The sun shines on BIPV

A worker at the 10 MW Masdar solar plant in Abu Dhabi.
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Seamless integration
The company’s Multisol modules can be integrated seamlessly into the architecture of any building, or even retrofitted without any major problems. They are available in three different sizes and various performance classes, meaning optimal flexibility for customised requirements.

Features include a sturdy aluminium frame for straightforward installation, together with a patented pluggable connection system.

The frame has a wide glass insertion depth to be able to withstand winds, while the plug system at the edges ensures solid interconnection of all frame components. The modules boast such attention to detail as an internal groove providing rapid drainage for any condensation.

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The International Energy Agency (IEA) comments that, “in order to assess the potential of BIPV, an analysis of the building stock with respect to suitability of the building skin for PV deployment is required.

Some building surfaces will have technical limitations; others will have limited capabilities to generate PV power due to inadequate orientation, inclination or shading effects.” The IEA defines such suitability in two main categories:

• Architectural suitability includes corrections for limitation due to construction (HVAC installations, elevators, terraces, etc.), historical considerations, shading effects and use of the available surfaces for other purposes; while
• Solar suitability takes into account the relative amount of irradiation for the surfaces, depending on their orientation, inclination and location, as well as the potential performance of the PV system integrated into the building.

The IEA concludes that, with a good solar yield assumed to be 80%, the achievable level of solar-power production by PV roofs and façades varies from 15% to 60% (the ratio used is BIPV solar-power production potential over current electricity consumption).

The achievable level depends ultimately on the building area available, as well as on solar radiation levels and electricity consumption.

All these factors imply that BIPV could have a massive potential in the UAE, where major players like Scheuten are positioning themselves carefully to take advantage of the ‘desert renewables boom’.

Future potential
So let us look a bit closer at what BIPV entails, as well as its future potential. The National Renewable Energy Laboratory (NREL) notes that “the integration of PV panels into buildings during construction is one of the fastest-growing segments of the solar industry.”

Steven Strong from Solar Design Associates, described as North America’s oldest and most respected renewable-energy design firm, says there is burgeoning international interest in using PV elements as an ‘exterior weather skin.’ He says that PV specialists and innovative designers in Europe, Japan and the US are now exploring ‘creative’ ways of incorporating solar power into their work.

“A whole new vernacular of solar energy architecture is beginning to emerge,” comments Strong. This is good news for the MEP sector, because where there are architects, there is a need for MEP contractors and consultants …

A complete BIPV system comprises the following elements:

• PV modules (thin-film or crystalline, transparent, semi-transparent or opaque);
• A charge controller to regulate the power into and out of the battery storage bank (in standalone systems);
• A power-storage system;
• Power-conversion equipment (including an inverter to convert the DC output from the PV modules into compatible AC current);
• Back-up power supplies (such as diesel gensets); and
• Appropriate support and mounting hardware (wiring and safety disconnects).

Below are some important design considerations associated with BIPV systems.

• Shift the peak: If the peak building loads do not match the power output of the PV array, batteries can be incorporated to offset the most costly load periods. This system can also serve a dual function as an UPS;
• Ensure adequate ventilation: High operating temperatures have a detrimental effect on PV conversion efficiencies. This means allowing appropriate ventilation behind modules in order to dissipate the heat;
• Integrated daylighting and PV collection: By using semi-transparent thin-film modules, or crystalline modules with custom-spaced cells between two layers of glass, designers can use PV to create unique daylighting features in façade, roofing or skylight PV systems. The BIPV can also mitigate the additional cooling load and glare associated with large expanses of architectural glazing;
• Shading devices: Conceiving PV arrays as awnings over viewing-glass areas of a building can provide the necessary passive solar shading. When sunshades are taken into account as part of an integrated design approach, chiller capacity can be reduced, while perimeter cooling distribution may even be totally obviated.

Relatively new
Finally, the Research Institute for Sustainable Energy (RISE) cautions that the use of BIPV is still relatively new.

“Ensure that the design, installation and maintenance professionals involved with the project are properly trained, licensed, certified and experienced in PV systems work,” it urges contractors.

While there are numerous companies in the UAE supplying solar-energy products and systems, the relative newness of the technology means there is a potential dearth of installation and maintenance experience. This is one arena where the MEP sector can stand the construction industry in good stead by filling this gap.