity of residual current devices