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How Erasmus University turned a glass atrium into a 25kW solar power plant
The design paradox: solar power in a daylit building
“Natural where possible, mechanical where necessary”
When Erasmus University Rotterdam commissioned the 8,400m² Polak Building in 2014, they needed a Dutch GPR sustainability score of 8.5 while maintaining Paul de Ruiter Architects’ vision of transparency and natural light flooding through a central atrium. Traditional rooftop solar panels would block the very daylight the design sought to maximize. Standard PV arrays didn’t fit that philosophy.
Generate power without blocking daylight
The atrium’s central position made it ideal for solar generation — unobstructed sky view, large surface area — but conventional panels would have created a dark, enclosed space. The building needed to achieve ambitious sustainability targets whilst students experienced abundant natural light below. Limited roof space outside the atrium (occupied by HVAC equipment) meant alternative locations couldn’t deliver the required capacity.
Why it fits: By embedding high-performance PERC monocrystalline cells into semi-transparent insulated glass units, ISSOL® Square achieved 50% transparency — enough natural light for comfort while harvesting energy overhead. Most visitors don’t realize they’re standing beneath an active solar array. The dark cells create dappled shadow patterns complementing warm wood interiors — integration done right.
Engineering that works
| Parameter | Value | Notes |
|---|---|---|
| Application | Semi-transparent atrium | Central atrium overhead glazing |
| ISSOL® solution | ISSOL® Square | Uniform square cell grid |
| Active atrium area | ±285 m² | BIPV-integrated skylight surface |
| Atrium capacity | 25.2 kWp | Full atrium skylight system |
| Power density | ~88 Wp/m² | Based on total skylight surface area |
| Transparency | ~50% | Optimized for daylight + performance |
| Annual yield | 20,000–22,000 kWh/yr | ~800 kWh/kWp; 5-10% of building demand |
| Glass build-up | Custom DGU safety glass + EVA | Extra Clear glass with low-E coatings |
| Cell technology | PERC monocrystalline | Square cell grid; architectural consistency |
| Integration | Concealed cabling in mullions | No visible conduits; thermal expansion loops |
| Building size | 8,400 m² | Polak Building total floor area |
| Building cert. | GPR design score 8.5 | Dutch sustainability rating |
“Natural where possible, mechanical where necessary — the solar cells are integral to the sustainability strategy, mentioned alongside daylighting and ventilation. Not an add-on, but fundamental to how the building works.”
Paul de Ruiter Architects — Design philosophy
Semi-transparent solar architecture
Performance monitoring data — 5+ years validated operationAvailable on request →
