photovoltaic power generation.docx

Advanced Building Environmental Engineering and Building Services

3.3 Photovoltaic Power Generation

Photovoltaic power generation is a system that supplies the electricity consumed in a house by generating electricity using sunlight during the day.

3.3.1 Purpose and key points of photovoltaic power generation

1. The amount of photovoltaic power generation largely varies depending on the weather and time of the day.

2. Photovoltaic power generation provides the largest amount of power generation during the daytime in the summer when the load at power stations is in the highest and sells the surplus electricity.

3. The amount of power generation also depends on site condition such as duration of shady hours4. Photovoltaic power generation system distributors generally set a design life of approximately 15

years for power modules and approximately 10 years for power conditioners and provide approximately 10 years of warranty for the entire system.

3.3.2 Energy Conservation Target Levels for Photovoltaic Power Generation

Level 0 No photovoltaic power generation Level 1 Reduction in annual energy consumption up to 33.7 GJ(approx. 3kW of solar cell capacity )Level 2 Reduction in annual energy consumption up to 45.0 GJ(approx. 4kW of solar cell capacity )

3.3.3. Photovoltaic Power Generation

1. Regional solar radiation level

Japan

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Indonesia

2. Direction of installation and tilt angle

The sunlight utilization efficiency depends on the installation direction and tilt angle of photovoltaic panels, but it is also depends largely by the latitude of the building site. In low altitude regions, the roof pitch and direction can be relatively flexible designed, as long as a sharp tilt angle is avoided, and it may be possible to install photovoltaic panels on the roof of preferred design.

In zone 6, for example Naha, utilization efficiency is 100% (due south), 94-95% (east or west) and 88% (north). In addition, the higher annual power generation might be achieved when the tilt angle is 20o in south side roof.

On the other side, in Zone 5 for example Miyazaki, the utilization efficiency is 100% (south), 82-85% (east) or west and 64%(north). The highest efficiency for the tilt angle is 30%.

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3. Local conditions

The outside brightness of the direct solar radiation on a sunny is at least 15000 lux, with 7000-800 lux on a cloudy day and approximately 3000 lux in the shade.

Future development plans for the surrounding area should also take into consideration.

4. Cautionary Advice on installing photovoltaic panels

When installing photovoltaic panel on the roof in regions with heavy wind, caution required to prevent damage caused by storm.

In region where the salt damage is a concern, rustproof of metal parts such as frame and bolt are essential.

3.3.4 Test calculation of photovoltaic power generation cost

Power generation simulation was performed and calculation was conducted for Naha (Zone V) and Miyazaki (Zone VI) in order to determine the number of years it will take to recover the initial cost of installation.

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1. Calculation test result for Naha

2. Calculation test result for Miyazaki

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3.4 Solar Heat utilization methods for zone V

The basic of reducing heating energy are to decrease heat loss from building, and also increase heat gained by the building.

A method for obtaining natural heating effect using solar heat in a building called passive solar heating.

3.4.1 Purpose and key points of solar radiation heat utilization.

1. Used to reduce heating energy consumption in winter2. Solar heat radiation gain and utilization can be achieved using the three methods: increasing

the amount of heat gain (heat collection), controlling heat gain loss (insulation) and effective utilizing heat gain while preventing a decrease in room temperature(heat storage)

3. Major component that obtain solar radiation heat are glass windows opening. But, glass windows are also easy to lose the heat because it has high solar transmittance.

3.4.2 Energy conservation target levelsA. The Target Levels

Level 0 Heating energy reduction rate: noneLevel 1 Heating energy reduction rate: approx. 5%Level 2 Heating energy reduction rate: approx. 10%Level 3 Heating energy reduction rate: approx. 20%Level 4 Heating energy reduction rate: approx. 40%

B. Requirement for achieving the target level1) Regional climate characteristic:

Passive solar zone classification (PSP) here is refers to the classification of regional solar radiation characteristic based on solar radiation level and temperature in winter. This categorizes Japan in 5 zones.

Zone A Very cold region with low solar radiation levelZone B Cold region with low solar radiation levelZone C Cold region with high solar radiation levelZone D Region with high solar radiation levelZone E Warm region with high solar radiation level

2) Site Condition (Influence of obstruction of sunlight)

There are three categories of site building according to the influences of obstruction:Table 1 Site Classification by influence of obstruction of sunlight

Classification Degree of obstruction of sunlight Guideline for sunshine hours (winter solstice)

Site 1 Site with large influence of obstruction of sunlight (approx. 50%) where solar radiation heat utilization is difficult

At least 3 hours

Site 2 Site with small influence of obstruction of sunlight At least 5 hours

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(approx. 25%) where solar radiation heat utilization is possible

Site 3 Site with no influence of obstruction (0%) where solar radiation of heat utilization is easy

Sunlight can received all day

How to check the sunshine hours

3) Building DirectionThe solar radiation heat gain and utilization is largely depend to the direction of the opening which serves as the heat collection area. It is effectives within 30o east or west of due south, regardless of the regional classification. If it exceed 30o from due south the heat collected from the opening drastically decreases.Therefore the direction of opening aims for heat collection must be within 30o of sue south

4) Methods for utilizing solar heat

Method 1 Insulation methods for opening (enhanced insulation performance of opening)

Method 2 Methods for collecting heat from opening (enlarged opening area for heat collection)

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Method 3 Heat storage method (use of heat storage material)

C How to achieve the target levels

Energy conservation target level for solar radiation heat utilization are determine by site condition (obstruction of sunlight), building direction, and the use for utilizing solar radiation

In order to achieved the target levels of solar radiation heat utilization with validated effectiveness, the following condition 1. Housing insulation level at least level 32. Opening area for heat utilization at least 10% ratio of opening area for heat collection to

the floor area (direction of the openings for heat utilization must be within 30o east or west of due south).

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3.4.3 Steps for examining solar heat utilization technology

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3.4.4 Solar Heat Utilization methods

Method 1. Insulation methods for opening (enhanced simulation performance of opening) The heat insulation of building openings is the most important things to me remind to secure the heat loss from the building.a. Points to note when choosing materials for opening

- Glazing specification Glazing is needed to increase heat gain and minimize heat loss. It is believe that the effective glassing should be with low heat transmission coefficient.

- Frame specification In order to enhance insulation of windows frame, the effective way is to make fitting and fixtures using wood, resin vinyl or other less heat conductive material with high insulation performance

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Method 2: methods for collecting heat from the openings (enlarge opening area for heat collection

- Although opening leads to significant heat loss, south facing opening have a positive daily heat balance and it is effective to enlarge opening area that serves as a heat collection area

Method 3: heat storage method (use of heat storage material)

- Heat storage technology prevent the overheating of the room by absorbing heat during the day and decrease the room temperature by releasing the absorbed and stored heat at night.

- Building component that are effective in heat storage includes floors, exterior walls and ceiling

- Furniture, equipment and other living necessities in house might also have the heat storage effect.

1. Materials of heat storage component

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It is appropriate to use material with the following characteristic for the heat storage devices:a. Having large heat capacity b. Being heat conductivec. Quick heat absorption and emission from the surface

The heat capacity can be obtained in the following formula:

Heat capacity (Kj/oC) = volume of heat storage component (m3) x volume specific heat storage material)Kj/m3.oC)

2. Requirement for heat storage components

3. Points to note when designing heat storage componenta. Position of the heat storage component

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Heat storage effect becomes more apparent if the heat storage component receives direct solar radiation and the amount of solar radiation heat increase.

b. Area of heat storage componentThe greater the area of heat storage component, the higher the heat storage effect

c. Thickness of heat storage component The heat storage component performance of material will not change if the thickness exceed the effective thickness.

3.4.5 Estimating effects of adopting solar radiation heat utilization methods1. Trial calculation methods

2. Detailed setting of methods

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3.5Solar Water Heating

3.5.1 Purpose and key points of solar water heating

- Heat sources of domestic hot water system can be obtained from gas, oil, electricity and natural energy

- The initial costs of solar water heating are high, but once the installation is completed, running cost can be dramatically reduced and appropriate installation enables the recovery of initial cost during the service life of devices.

- Heat collection section of solar water heating is the most significant influence on the amount of heat collection.

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- In hot humid regions which high number of solar radiation, a typical heat collection area of 3 – 4 m2 can cover more than half of the annual domestic hot water energy and solar water heating is an extremely effective energy saving methods

- Solar water heating devices are generally classified into “solar water heater” and “solar system”.

- Solar water heating devices require heavy heat collectors to be installed on the roof and some models need a hot water storage tank.

Number of years for recovering initial cost of solar water heating device.

Definition of term

Some terms used in the previous Design Guidelines for low energy housing with validated effectiveness (issued in June 2005) have been reviewed and revised to comply with name and definition employed by the Japanese Industrial Standard.

3.5.2 Energy Conservation Target Levels for Solar Water Heating.

1. Definition of Target Levels

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2. How to achieve the target levels

3.5.3 Steps for Examining Solar Water Heating and Prerequisites

1. Steps for examining the feasibility of adopting solar water heating

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2. Prerequisites 1) Local weather conditions

There is a possibility that solar heat cannot be sufficiently collected in the following regions: Regions with insufficient solar radiation Regions with severe winters Regions with high snowfall or snow cover

2) Surrounding conditions of the building sitesThere is a possibility that solar heat cannot be sufficiently collected in the following conditions: There are many adjacent building obstruct solar radiation on the roof There are many trees and other elements obstruct solar radiation on the roof

3) Building structures and others factorsIn the installation of solar water heating, the building structures and roof need to be designed by taking account to the weight of the devices, especially if it is integrated with hot water storage section.

3.5.4 Solar Water Heating Methods

Solar water heating devices can be classified into the following items in general:

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1. Heat collection system (direct or indirect heat collection)2. Heat collection medium (water, antifreeze solution, air and heat pipe)3. Heat medium circulating method (forced or natural circulation)4. Structure of heat collection and hot water storage section (integrated or

separated)5. Heat collection section shape (flat plate, vacuum tube, etc.)

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Method 1: Securing heat collection area and other considerations

1. Heat collection area.The most important factor in sufficiently collecting solar heat is to secure the large heat collection area.

2. Direction of installation and tilt angle of heat collection section Direction of installation - The heat collection section should be installed on the south side as much as

possible- The east sides is less effectives than the west side- The north side has hardly any effect.- It is necessary to locate with no shade from adjacent building or other elements in

the future.

Tilt angle- Generally, the maximum annual heat collection can be reached when the installation

angle (tilt angle) of heat collection section is 30 o C. However, since there is no significant difference in heat collection due to tilt angle in both hot and humid regions, please choose a tilt angle approximately 60oC by taking into account the roof pith. A frame is required when installing heat collector at an angle that is stepper than the roof pitch

-

Energy saving effect of heat collection area

1. In hot humid region, the 3-4m2 of heat collection area is recommended2. The typical hot water storage section is 200L, which appropriate for 4m2 of heat collection

area.

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Method 2 : Appropriate connection with auxiliary heat source

Method 2.a Not connecting with auxiliary heat source

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Method 2.b Connecting with auxiliary heat source using three way valve

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Method 2.c Connecting with auxiliary heat source using solar connection unit

Method 3: Adopting energy efficient circulating pump (photovoltaic power only)

The photovoltaic system requires a circulating pump which circulates the water and antifreeze solution if it is a force circulation types.

If the power consumption of circulating pump is high, energy performances declines. Therefore, it is necessary to choose a model that operate the pump only when needed, uses a low power consumption pumps, or operates the pump using solar cell power.

Conventionally, pump with power consumption of nearly 100 W have been commonly used, but, nowadays, there is a model with 20-65W operate the motor, which achieved more energy saving.

3.5.5 Solar Water heating Planning and Consideration for Use1. Consideration for sectional planning

a. Installing heat collector (wind protection) To prevent heat collector from being blown away by strong winds, it is effective

to fasten them as closely as possible to the roof and affix them a gentle angle (figure 4a). On the other hand, when using frame in order to adjust the direction, heat collector should be tightly fixed using wire or other means (Figure 4.b).

b. Installing hot water storage tank (separate type only) It is necessary to locate heat collector, hot water storage tank and water heater

as close as together as possible Hot water storage is recommend install indoors for less heat loss.

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Circulating pipes should as short as possible

2. Consideration for Coefficient operation and control methods

There several cautions to follow when using system which connects a solar water heating devices with an auxiliary heat source using a solar connection unit”

a. Preset temperature of water heater When using a solar connection unit, the auxiliary heat source communicate with the

solar connection unit via communication cable and hot water is discharged according to the preset domestic hot water temperature of the auxiliary heat source remote control

To increase the solar heat utilization rate, it is important to set domestic hot water temperature of the auxiliary heat source as low as possible.

b. Adequate control of auxiliary heat source In a system using a solar connection unit (method 2c) of the solar heat water

temperature is low than the preset domestic hot water temperature, it is reduce to the upper tap water temperature limit (30 to 35oC) by mixing with the domestic hot water and discharge it.

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3.5.6 Explanation of Solar Water Heating System1. Solar heat collection system + heat medium circulation method

The solar heat collection system is regarded as the most important element that largely dictate the structures and the characteristic of solar water heating devices.a. Direct heat collection type

The direct heat system is a system that directly send water to the heat collections panels where it is heated for domestic for domestic hot water.

b. Indirect heat collection typeIndirect system is a system that circulates the antifreeze solution instead of water between the heat collection section and the hot water storage section. The heat collection section collect heat while the hot water storage tank heat tap water using a heat exchanger located inside the hot water storage tank.

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2. Layout of heat collection and hot water storage section

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3. Shapes of heat collection section The flat type has a flat collection unit covered with insulation material on the

back and the transmission unit on the front. Heat collection efficiency 40-50% The vacuum tube type has a tubular heat collection unit that is protected by

tubular transmission unit and has vacuum gaps for reinforced insulation. Heat collection efficiency 50-60%.

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photovoltaic power generation.docx