Harnessing Solar Energy… Again
As part of No Impact Week, ADB officially turns on its second solar power plant on the rooftop of the new Third Atrium building at ADB’s headquarters in Manila, Philippines.
Written by Naomi Lissa Cruz
ADB staff and guests witnessed this week the ceremonial switch-on of ADB’s new solar power plant under sunny—albeit slightly cloudy—skies on the rooftop of the Third Atrium of ADB’s headquarters in Manila, Philippines. Up to 369 300-watt polycrystalline solar panels, occupying 716 square meters of roof space, convert sunlight into 110.7 kilowatts of electricity, enough to power 60 households.
The Third Atrium solar power plant is ADB’s second solar venture within its premises, and followed the same process as the development of its first rooftop solar power project in 2012: (i) site assessment, whether the roof can support the weight of the structure and is accessible to carry out installation and maintenance; (ii) shading analysis, whether adjacent buildings will cast shadows that affect the efficiency of the panels; (iii) array configuration, determining the panel orientation or tilt angle that most effectively captures the optimal annual solar irradiance; (iv) structural support, how solid the framing system is to withstand the highest earthquake intensity and wind speed; and (v) wiring design, determining the connection route to the main electrical system and establishing electrical safety precautions.
Installation brought additional insights. When constructing a new building like the Third Atrium, it is advisable to early on include the solar system design with the roof plan to accurately determine anchor points for pedestals that secure the mounting system. While the building itself was constructed with the end view of having another solar power plant in place, it nevertheless required additional concrete pedestals to the predetermined anchor points integrated into the roof to meet all structural requirements of the new solar power plant design.
Being situated atop a 9-storey structure, the system is quite exposed to the elements, especially strong winds. And with the country’s experience with Typhoon Haiyan, it is a must that the framing system and solar panels can withstand winds as strong as 270 km/h. Even the array configuration allowed spaces between the panel tables to cut off approaching wind. Also, by integrating the mounting system into the roof slab, the waterproofing is not compromised.
It is also recommended that an organization conduct its own research, benchmark against similarly inclined establishments, and familiarize itself with the solar photovoltaic (PV) system market. Gaining adequate knowledge on the market players will aid negotiations with the supplier, and give a good idea if the offer is fair and reasonable.
For both plants, ADB has a Design-Build-Operate-Transfer contract with a solar PV system provider which charges a fixed kW/h price for a certain period of time. At the end of the contract, both plants will be handed over to ADB at no cost. In contrast to the first solar project, ADB pays a much lower kW/h price and has a shorter contract term for the Third Atrium installation due to advancements in solar technology that have led to better efficiencies. By now, electricity from PV costs almost the same as electricity from the grid.
This particular model does not require an organization to make heavy capital investments. Capital investment is shouldered by the PV system provider, who is basically given the roof space for the agreed time of operating the solar power plant. Since project funding is stretched over the contract period, it can be treated as utility expense under the administrative budget. In the case of ADB, not only does it make good use of available roof space, it also showcases an energy source that supports its Leadership in Energy & Environmental Design green building certification program’s standard for sustainable energy on site. Furthermore, it helps to promote solar energy through regular study and benchmarking visits from companies and institutions in the Philippines and in ADB’s developing member countries.
The success of ADB’s first solar venture within its premises has shown that harnessing power from the sun is indeed feasible, and with the second, that it can be replicated. It is projected that in its first year alone, the Third Atrium rooftop solar power plant will generate 120,380 kW/h. Reduction in carbon footprint is estimated to be at 60.2 metric tons of carbon emissions per year.