Key Takeaway
A complete photovoltaic installation comprises 7 essential components: solar panels (mono or polycrystalline silicon modules), the inverter (string, micro-inverters, or optimizers), wiring and photovoltaic connectors (MC4), a bidirectional meter, a monitoring system, electrical protection devices (circuit breakers, surge protectors, DC disconnect switches, residual current devices), and the mounting structure. Each component must be properly sized and certified according to IEC standards and local wiring regulations for optimal safety and performance.
1. Solar panels: the heart of the installation
The solar panel — or photovoltaic module — is the component that converts sunlight into electricity through the photovoltaic effect. Each panel consists of silicon cells connected in series, protected by tempered glass and an aluminum frame.
| Type | Efficiency | Appearance | Main advantage | Recommended use |
|---|---|---|---|---|
| Monocrystalline | 20 – 24% | Uniform black | High efficiency, compact | Limited space, high output required |
| Polycrystalline | 15 – 18% | Blue marbled | Lower cost | Large rooftops, limited budget |
| Thin-film | 10 – 13% | Gray/matte black | Flexible, lightweight | Non-standard surfaces, low load capacity |
Panel power is expressed in watts-peak (Wp), representing maximum output under standard test conditions (STC: 1,000 W/m², 25°C). Current residential panels typically deliver between 400 and 500 Wp per module.
2. The inverter: the brain of the system
The inverter converts direct current (DC) produced by the panels into alternating current (AC) compatible with the electrical grid and household appliances. It is the most strategic component after the panels.
| Type | Principle | Advantage | Disadvantage | Ideal use |
|---|---|---|---|---|
| String inverter | Single device for all panels or a group of panels (string) | Lower cost, centralized maintenance | Sensitive to partial shading (one weak panel affects entire string) | Uniform rooftop, no shading |
| Micro-inverters | Individual inverter under each panel | Panel-by-panel optimization, no shading effect | Higher cost, distributed maintenance | Multiple orientations, partial shading |
| Optimizers + central inverter | DC-DC optimizer per panel + central inverter | Performance/cost compromise, per-panel monitoring | Intermediate cost | Mixed installations |
3. Wiring and photovoltaic connectors
Wiring carries current from the panels to the inverter, then to the electrical panel. In photovoltaic systems, cables and connectors must withstand particularly demanding conditions.
1DC solar cables
Specific cables resistant to UV, heat (90°C minimum), humidity, and weather. Typical cross-section: 4 mm² to 6 mm² for residential installations, up to 10 mm² or more for commercial systems. They must be certified to EN 50618 or equivalent.
2MC4 connectors
Industry-standard photovoltaic connectors enabling quick, waterproof (IP67) and reliable connections between panels and to the inverter. They must be from the same manufacturer or cross-certified to ensure optimal contact and prevent hot spots.
3AC cables
Between the inverter and electrical panel, wiring is standard AC. Cross-section is sized according to inverter power and cable run length, in compliance with local wiring regulations.
⚠️ Safety point
Never mix MC4 connectors from different manufacturers without cross-compatibility certification. Poor contact can create a hot spot reaching several hundred degrees and cause a fire.
4. Electrical protection devices
Photovoltaic installation safety relies on several complementary protection devices, distributed across the DC side (panel side) and AC side (grid side).
| Device | Protects against | Side | Standard |
|---|---|---|---|
| DC disconnect switch | PV array isolation for maintenance or emergency | DC | IEC 60947-3 |
| DC fuses / circuit breakers | Overcurrent (short circuit, overload) on panel side | DC | IEC 60269, IEC 60947-2 |
| DC surge protector | Overvoltage (lightning, switching) | DC | IEC 61643-31 |
| AC circuit breaker | Overcurrent on grid side | AC | IEC 60947-2 |
| AC surge protector | Overvoltage on grid side | AC | IEC 61643-11 |
| Residual current device | Earth leakage current (electrocution) | AC | IEC 61008 |
5. Bidirectional meter
The bidirectional meter (or smart meter) simultaneously measures energy consumed from the grid and energy exported to the grid (production surplus). It is essential for:
- Self-consumption with surplus sale: the meter measures exactly the surplus exported, serving as the billing basis.
- Full export: all production is exported and measured for remuneration.
- Performance tracking: it allows comparing production and consumption to optimize energy use.
6. Monitoring system
Monitoring enables real-time tracking of production and proper system operation. Most modern inverters include a monitoring platform accessible via mobile app or web interface.
A good monitoring system provides:
- Real-time production tracking: instantaneous power, cumulative energy (kWh), daily curves.
- Anomaly detection: alerts for abnormal production drops, inverter faults, or communication failures.
- Per-panel monitoring: with micro-inverters or optimizers, you can identify exactly which panel is underperforming.
- History and statistics: monthly and annual comparisons, and return-on-investment projections.
7. Mounting structure
Panels must be securely fixed to the support (roof, ground, pergola, carport) with appropriate structures:
- Roof-mounted (on-roof): panels are installed above existing roof tiles. The most common solution for residential installations.
- Building-integrated (BIPV): panels replace roof tiles and serve as the roof covering. Aesthetically pleasing but more complex and costly.
- Ground-mounted: self-supporting structures or on piles, with optimized tilt and orientation. Common for large ground-mounted systems.
- Solar trackers: motorized structures that follow the sun's path. Increase production by 20-30% but higher cost and maintenance.
Photovoltaic system architecture overview
| Stage | Component | Function | Current type |
|---|---|---|---|
| 1 | Solar panels | Electricity generation (photovoltaic effect) | DC |
| 2 | DC wiring + MC4 connectors | Current transport from panels to inverter | DC |
| 3 | DC disconnect switch + fuses/breakers | PV array isolation and protection | DC |
| 4 | DC surge protector | Overvoltage protection on panel side | DC |
| 5 | Inverter | DC to AC conversion | DC → AC |
| 6 | AC circuit breaker + RCD | AC circuit protection | AC |
| 7 | AC surge protector | Overvoltage protection on grid side | AC |
| 8 | Bidirectional meter | Production / consumption measurement | AC |
| 9 | Electrical grid | Surplus export / grid supply | AC |
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Frequently asked questions — Photovoltaic installation
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Key takeaways
- A PV installation comprises 7 key elements: panels, inverter, wiring, protections, meter, monitoring, and mounting structure.
- Monocrystalline panels dominate the residential market thanks to superior efficiency (20-24%).
- The inverter is the most strategic component and the one that ages fastest (10-15 years).
- MC4 connectors must be compatible — never mix brands without cross-certification.
- A DC disconnect switch is mandatory — it must be specifically designed for direct current.
- DC and AC surge protectors shield the installation from lightning-induced overvoltages.
- A bidirectional meter is essential for self-consumption with surplus export.
