How to take the tilt angle of the roof photovoltaic power station?

What is the inclination angle of the photovoltaic power plant square array of concrete roof? Is it based on the solar radiation situation of different regions to select the best inclination angle or lower the inclination angle? Under the same roof with different inclination angles, the photovoltaic capacity can be developed, total power generation during operation, investment income What kind of changes will happen? Here's an example of a rooftop project in Beijing.

I. Resources

Taking the weather station in the southern suburb of Beijing, which is 6km away from the project site, as the reference weather station, the total solar radiation is 4943.3MJ/m2.

Figure 1: Bar chart of monthly changes in total solar radiation from 1983 to 2012 in Beijing

Second, the power station

The roof of the project is a concrete flat roof with a total area of ​​approximately 17,300 square meters, and the actual area where photovoltaic panels can be disposed is approximately 6,200 square meters. All are surrounded by industrial plants, no tall buildings block, good construction environment.

The project selected 260Wp photovoltaic modules, 20 components in series into a branch, the components placed in a vertical row.

Figure 2: Roof plan

Third, the total amount of radiation on the slope

The total amount of total solar radiation on the inclined plane when the inclination angle is 0 to 40 is calculated using the total radiation value of each month, as shown in the following figure. When the tilt angle is 31°, the total amount of radiation on the inclined plane is the largest. That is, the optimum angle of inclination is 31°.

Figure 3: Total amount of radiation on inclined planes at different inclination angles

IV. Comparison of installed capacity and full-time hours

The area of ​​the photovoltaic module that can be installed on the roof is limited. The larger the angle of inclination is, the larger the space between the front and back of the square is, and the smaller the installable capacity is, the lower is the installation capacity and the number of full-time hours from 0° to 31° every 5°.

Table 1: Comparison of installation capacity and full-hour hours under different inclination angles

From the above table, it can be seen that with the increase of the tilt angle of the photovoltaic array, the array spacing increases, and the installed capacity decreases accordingly, but it is not a certain proportion. This is because the actual usable area of ​​the roof on the project is not regular, and there are some It is caused by the structure that needs to be avoided.

V. Comparison of investment income

1 Comparison Precondition

Investment level is 9 yuan/W; capital is 20%, 80% bank loan; long-term bank loan interest rate is 5.9%, short-term is 5.35%; on-grid electricity price is 1.1431 yuan/kWh in 1~20 years, and 0.7651 yuan in 21~25 years. /kWh calculation.

2 analysis results

Table 2: Comparison of Project Benefits at Different Dip Angles

Through comparison, it is found that the best payback period is the shortest payback period and the highest internal rate of return. As the tilt angle decreases, the payback period gradually increases and the internal rate of return gradually decreases. The financial net present value gradually increases at a tilt angle of 31° to 10°, reaches a peak at a tilt angle of 10°, and drops back at a tilt angle of 5°.

In summary, how to take the tilt angle of the roof photovoltaic power station depends on the purpose of the power station construction. If it is to satisfy its own power consumption and pursue a quick return on investment, it is possible to choose the best inclination type installation. If you want to generate as much electricity as possible within a limited roof area, and the absolute value of the project's revenue is high, you can lower the inclination appropriately, but it is not as good as it is lower.

In this paper, only one design scheme—the vertical arrangement of components in a single row—has been comparatively analyzed. When comparing the actual design, multiple schemes should be compared. The optimal design of the photovoltaic array cannot be neglected due to the small scale of the rooftop photovoltaic power plant.