Solar Photovoltaics
Updated: March 2026
Technologies, efficiencies and market developments
1 How it works
The photovoltaic effect
The photovoltaic effect is the direct conversion of light into electricity at the atomic level. Discovered by Edmond Becquerel in 1839, it relies on semiconductor properties.
Photons strike the cell and transfer their energy to silicon electrons
The P-N junction creates an electric field that separates charges
Direct current (DC) is collected and converted to alternating current (AC) by the inverter
Photo: Unsplash
System components
Photo: Unsplash
PV Modules
Light to DC electricity conversion
Inverter (Inverter)
Conversion DC → AC + MPPT
Meter / Monitoring
Measurement of production and grid injection
2 Cell technologies
Monocrystalline (mono-Si)
Pure silicon with single crystal structure. Uniform black cells.
✓ Best surface efficiency
✓ High performance in low light
PERC / PERC+
Passivated Emitter and Rear Cell. Rear reflective layer.
✓ Excellent value for money
✓ Mature and reliable technology
TOPCon
Tunnel Oxide Passivated Contact. Contacts passivated by tunnel oxide.
✓ Better thermal performance
✓ Ideal for bifacial
HJT (Heterojunction)
Heterojunction Technology. Amorphous silicon layers on crystalline silicon.
✓ Efficiency record
✓ Excellent bifaciality
✗ Higher cost
Bifacial Modules
Capture light from both sides. Gain via ground reflection (albedo).
✓ Significant extra production
✓ Ideal for utility-scale and trackers
Perovskites
ABX₃ crystalline materials. Promising in tandem with silicon.
✓ Potential efficiency >30%
✓ Low manufacturing cost
✗ Durability yet to be proven
3 Technology comparison
| Technology | Efficiency | Temp. Coeff. | Price (€/Wp) | Bifaciality | Maturity |
|---|---|---|---|---|---|
| PERC Mono | 21-22% | -0.35%/°C | 0.15-0.20 | 70% | Mature |
| TOPCon | 22-23% | -0.30%/°C | 0.18-0.25 | 85% | Growing |
| HJT | 23-24% | -0.26%/°C | 0.25-0.35 | 92% | Premium |
| Tandem Perovskite | 28-33% | TBD | TBD | N/A | R&D |
* Indicative utility-scale module prices, Q1 2025. Source: PV InfoLink, BNEF
4 Trends & Innovations
Agrivoltaics
Agriculture and PV synergy. Crop protection, dual income.
Floating Solar
Floating PV on lakes and reservoirs. Natural cooling, no land footprint.
BIPV
Building Integrated PV. Solar tiles, facades, glazing.
Solar Trackers
Single/dual-axis sun tracking. +25-35% production gain.
5 Agrivoltaics & Carports Strong growth
Agrivoltaics
Agriculture + solar energy synergy
Agrivoltaics combines agricultural production and electricity generation on the same plot. Panels protect crops (heat, hail, frost) while generating additional income for the farmer.
Installation types
France regulations (2024)
+40%
Projects in 2024
3-5 GW
France potential 2030
💡 Key point: Agrivoltaics is not "disguised ground-mounted PV". The decree mandates a proven agricultural benefit (climate protection, reduced water stress, improved animal welfare).
Parking Carports
Legal obligation + high profitability
Solar canopies cover outdoor parking lots. They generate electricity while protecting vehicles (sun, hail) and reducing heat islands.
⚠️ Legal obligation (APER Law 2023)
Economic data
11 GW
France potential
+IRVE
EV charging synergy
💡 Opportunity: Combining solar canopy + EV charging stations (IRVE) maximizes project value: direct self-consumption for EV charging, green image, and regulatory compliance.
Storage & Batteries
Technologies, economics and solar + storage hybridization
1 Why storage has become essential
Intermittence
Solar only produces during the day. Storage enables evening consumption.
Price arbitrage
Store when prices are low, sell when they are high.
Grid services
Primary reserve, frequency regulation, capacity = additional revenues.
Avoid curtailment
Store rather than lose production during peaks.
Key BESS (Battery Energy Storage System) market figures
-90%
Battery cost drop since 2010
Source : IRENA 2024
$117/kWh
BESS system cost (2025)
Source : BNEF 2025 (-31% vs 2024)
200 GWh
Global deployment 2024
375 GWh cumulative, record
$56-80/kWh
Target range
Source : RMI, NREL 2025
2 Battery technologies
Lithium-ion NMC
Nickel-Manganese-Cobalt. High energy density, losing ground to LFP for stationary storage.
✓ High density, industrial maturity
✗ Cobalt (cost, ethics), thermal risk
Lithium Iron Phosphate (LFP)
Cobalt-free, safer and cheaper. ~70% of global BESS market.
✓ Safety, longevity, cobalt-free, cost
✗ Lower density (larger footprint)
Sodium-ion (Na-ion)
Lithium-free alternative. Abundant and cheap materials. First EU utility-scale deployment (Germany, Sept 2025).
✓ Abundant materials, very low cost
✗ Lower density, maturity yet to prove
Flow Batteries (Vanadium)
Long-duration storage (4-12h). Energy stored in liquid electrolytes. Independently scalable power/energy.
✓ Long duration, scalable, long lifespan
✗ Lower efficiency, larger footprint
| Technology | Density (Wh/kg) | Cycles | Efficiency | Cost ($/kWh) | Usage |
|---|---|---|---|---|---|
| Li-ion NMC | 150-260 | 1000-2500 | 90-95% | ~128 | EV |
| LFP | 90-120 | 3000-8000 | 92-96% | ~70 | Standard BESS |
| Na-ion | 120-160 | 2000-4000 | 88-92% | ~59 | Emerging |
| Vanadium Flow | 15-25 | 15000+ | 70-80% | 300-500 | Long Duration |
2025 costs. Sources: BNEF 2025, IRENA Technology Brief 2025, NREL ATB 2024.
3 Solar + Storage: new business models
Revenue Stacking
Combining multiple revenue streams to maximize hybrid system profitability:
Energy arbitrage
Buy/store during off-peak, sell during peak hours
Primary reserve (FCR)
Grid frequency regulation, RTE contracts
Capacity
Capacity mechanism, availability guarantee
Peak shaving
Reduce subscribed power demand for industrials
Hybrid configurations
AC-coupled
Battery connected on AC side via dedicated inverter. More flexible, allows retrofit on existing plants.
DC-coupled
Battery connected on DC side, shares PV inverter. More efficient (fewer conversions), lower cost.
Hybrid AC+DC
Combines both approaches. Optimal for large utility-scale projects. Maximum flexibility.
💡 Trend 2025
DC coupling is becoming the standard for new utility-scale PV+BESS projects.
LCOE of hybrid PV + Storage systems
PV only (utility-scale)
30-45 €/MWh
PV + Batterie (2-4h)
50-80 €/MWh
PV + Batterie (4h+) + Services
Competitive vs gas
Key point: With revenue stacking (arbitrage + FCR + capacity), hybrid projects achieve equity IRR of 10-15%, higher than PV alone.
Source: IRENA 2024, US hybrid projects: average LCOE $0.079/kWh (4.5 GW PV + 7.7 GWh storage)
4 Green hydrogen: long-duration storage
Principle
Green hydrogen is produced by water electrolysis using renewable electricity (solar, wind). It enables energy storage over long durations (days, weeks, seasons).
1. Solar production
Low-cost green electricity
2. Electrolysis
H₂O → H₂ + O₂ (efficiency 60-80%)
3. Storage / Transport
Compression, liquefaction, or conversion (ammonia)
Green hydrogen economics
🎯 Key factor
Electricity cost represents 60-70% of H₂ cost. A low solar LCOE = competitive green H₂.