« Devis clair, sans surprise, primes comprises. Un seul interlocuteur du début à la fin. Je recommande sans hésiter pour le photovoltaïque. »
Pierre M.Tournai
Solar · Cell technology
The photovoltaic cell: how a silicon cell makes electricity from light
At the heart of a panel, the photovoltaic cell is a silicon cell that converts light directly into current. Here we get into the technology: the photovoltaic effect, the junction, cell efficiency, peak power in Wp and real-world behaviour under Belgian skies. Enough to understand what you are really buying.
- ~950 kWh/kWp
- Belgian yield / year
- −0.30%/°C
- heat coefficient
- 25–30 years
- production warranty
Photovoltaic effectlight → electricity
Efficiency 21–23%recent cells
Technical specifications
What really happens inside a PV cell
The parameters that describe a photovoltaic cell and module. Concrete benchmarks for reading a spec sheet without being dazzled by marketing.
- Photovoltaic effect P-N junction
The cell is a thin silicon wafer doped in two layers. When a photon strikes the junction, it frees an electron: this movement of charges creates a direct current. No mechanism, no moving part — just light and the semiconductor.
- Cell technology PERC · TOPCon · HJT
Monocrystalline PERC remains the standard; TOPCon adds a passivation layer for higher efficiency, and heterojunction (HJT) combines crystalline and amorphous silicon for the best performance and a low temperature coefficient.
- Efficiency 21–23% module
Cell efficiency (often 23–25%) is always higher than module efficiency, which accounts for the gaps, the glass and the frame. It is module efficiency that determines the power per m² of roof.
- Peak power 430–500 Wp
Peak power (Wp) is measured under STC conditions: 1000 W/m² of sunlight, cell at 25°C, standardised spectrum. It is a comparison reference; real output in Belgium depends on orientation and weather.
- Temperature coefficient −0.30%/°C
A heated cell produces less. For each degree above 25°C, power drops by about 0.30% (PERC) to 0.26% (HJT). Under Belgium’s temperate skies, the impact stays moderate and works in favour of output.
- Module architecture Half-cut · bifacial
Half-cut cells and multiple busbars reduce resistive losses and poor behaviour in shade. Bifacial also captures light reflected from the rear — a bonus on a light-coloured roof or on the ground.
* Indicative values for mainstream monocrystalline modules (PERC/TOPCon/HJT). Exact performance depends on the maker, the model and the installation conditions — confirmed in your study.
In full transparency
Strengths & limits of the photovoltaic cell
PV technology is mature and reliable, but its figures should be read with nuance. Here, honestly, is what the cell does very well and what to keep in mind.
Where it shines
- Direct, silent conversionNo moving part, no combustion: light becomes current, with no mechanical wear.
- Rising efficienciesTOPCon and HJT push module efficiency beyond 22%, meaning more Wp per m² of roof.
- Good low-light behaviourRecent cells produce from dawn and under cloudy skies — valuable in Belgian weather.
- Slow degradation and warrantyAbout 0.4–0.5%/year of loss, with a 25 to 30-year production warranty (≥ 87% at the end).
What to keep in mind
- Wp ≠ real outputPeak power is measured in the lab (STC); Belgian yield runs around 950 kWh/kWp/year.
- Sensitive to temperatureIn full sun, the cell heats up and loses a few percent: rear ventilation matters.
- Sensitive to shadeA shaded cell holds back its chain; half-cut architecture and optimisers limit the damage.
- Misleading cell efficiencyA fine advertised cell efficiency does not carry over as-is to the fitted module.
For which project
Which cell technology for you?
The right cell depends on your roof and your goal. A few concrete cases where each technology takes the lead:
-
Well-exposed roof
On a clear south slope, monocrystalline PERC offers the best efficiency/price ratio. The proven technology, ideal for most Belgian homes.
-
Limited surface or shade
When every m² counts or a chimney casts shade, TOPCon and half-cut cells maximise the Wp and cope better with partial shading.
-
Ground or flat-roof mounting
On a light, well-ventilated surface, bifacial HJT captures light reflected at the rear and limits heat losses: extra output.
Not sure which technology to choose?
Before comparing cells, set the scene: discover the types of solar panels by use, or the overview of the installation on solar panels.
Glissez la poignée pour comparer
Real case · roof renovation, Namur
Same roof m², +60% power thanks to the cell
On a limited roof, the customer was hesitating to go solar for lack of surface. By choosing 450 Wp TOPCon half-cut cells rather than old 270 Wp modules, we fitted 1.6 times more power on the same surface — without touching the framework.
- +60%of Wp for the same surface
- 22.4%module efficiency
- ~950kWh/kWp/year expected
Customer reviews
They chose wendows
5.0/5 · 1verified reviews
Compare the options
The cell, or the big picture?
This page digs into the cell and the module. To compare uses or discover plug-and-play formats, open the dedicated pages.
| Critère | PV cellVous êtes ici | Panel typesVoir la gamme → | Balcony panelVoir la gamme → |
|---|---|---|---|
| Angle of the page | The cell & its technology | Formats by use | The ready-to-plug kit |
| Technical level | In depth | Comparative | General public |
| Efficiency covered | Cell vs module | By type | Overall |
| Typical power | 430–500 Wp / module | Depending on use | 300–800 Wp / kit |
| Implementation | Roof-mounted | Roof / ground | Balcony, no works |
| Temperature coefficient | Detailed | Mentioned | Not covered |
| Ideal for | Understanding the technology | Choosing a format | Tenant / small budget |
Indicative benchmarks. Every roof is unique: we refine the technology and the power in your free solar study.
- to go further
Panel types
Monocrystalline, bifacial, solar tiles: compare formats and uses rather than the cell alone.
Compare the types → - to combine
Solar inverter
The cell produces direct current: the inverter turns it into usable alternating current. The key link for real output.
Understand the inverter → - to combine
Solar roof
Orientation, tilt, shade: the roof determines what your cells will really produce each year.
See the solar roof → - to combine
Solar battery
Store the surplus from your cells to climb in self-consumption and use your own sun in the evening.
Discover the battery → - budget
Personalised study
Which technology, how many Wp, what yield at your place: we cost everything in a free study.
Request my study → - ↑ category
All about solar
An overview of our photovoltaic installations in Belgium: equipment, fitting, self-consumption and subsidies.
Back to the solar guide →
Indicative price 2026
How much does a photovoltaic cell cost?
A module’s price depends on the cell technology, the power and the brand. We mainly think in €/Wp and at the level of the complete installation. Here are some benchmarks for supply-and-fit.
See a costed solar study →* Indicative ranges for mainstream modules, supply and fitting. The exact estimate is made during your free solar study.
- PERC 430 Wp module from €0.30/Wpstandard, fitted, excluding inverter
- TOPCon / HJT module €0.35–0.45/Wphigh efficiency, fitted
- 4 kWp installation from €6,000turnkey, inverter included
- Reduced VAT 6%in renovation (home > 10 years)
Photovoltaic cell FAQ
Your questions about the PV cell
How does a photovoltaic cell produce electricity? +
Through the photovoltaic effect. The cell is a thin silicon wafer doped in two layers forming a P-N junction. When a photon of light strikes it, it frees an electron; the movement of these charges creates a direct current. No moving part, no combustion: it is the light that does the work directly.
What is the difference between cell efficiency and module efficiency? +
Cell efficiency measures the conversion of an isolated cell, often 23 to 25%. Module efficiency, in turn, accounts for the gaps between cells, the glass and the frame: it is always lower, around 21 to 23%. It is the latter that determines how many Wp you fit per m² of roof.
PERC, TOPCon, HJT: which to choose? +
Monocrystalline PERC offers the best price/performance ratio and remains the standard. TOPCon adds a passivation that gains a few efficiency points. Heterojunction HJT aims for top efficiency and the best heat behaviour. On a limited or shaded roof, paying for TOPCon or HJT is justified; on a large, clear south slope, PERC is often enough.
What does peak power in Wp mean? +
Peak power (Wp, watt-peak) is measured under standard test conditions: 1000 W/m² of sunlight, cell at 25°C and a standardised light spectrum. It is a comparison reference between modules, not the real output. In Belgium, you harvest on average about 950 kWh per kWp installed per year, depending on orientation and weather.
Does heat reduce the cell’s output? +
Yes. Above 25°C, each extra degree loses about 0.30% of power for a PERC cell, a little less for HJT (≈ 0.26%). That is why good ventilation at the rear of the modules matters. Belgium’s temperate climate limits this effect: our moderate summers are rather favourable to output.
How long does a photovoltaic cell last? +
A cell loses about 0.4 to 0.5% of power per year. Makers generally warrant 25 to 30 years of production, with at least 87% of the initial power at the end. In practice, a cell fitted today will still produce most of its potential three decades from now.
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