Electricity takes a clear path: modules generate direct current, cables carry it to the inverter, which turns it into alternating current – and from the meter box everything is distributed as usual into the house or via the bidirectional meter into the grid. Important for you: electrical work is a matter for authorised specialist companies, at the end there is a safety certificate (SiNa) – and the secret cost factor of many projects is an old meter box. (As of: July 2026)
Key points in brief
- Two worlds, one system: direct current (DC) flows on the roof, alternating current (AC) from the inverter onwards – the boundary between the two is the heart of the system.
- Protection is built in: DC disconnection point, surge protection and fusing are standard – and the inverter switches off automatically in the event of a power failure.
- The grid operator's bi-directional meter measures consumption and feed-in separately – it is the basis of every bill, not your app.
- Electrical installations may only be carried out by businesses with the appropriate authorisation; they are signed off with the safety certificate.
- Practical cost factor number one: the meter box – in houses from the 60s to the 80s, it often needs an adaptation.
The path of electricity: from the module to the socket
Let's follow a kilowatt hour from the roof into the house – the entire structure explains itself along this path:
Station 1: the modules. They generate direct current (DC) – current that flows constantly in one direction. Several modules are connected in series to form strings; their cables run bundled down from the roof.
Station 2: the DC cables. Specially insulated, UV-resistant solar cables carry the direct current to the inverter – routed as shortly and protected as possible, because the DC side is the part of the system with its own safety rules. Upstream of the inverter is a disconnection point with which the roof side can be de-energised for work.
Station 3: the inverter. The active centrepiece converts DC into grid-compliant alternating current (AC) – with microinverters, this already happens under each module. Incidentally, it monitors the system and performs the most important protective function of all: in the event of a grid failure, it disconnects automatically so that there is no voltage from your roof on a disconnected line.
Station 4: the meter box. Here the system feeds into the domestic distribution board via its own fuse. From now on, the simplest rule of the system applies: the solar electricity takes the shortest route – first to the consumers in your own house, and only the surplus flows on through the grid.
Station 5: the meter. The grid operator's bi-directional meter records consumption and feed-in separately – it is the official measuring point on which your billing is based. Why its figures never exactly match the app is explained in the measurement guide: the app measures at the inverter, the meter at the house connection – in between lies your self-consumption.
Which protective devices are included in the system?
For everyday use, you do not need to operate any of them – but knowing that they exist answers the most common safety questions:
- DC disconnection point: makes the roof cables de-energised for service work.
- Surge protection: intercepts voltage peaks, for instance from thunderstorms in the area – on both the DC and AC side. (This is not a lightning conductor; whether actual lightning protection is required depends on the building, not on the system.)
- Fusing in the meter box: like any large consumer, the system is connected to its own fuses.
- Grid and system protection in the inverter: the automatic shutdown in the event of grid faults – the reason why a standard system does not continue to run in the event of a power failure.
- Earthing: module frames and the mounting structure are integrated into the equipotential bonding of the house.
In short: the system is not an improvised structure, but part of the electrical installation of the house – with the same protection principles and the same duty of care.
Who is allowed to connect all this – and what is the safety certificate (SiNa)?
Here, the legal situation is pleasingly clear: in Switzerland, electrical installation work may only be carried out by companies with the appropriate installation authorisation – the trade cannot be given to «just anyone», and reputable providers disclose their electrical partners of their own accord. ecoEn itself is registered with the ESTI for this – ESTI installation authorisation (Art. 14 NIV) for photovoltaic systems, no. SOB-284349-1. After completion of the work, the installation is inspected and documented with the safety certificate (SiNa) – the proof that it was built professionally. Together with the schematic and the acceptance protocol, it belongs in your system dossier; you will need it at the latest in the event of warranty claims or when selling the house.
The registration with the grid operator runs in parallel: connection request before construction, completion notification afterwards – your utility needs to know what is connected to its grid, and on this basis also provides the appropriate meter. All this is routine for the specialist company; your role is limited to checking that these items are in the quote.
The underestimated item: your meter box
If a solar project causes an electrical surprise, it is almost always here. The meter box – correctly: the domestic distribution board – is the hub where the system docks, and in houses from the 60s to the 80s it often no longer meets today's requirements: no space for additional outgoing circuits, outdated protection technology, sometimes simply no reserve space for the new meter.
Then an adaptation or renewal is due – no drama, but an item that belongs in the quote and not on the construction site. A provider who conducts a site visit before the quote looks precisely into this box; one who quotes based on an aerial photograph only discovers it when the surcharge is due. The consolation: the renewal makes the distribution board fit for everything still to come – wallbox, heat pump, battery storage will later be connected to the same hub.
What you need to know as an owner – and what you don't
The good news at the end: in operation, the system's electrics are maintenance-free in the everyday sense – there is nothing to lubricate, nothing to readjust, nothing you would need to touch. What remains are three points of knowledge:
1. Where the system is switched off – inverter and fuse; the installer will show you at the handover. Relevant almost only for tradesman appointments and the (rare) emergency. 2. That work is a matter for specialists – every modification to the installation, from an additional circuit to an expansion, goes through the authorised business, including an updated safety certificate. 3. Where the documents are kept – schematic, SiNa, acceptance protocol. Three documents that are worth their weight in gold at the right moment.
Everything else – standards, cross-sections, protection concepts – is rightly the trade of those who are trained and authorised for it.
Of all the trades in a solar project, the electrics are where concern and reality diverge the most – only in an unfamiliar direction. We are regularly asked about the roof («Will it hold?») and about the electricity («Is it dangerous?»); however, what surprises the projects is almost never the roof and almost never the DC side, but the meter box in the basement. Our site visit routine therefore basically ends in front of the domestic distribution board, with an open door and a photo – the two minutes spent there save the most frequent surcharge discussion in the industry. And an observation for reassurance: during the handover, we show every customer where the system is switched off. The vast majority do not need this handle a single time in twenty years – but everyone sleeps better knowing it.
Frequently asked questions
Is the direct current on the roof dangerous?
Built professionally: no – the DC side has its own safety rules (suitable cables, disconnection point, tested plugs), and that is exactly why it belongs in specialist hands. For residents, there is no risk of contact in normal operation; a respectful distance applies as with any electrical installation.
Does my meter box need to be replaced for the solar system?
Not fundamentally – but in older houses (typically from the 60s to the 80s) there is often a lack of space or up-to-date protection technology, in which case an adaptation is due. Whether this is necessary for you is shown by the site visit prior to the quote; the item belongs quantified in the quote, not as a surprise on the construction site.
What is the safety certificate (SiNa)?
The document with which the inspected, professional electrical installation is proven – it is created after completion of the work and belongs in your system dossier. In the event of warranty claims, the periodic inspection of the property and when selling the house, it is the proof that counts.
Will I get a new electricity meter due to the solar system?
As a rule, yes – a bi-directional meter is needed that measures consumption and feed-in separately; this is provided and changed by the grid operator. In many places, a smart meter is used straight away for this, which is being introduced comprehensively anyway.
Can my house electrician connect the solar system?
If he has the necessary installation authorisation and the solar installer agrees – yes, such constellations are feasible, but need a cleanly regulated interface (who delivers what, who is responsible for what). How this is solved contractually is shown in the article on general contractors and individual trades.
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Electrics without surprises.
Our quote is created after the site visit – meter box included. Connection, registrations and safety certificate come from a single source, with disclosed electrical partners.
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Swissolar-certified specialist company · ESTI installation authorisation (Art. 14 NIV) · in Zurich since 2017 · over 150 systems completed · a personal answer from the specialist company, no call centre
Sources: ESTI (requirements for electrical installations, general); empirical values from the installation and mounting practice of ecoEn GmbH, Zurich region.
Last updated: 9 July 2026 · Author: ecoEn editorial team
