**3. Installation of experimentalequipment**

The integrated solar energy panel proposed in this research consists of shielding and solar panels. Initially, the experimental room is only equipped with the proposed shielding panels for comparing variations of the room temperature, humidity, and energy consumption of air conditioning before and after installing the shield panels. Solar energy panels are then installed for studying the performance and efficiency of solar photocells made of different materials under various environmental conditions, comparing the effectiveness of solar photoelectrical systems equipped with or without the battery module, analysing the various methods to connect the current converters, studying the influence of solar panel installation angles on the efficiency under direct sunshine or solar radiation.

The experimental site is located in Tainan City, Taiwan; the experimental installations are shown in Figures 4 and 5. The solar panel system is mounted on an existing building in order to evaluate on-site the system's efficiency under natural solar illumination conditions. The evaluation is also carried out using a system facing east, south, and west so that annual performance and efficiency of the solar system proposed in this research can be assessed.

**Figure 4.** Final Photo of experimental installations in test filed

**Figure 5.** Final Photo of experimental installations with Integrated Photovoltaic and Sunshading Board

#### **4. Results and discussions**

#### **4.1. Advantages of sunshading board for energy-saving of building**

Temperature differences of the experimental building before and after installing sunshad‐ ing board and then the solar panel were recorded. The actual effectiveness of shading board was evaluated by comparing the indoor room temperature and the shaded spot tempera‐ ture with the outside temperature in order to monitor the savings on air conditioning energy consumption.

The temperature monitoring programme started one year before the installation of shading boards and lasted for three years; the results obtained during the hottest August and Septem‐ ber were used for evaluating the cooling effectiveness. The temperature sensors were installed on the balcony of the building so that the temperature measurement was not affected by direct sunshine or precipitation.

Energy consumption for cooling was recorded with three digital wattmeters from 8:00 am till 5:00 pm. The daily energy consumption was accumulated to yield the monthly consumption, and the following formula was used to estimate the energy savings:

**Figure 4.** Final Photo of experimental installations in test filed

150 Solar Radiation Applications

**4. Results and discussions**

**Figure 5.** Final Photo of experimental installations with Integrated Photovoltaic and Sunshading Board

Temperature differences of the experimental building before and after installing sunshad‐ ing board and then the solar panel were recorded. The actual effectiveness of shading board

**4.1. Advantages of sunshading board for energy-saving of building**

$$\text{Percent of Energy Savings} = \frac{\text{Reduction of Watts}}{\text{Yearly Watts}}\% \tag{1}$$

The on-site experimental results obtained with three experimental rooms are shown in Figure 6. The room equipped with a shading board shows lower temperature of 2.6°C to 2.7 °C in August and 1.8° C to 2.1 °C in September.

**Figure 6.** The temperature variation of various test rooms before and after they were equipped with a shading board

Figure 7 shows the analyses on energy consumption in August and September for the three rooms. Savings on air conditioning energy air consumptions for the two-year study period were 9.17% to 31.95% in August and 18.30% to 29.05% in September.

**Figure 7.** The power consumption in August and September for the three rooms before and after they were equipped with a shading board

#### **4.2. Energy efficiency for solar panels installed at various angles**

The efficiency of solar panels in stalled at various angles — 15°, 25° and 30°, — was carried out using the polycrystalline silicon and monocrystalline silicon panels in Systems I and III. These panels have different output rated values, so that the results are normalized by dividing the data by the output rated value of individual solar panels. As shown by the results in Figure 8, the solar panel with a 25° inclination has better energy output efficiencies than those 15o and 30o inclinations. Additionally, the performance of monocrystalline silicon panel is not signifi‐ cantly influenced by the angle of installation.

**Figure 8.** The comparison of the rated output efficiency of polycrystalline silicon and monocrystalline silicon panels

#### **4.3. Solar panel surface clarity and energy efficiency**

0

cantly influenced by the angle of installation.

2.5

0

0.5

1

1.5

Solar Energy Panel Yield (H/d**)**

2

Room 1

Room 2

Room 3

**4.2. Energy efficiency for solar panels installed at various angles**

Total

Power Consumption

Aug. Sep.

15° 25° 30°

Various Angles

**Figure 8.** The comparison of the rated output efficiency of polycrystalline silicon and monocrystalline silicon panels

Room 1

Room 2

**Figure 7.** The power consumption in August and September for the three rooms before and after they were equipped

The efficiency of solar panels in stalled at various angles — 15°, 25° and 30°, — was carried out using the polycrystalline silicon and monocrystalline silicon panels in Systems I and III. These panels have different output rated values, so that the results are normalized by dividing the data by the output rated value of individual solar panels. As shown by the results in Figure 8, the solar panel with a 25° inclination has better energy output efficiencies than those 15o and 30o inclinations. Additionally, the performance of monocrystalline silicon panel is not signifi‐

Room 3

Total

before installeation sunshading board

After installation sunshading board (1st year)

After installation sunshading board (2nd year)

monocrystallines silicon

polycrystallines silicon

300

600

900

kWh

with a shading board

152 Solar Radiation Applications

1200

1500

Improving the solar panel energy efficiency by cleaning the solar panel was undertaken to study the energy output efficiency for the non-crystalline, monocrystalline, and polycrystalline solar panel with and without the emulated rainfall. The weather in Taiwan is rather humid; the dust in the air is thus easily moistened, adhered to and accumulated on the solar panel,s surface to interfere with the solar panel's energy efficiency. On-site observations reveals that raindrops were somewhat effective in cleaning the solar panel surface. Hence, a water spraying system was installed above the solar panel and operated once every week to study the effectiveness of cleaning by rainwater. The results are shown in Figure 9.

**Figure 9.** The comparison of the energy output efficiency for the non-crystalline, monocrystalline, and polycrystalline solar panel

Without the water spray cleaning system, the polycrystalline solar panel produces 3.7% more energy than the monocrystalline solar panel. Providing the water spray cleaning system, however, causes the solar panels to produce more energy: 17.72% for the polycrystalline solar panel, and 5.38% for the non-crystalline solar panel.

A BIPV building will lower the indoor temperature by 1.8-2.7 °C during summer to save 9.17% to 31.95% of energy in cooling the building. The solar panel used in the BIPV building is made of monocrystalline silicon with a 25° inclination oriented westerly in order to obtain the maximum energy generating efficiency. The variation of ambient temperature may cause the electricity generation to vary by 0.07–4.5%; clear ambient air will assist in elevating the power generation by 3.7% to 29%. The overall experimental results revealed that the order of improved energy efficiency using water spray cleaning is monocrystalline solar panel, noncrystalline solar panel, then polycrystalline solar panel.

The energy output for solar panels before and after cleaning at various ambient temperatures are listed in Tables 1 and 2. The results in each table indicated that the clarity of solar panels affects the efficiency of solar panels made of different materials; dirty solar panels will lower the efficiency of producing electricity by 3.7% (Table 1) to 29.29% (Table 2).


**Table 1.** Solar panel energy output for panel before and after cleaning.


**Table 2.** Solar panel surface clarify and temperature before and after cleaning.

Hence, maintaining a clear solar panel surface by washing with natural raindrops or artificial water spraying system will assist in promoting the energy efficiency of the solar panel. The cleaning will lower the surface temperature of solar panels; but the temperature variation caused by cleaning the solar panel will result in decreasing energy efficiency slightly of only 0.07% (Table 1) to 4.53% (Table 2).

#### **5. Conclusions**

Various factors such as the solar panel's material, inclination angle, natural cleaning by rainwater and climatic conditions, among many others, may affect the solar panel's energy efficiency. Additionally, how the solar panel can be integrated with the shell of a building so that the combination will become a reliable source for cheap energy to provide air conditioning for the building is also the ultimate goal of this research.

The research results confirm that installing solar heat shading boards will lower the indoor temperature by 1.8o C to 2.7°C, save about 9.17% to 31.95% of energy consumption. As far as the solar panel's material is concerned, the monocrystalline panel is better than non-crystalline solar panel, which is better than polycrystalline panel. The order of magnitude for the panel installing angles is 25°>20°>30° with west-orientation being the most favorable for energy production, followed by south-orientation and east-orientation.

Maintaining a clean solar panel surface by washing will reduce the panel surface temperature to lower the energy output by 0.07% to 4.57%; however, this action will improve the energy output by 3.7% to 29%. In summary, installing the shading board will reduce the energy consumption for air conditioning. Raising the energy efficiency of solar panels, and developing new solar panel technology and implementation methods will effectively alleviate the peak power demand, improve the balance of power consumption, and promote the development and reuse of renewable energy sources.

## **Acknowledgements**

Generated power output (kW) After cleaning

> Earlier stage

silicon 1.31 1.59 1.64 1.48 12.98 1.44

silicon 1.08 1.13 1.09 1.12 3.70 0.07

Generated power output (kW) After cleaning

> Earlier stage

silicon 1.40 1.63 1.71 1.81 29.29 4.53

silicon 1.20 1.21 1.29 1.29 7.17 1.74

Hence, maintaining a clear solar panel surface by washing with natural raindrops or artificial water spraying system will assist in promoting the energy efficiency of the solar panel. The cleaning will lower the surface temperature of solar panels; but the temperature variation caused by cleaning the solar panel will result in decreasing energy efficiency slightly of only

Various factors such as the solar panel's material, inclination angle, natural cleaning by rainwater and climatic conditions, among many others, may affect the solar panel's energy efficiency. Additionally, how the solar panel can be integrated with the shell of a building so that the combination will become a reliable source for cheap energy to provide air conditioning

The research results confirm that installing solar heat shading boards will lower the indoor

C to 2.7°C, save about 9.17% to 31.95% of energy consumption. As far as

Later stage

Later stage

C) (38 <sup>o</sup>

C) (44 <sup>o</sup>

Clear degree

Clear degree

C) (%) variation (%)

C) (%) variation (%)

Real temperature

Real temperature

Item

154 Solar Radiation Applications

Polycrystalline

Non-crystalline

Item

Polycrystalline

Non-crystalline

System (38 <sup>o</sup>

0.07% (Table 1) to 4.53% (Table 2).

**5. Conclusions**

temperature by 1.8o

System (44 <sup>o</sup>

Before

**Table 1.** Solar panel energy output for panel before and after cleaning.

Before

cleaning During

**Table 2.** Solar panel surface clarify and temperature before and after cleaning.

for the building is also the ultimate goal of this research.

C) cleaning (34 <sup>o</sup>

cleaning During

C) cleaning (30 <sup>o</sup>

This work was partially supported by CPAMI of R.O.C. The authors wish to thank Professor Chen Jiann-Fuh form NCKU for many helpful suggestions during the course of this work.

#### **Author details**

Wen-Sheng Ou

Address all correspondence to: wsou@ncut.edu.tw

Department of Landscape Architecture, National Chin-Yi University of Technology, Taichung, Taiwan

#### **References**


**Chapter 8**
