Vertical Solar (Building Facades/Cladding)

Challenges Of Constructing Vertical Solar Systems On Building Facade

Solar PV Systems are commonly installed on the rooftops to generate energy for buildings. However, the capacity  of solar system to harness renewable energy for block services is currently limited by the space available on the building rooftops

Vertical Solar Photovoltaic (PV) on building facade or cladding can potentially overcome limitations caused by limited rooftop space and various authority regulation. With an additional façade allocated installation area, this greatly increase a building’s capability of generating electricity to meet the energy demands of the buildings and offers protection from the weather as well. The application of PV technology on vertical façade of the building is considered as an element of Building-Integrated PV. this would reduce the installations mostly to East-West facades where less or no windows are present. Due to the diurnal cycle, this will then also reduce the overall power generation as typically only one of the facades would be widely exposed to sun at a time.

 

Despite the potential benefits in Aesthetic design, Solar gain and lighting, it is difficult to optimize the performance of façade-mounted PV system in urban areas. The two bigger challenge of designing and developing such systems is to 1) minimize losses caused by shadows from nearby structures, 2) reduce the reflected light caused the Solar Glare issue. Careful planning is a crucial to building a Vertical Solar PV System that can overcome such challenges and maximize the energy generated by the system and Cost–effectiveness analysis (CEA) is also one of the main considerations.

 

Background

Fossil fuels such as natural gas and coal are limited. Given Singapore’s geographical size and lack of natural resources, solar energy is the most readily-available source of renewable energy in Singapore given the relatively high amount of sunlight we receive compared to the rest of the world. Solar Photovoltaic (PV) enables us to reduce our reliance on fossil fuels and ensure that we have an alternate source of energy that can mitigate the environmental impact of energy consumption, thereby enhancing our energy security.

Since 2009, the Housing and Development Board (HDB) has been test-bedding and implementing solar PV across HDB blocks. As the potential and demand for solar PV grows, HDB shifted from the early Supply and Install models in 2009 to Solar Leasing in 2011, which allowed a sustainable, larger-scale deployment of solar panels. The success of the Solar Leasing business model spurred the Whole-Of-Government SolarNova initiative to deploy solar panels large-scale across public buildings.

Upcoming

So far, HDB’s efforts in solar PV installations have been focused on rooftop spaces. This is because the rooftops are open spaces with relatively few structures or objects that may shade the panels, thus ensuring maximum exposure to sunlight throughout the whole day for maximum solar power generation. In addition, the rooftops are generally out of view from the public, hence issues such as glare and aesthetics are less of a concern.

While the earlier focus for solar PV deployment is largely on rooftops, the vertical planes present a great opportunity to stretch the solar PV potential further. This is especially so given that the amount of usable roof space is limited (e.g. shading from neighbouring block; rooftop design such as pitched roof that is technically difficult to install solar PV; competing services such as telco, green roof, etc competing for the rooftop space) and will be used up ultimately.

Given Singapore’s urbanised high-rise high-density environment, the façade areas far exceed the roof areas. If these façade areas can be utilised for solar energy generation, it will increase Singapore’s solar PV potential significantly. Hence, HDB is conducting further studies on how to optimise vertical solar PV installations to harness solar energy along the vertical faces of buildings.

The installations will allow HDB to assess the technological viability and performance of the system. The project thus presents an opportunity for HDB and the private sector to test-bed and showcase new urban solutions.

Vertical Solar PV System Requirement

The proposed vertical solar PV system shall consist of 3 main portions:
(i) Vertical panel mounting system
(ii) Solar PV Panels
(iii) Safety, Rergulation and Authorities Approval

Solar PV panels proposed may be rigid or flexible types. Types of solar PV panels may include, but not limited to, mono and polycrystalline silicon, and amorphous thin-film types, and may include coloured and non-coloured solar PV panels. Notwithstanding the 2 portions as detailed above, integrated solutions which combine solar panels as the mounting structure themselves (for example in the case of Building Integrated Photovoltaic, BIPV) are allowed. Other components necessary for the successful operation of the system, such as a monitoring system, inverters, trunkings, wirings etc shall be included as part of the vertical solar PV system.

Effectiveness of Design
Solar Energy Generation
Aesthetics
Application Potential

The solar PV panels and inverters, where applicable, shall be third party tested and certified to relevant IEC standards, such as IEC 61215, and IEC 61727.

The proposed vertical solar PV system shall adhere to the Singapore Fire Code 2013, in particular, but not limited to Section 3.5.7 on vertical fire spread. The Qualified Person (QP) will be required to obtain the Singapore Civil Defence Force’s (SCDF) approval for the proposed vertical solar PV solution.

Technical Competency

1. General Standards

Some specific standards or classification for Solar PV Panels to be mounted in Vertical facade or Cladding are to be established. The Solar PV Panels shall be third parties tested and certified to Relevant IEC standards such as IEC 61215, IEC 61727, IEC 61730-2. The fire safety requirements also apply.

2. Preliminary requirement for adhere to regulations

a. The proposed vertical solar PV System shall adhere to the Singapore Fire Code 2018

b. Solar panels are subjected to test under BS476 Part 6 & 7 standards

c. The Qualified Person (QP) will be required to obtain the Singapore Civil DefenceForce’s (SCDF) approval for the proposed vertical solar PV solution.

3. Components to be tested 

  • a. Solar Panels (Fire Tests to IEC 61730 / MST 23)
  • b. Junction Box
  • c. Solar cables
Energy Performance On Facade Photovoltaics
  • Module Charateristic
  • Climate-Oriented Design
  • Natural Daylighting ( Skylight)
  • Facade Envelope
  • Mountng Position
  • Shading
  • Optimising
  • Facade Thermal
  • Ventilation Air
  • Infiltrations