Rooftop BIPV Solar- multifunctional savingsLeak Proof New Design

• savingsduetomultifunctionalBIPV•GRIHA/LEEDcompliance• lowerlightingenergycost(10to20%)• lowercoolingenergycost(10to40%)• increasePV-suitablespaceonbuildings• increasedaesthetics• costsavinginregularrooftopmaterials• increasedNaturalLight(20to40%)•morepowerpersite• simplifiedinstallation• easiertomaintain(withpathways)

Installations of solar photovoltaic (PV) technologies on building rooftops are common in some parts of the world. The vast majority of these systems are composed of modules that are mounted off the surfaces of roofs using different types of racking hardware. System designs are most influenced by PV performance considerations, and aesthetics are often secondary.

But growing consumer interest in distributed PV technologies and industry competition to reduce installation costs are stimulating the development of multifunctional PV products that are integrated with building materials.

BIPV offers a number of potential benefits, and there have been efforts to develop cost-competitive products for more than 30 years.

BIPV is a multifunctional product (not a combination of independent products) that generates electricity and replaces traditional building materials by serving as a significant weather barrier on Factory / Office / Residential building surfaces.

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RooftopSolarPVSolutions

BIPVSolarSolutions-rooftop&elevation

BIPV Structural work

Description RegularSolarRooftop BIPVSolarRooftop AdvantageofBIPV

Rooftop

Solar PV - construct Glass + Tedlar + Aluminium backframe

Glass + Glass (PVB encapsulation)

More stronger (due to lamination) and offers

multiple benefits

Funtional - Benefits

• Protection against nature• Protection & Security• Enclosed Envelope• Solar Power Generation

• all the benefits• Improved Aesthetics• Heat reduction from Roof• Natural Light

comprehensive solution with more functional advantages

Aesthetics

Most of the times, the roof / rooftop loses its aesthetics and

spoil the entire look of the building / factory

Great Aesthetics and gives an integrated visual appeal

Better Real Estate Value - due to enhanced visual

appeal

Light Transparency Not Possbile Yes. 20 to 40 %More Natural Light - savings in Lighting Energy (as high

10 to 20 %)

UV & IR filtering Not available YesHeat reduction - so lower cooling cost - due to UV &

IF filter

Roof

Need metal sheet roofing Not needed Savings - since no metal sheet roofing needed

Seperate Structure for Metal sheeting Not needed Same as above

Perennial problem if leaking happens due to bolt holes Problem do not arise No costly break-downs & no

loss of productivity

Structure for PV

Another seperate structure needed for PV Mounting; also it should be atleast 2 to 3 feet

taller from the base structure - for maintenance

Integrated - Single & Simple structure

Savings on having an integrated structure

Electrical ConnectionsExternal - and clearly visible,

and sometimes become dangerous due to exposure

Electrical connections either will go inside the frame, or

will come along the frames in the interior side of the roof

Easier & Simpler to Service incase of any electrical

disjoint, etc.

Heat ReductionNothing by itself. Have to

have extra PUF / XPS / Thermocole padding etc

Can use a DGU construction (double glazing unit) having a spacer with air - cuts down 75

% of heat from the roof, still giving natural light

Savings in money due to reduction of heat upto 70%

through the roof

Install Capacity

Will waste more space per kW, since a seperate structure; also due to its positioning for

shadow-effects.

More kW per unit of area. since there is no space wasted

and no problem in shadow effects

Generation of more kWh per area - resulting in lower

State Electricity Board charges

Maintenance - hassles

Should have the PV structure with a minimum gap at least 3 feet high, so that a person

could go & do electrical maintenance or others

No problem - if with pathways on the structure - then even

cleaning is easier as like cleaning any Glass-Skylights

Easier, Less Costly and More Safety, when servicing &

maintenance.

The sun delivers its energy to us in two main forms: heat and light. There are two main types of solar power systems, namely, solar thermal systems that trap heat to warm up water, and solar PV systems that convert sunlight directly into electricity as shown in Figure.

When the PV modules are exposed to sunlight, they generate direct current (“DC”)electricity. An inverter then converts the DC into alternating current (“AC”) electricity, so that it can feed into one of the building’s AC distribution boards (“ACDB”) without affecting the quality of power supply.

Types of Solar PV SystemSolar PV systems can be classified based on the end-use application of the technology.There are two main types of solar PV systems: grid-connected (or grid-tied) and off-grid (or stand alone) solar PV systems.

Grid-connected (ON-Grid) solar PV systems

The main application of solar PV in Singapore is grid-connected, as Singapore’s mainisland is well covered by the national power grid. Most solar PV systems are installedon buildings or mounted on the ground if land is not a constraint. For buildings, they are either mounted on the roof or integrated into the building. The latter is also known as Building Integrated Photovoltaics (“BIPV”). With BIPV, the PV module usually displaces another building component, e.g. window glass or roof/wall cladding, thereby serving a dual purpose and offsetting some costs.The configuration of a grid-connected solar PV system is shown in Figure 2.

A building has two parallel power supplies, one from the solar PV system and the other from the power grid. The combined power supply feeds all the loads connected to the main ACDB. The ratio of solar PV supply to power grid supply varies, depending on the size of the solar PV system. Whenever the solar PV supply exceeds the building’s demand, excess electricity will be exported into the grid. When there is no sunlight to generate PV electricity at night, the power grid will supply all of the building’s demand. Agrid-connectedsystemcanbeaneffectivewaytoreduceyour dependence on utility power, increase renewable energy production, andimprovetheenvironment.

Off-Grid connected solar PV systems

Off-grid solar PV systems are applicable for areas without power grid. Currently, such solar PV systems are usually installed at isolated sites where the power grid is far away, such as rural areas or off-shore islands. But they may also be installed within the city in situations where it is inconvenient or too costly to tap electricity from the power grid. For example, in Singapore, several URA parking sign lights are powered by off-grid solar PV systems. An off-grid solar PV system needs deep cycle rechargeable batteries such as lead-acid, nickel-cadmium or lithium-ion batteries to store electricity for use under conditions where there is little or no output from the solar PV system, such as during the night, as shown in Figure 3 below.

Solar PV System - an Overview

This section gives a brief description of the solar PV technology and the common technical terms used. A solar PV system is powered by many crystalline or thin film PV modules. Individual PV cells are interconnected to form a PV module. This takes the form of a panel for easy installation.

PV cells are made of light-sensitive semiconductor materials that use photons to dislodge electrons to drive an electric current. There are two broad categories of technology used for PV cells, namely, crystallinesilicon, as shown in Figure 4 which accounts for the majority of PV cell production; and thin film, which is newer and growing in popularity.

Crystalline cells are made from ultra-pure silicon raw material such as those used insemiconductor chips. They use silicon wafers that are typically 150-200 microns (onefifth of a millimetre) thick. Thinfilm is made by depositing layers of semiconductor material barely 0.3 to 2 micrometres thick onto glass or stainless steel substrates. As the semiconductor layers are so thin, the costs of raw material are much lower than the capital equipment and processing costs.

Apart from aesthetic differences, the most obvious difference amongst PV cell technologies is in its conversion efficiency, as summarised in Table 1. For example, a thin film amorphous silicon PV array will need close to twice the space of a crystalline silicon PV array because its module efficiency is halved, for the same nominal capacity under Standard Test Conditions1 (STC) rating.

For crystalline silicon PV modules, the module efficiency is lower compared to the sum of the component cell efficiency due to the presence of gaps between the cells and the border around the circuit i.e., wasted space that does not generate any power hence lower total efficiency.

Effects of Temperature

Another important differentiator in solar PV performance, especially in hot climates, is the temperature coefficient of power. PV cell performance declines as cell temperature rises. For example, in bright sunlight, cell temperatures in Singapore can reach over 70ºC, whereas PV modules are rated at a cell temperature of 25ºC. The loss in power output at 70ºC is therefore measured as (70 - 25) x temperature coefficient. Most thin film technologies have a lower negative temperature coefficient compared to crystalline technologies. In other words, they tend to lose less of their rated capacity as temperature rises. Hence, under Singapore’s climatic condition, thin film technologies will generate 5-10% more electricity per year.

Solar PV Technology

Mono-Crystalline

Poly-Crystalline

Thin - Film

Solar PV Output Profile

Solar PV only produces electricity when sunlight is available. The output of a solar PV system varies with its rated output, temperature, weather conditions, and time of the day. The power output profile of the PV installation as shown in Figure, at a selected test site in Singapore collected over a period from 2002-2004, in terms of its capacity factor[2] , shows a high variation of solar PV output.

[2] PV Output capacity factor = Ratio of the actual output of the PV installation at time (t) over its output if it had operated at full rated output.

The amount of electricity you are able to generate from a solar PV system depends not only on the availability of sunshine but also on the technology you choose to install. For example, a typical 10-kW rooftop solar PV system in Singapore would produce about 11,000 to 12,500 kWh annually using crystalline PV modules, and 12,000 to 14,500 kWh annually with amorphous silicon thin film PV modules.

Operations of Solar PV Systems

The most practical indicator of the performance of the solar PV systems can be obtained from the remote monitoring and data logging software supplied by most inverter manufacturers. The data logging software will record daily, monthly, and annual output for comparison of the actual system performance against the expected system performance. See Figure for typical performance monitoring displays.

It is recommended that preventive inspection and maintenance works are carried out every six to twelve months. The PV modules require routine visual inspection for signs of damage, dirt build-up or shade encroachment. Solar PV system fixtures must bechecked for corrosion. This is to ensure that the solar PV system is safely secured.

While the inverter’s functionality can be remotely verified, only on-site inspection can verify the state of lightning surge arrestors, cable connections, and circuit breakers. The following table shows some recommendations on the preventive maintenance works on the components and equipment, and the corresponding remedial actions to be carried out by qualified personnel.

BIPV Solar PV Glazing Maintenance

Components Description Action

Water-Proof Sealing

of the BIPV and

Structure

• check structure for physical wear & tear

• check for sagging / deformation

• check for damage in the seal / sealant

• check for rain water seepage

• if, then give support / reweld / paint

• if, then give support / reweld

• if seepage, recommend deseal & reseal

• if, recommend deseal & reseal

P V Modules

• check for dust / debris on surface of P V

Modules

• Check for physical damage of PV panel

• for Loose cable connection between PV

modules, PV arrays, etc

• for cable conditions

• Wipe Clean. Do not use any solvents other

than Water

• Recommend replacement if found damaged

• Retighten Connections

• Replace cable if necessary

Solar Inverter

• check Functionality - automatic

disconnection upon loss of grid power

connection

• check ventialation condition

• for Loose cable terminations

• for abnormal operating temperature

• Recommend replacement if functionality fails

while testing

• clear dust & dirt in ventilation system

• tighten connections / terminations

• recomment replaements

Cabling

• check for cable conditions - wear & tear

• check cable terminals for burnt marks, hot

spots or loose connections

• Replace cable if necessary

• Tighten connections or recommend replace-

ments

Junction Boxes

• check cable terminations - wear & tear or

loose connections

• check for warning notices

• check for physical damages

• tighten or recommend replacement

• replace - when - warning notice if need-be

• recomment replacementElectrial Isolation • check functionality • if found defective - recommend replacement

Silicone structural glazing is a method utilizing a silicone adhesive to attach glass, metal, or other panel material to the structure of a building.

Windload and other impact loads on the façade are transferred from the glass or panel, through the structural silicone sealant to the structure of the building. The silicone sealant must maintain adhesive and cohesive integrity as the façade is subjected to windload and thermal stresses.

Structural glazing (SG) is a high performance application and not all silicone sealants are suitable for this application. Only silicone sealants which have been developed and tested specifically for structural glazing applications should be used.

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