About the optimization of photovoltaic power generation costs

This paper will establish a cost calculation model for distributed photovoltaic power generation, and analyze the cost of photovoltaic power generation and its influencing factors, including the impact of unit installed cost on cost electricity price, the impact of annual full-load power generation time on cost electricity price, and the impact of investment payback period on cost electricity price. , the impact of operation and maintenance fees on the cost of photovoltaic power generation, and the analysis of photovoltaic power generation costs and investment benefits at this stage.

Distributed photovoltaic power generation cost calculation model

The cost composition of photovoltaic power generation is shown in Figure 1.

Figure 1 - Schematic diagram of the cost composition of photovoltaic power generation — Figure 1 – Schematic diagram of the cost composition of photovoltaic power generation

In the formula, C is the cost of solar photovoltaic power generation, Yuan/kw h: Ckw is the construction cost of the power station, Yuan/kWp: WP is the power generation power of the power station under the standard peak irradiation, kWp: Cm is the annual operation and maintenance fee, Yuan; n is the operation time of the power station: h is the standard peak irradiation time converted from the local annual solar irradiation, h/a, the standard peak irradiation time in different parts of the world can generally be found, and the standard peak irradiation intensity is 1000/m2; f is the system output power coefficient %; W is the average generated power after the power station runs for a certain period of time considering the attenuation of the system, kW, which can be obtained through the attenuation coefficient of the generated power.

Analysis of the cost of photovoltaic power generation and its influencing factors

(1) Influence of unit installed cost on cost electricity price
According to the payback period of 20 years, the loan ratio is 80%, the loan interest rate is 7%, and the operating expenses are 2%. Assuming that the local annual full-load power generation time is 1500h, the cost corresponding to different unit installed costs calculated by CFD economic evaluation software is shown in Table 1.

Table 1 - Electricity Price Table — Table 1 – Electricity Price Table

(2) The impact of the annual full-load power generation time on the cost electricity price is calculated according to the payback period of 20 years, the loan ratio is 80%, the loan interest rate is 7%, and the operating cost is 2%. Assuming that the unit installed cost is 12,000 yuan/kW. The cost electricity prices corresponding to different full-load power generation times are shown in Table 2.

Table 2 - Different full-load power generation time cost tariff table — Table 2 – Different full-load power generation time cost tariff table

It can be seen that the annual full-load power generation time has a great impact on the cost of electricity prices. Usually, the annual full-load power generation time is directly related to the sunshine time. However, the design method of the power station system, system parameters, and whether the system follows the sun or not have a great impact on the annual full-load power generation time. For example, in an area with an annual sunshine time of 2800h (the vast majority of Northwest my country is such an area). The annual full-load power generation time of the fixed bracket is 1456h, but if all the sun-seeking system is adopted and the power optimization module is added, the annual full-load power generation time can reach 1808h. Of course, the increase of the annual full-load power generation time requires an increase in investment. But in the case of the same components, the additional investment is still economical. For sun-tracking brackets, etc., in addition to the one-time investment, local climatic conditions and installation conditions should also be considered. For example, the roof is usually not suitable for installing a sun-tracking system. For ground power stations with frequent strong winds, the maintenance cost of the tracking bracket may be large.

(3) Influence of payback period on cost electricity price
Assuming that the unit installed cost is 12,000 yuan/kW, the operating cost is 2%, and the annual equivalent full-load power generation time is calculated as 1500h. Under the two loan conditions, the cost electricity prices corresponding to different investment payback periods are shown in Table 3.

Table 3 - Cost electricity price table corresponding to different payback periods — Table 3 – Cost electricity price table corresponding to different payback periods

It can be seen that if all self-owned funds are used and the payback period is set at 25 years, the current cost of photovoltaic power generation is only 0.48 yuan/kw·h, which is already lower than the on-grid price of thermal power in many places. However, if the payback period is set to 5 years, the cost of electricity will be as high as 1.76 yuan/kw·h. Therefore, the setting of the payback period has a huge impact on the cost of photovoltaic power generation.

(4) The impact of operation and maintenance fees on the cost of photovoltaic power generation
The unit installed cost is set at 12,000 yuan/kw. According to the payback period of 20 years, the loan ratio is 80%, and the loan interest rate is 7%. The annual equivalent full-load power generation time is 1500h, and the cost electricity prices corresponding to different operating expenses are shown in Table 4.

Table 4 - Cost electricity price table corresponding to different operating expenses — Table 4 – Cost electricity price table corresponding to different operating expenses

It can be seen that the impact of operating expenses on the cost of photovoltaic power generation is also greater. For the same power station, if the operating cost is controlled at 1%, the cost electricity price can be 0.87 yuan/kw·h; and if the cost is controlled at 5%, the cost electricity price will soar to 1.51 yuan/kw·h. Operation and maintenance costs must be carefully calculated.

(5) Analysis of the cost and investment benefit of photovoltaic power generation at the current stage
The cost of photovoltaic power plants is basically stable, except that the prices of photovoltaic modules and inverters are greatly affected by the market, and other costs such as transformers, high and low voltage switchgear, electrical secondary equipment, cables, civil works and installation works are basically stable. See Table 5 for the analysis of the cost of photovoltaic power plants using fixed-installation polysilicon photovoltaic modules.

Table 5 - Cost table of photovoltaic power station with fixed installation of polycrystalline silicon photovoltaic modules — Table 5 – Cost table of photovoltaic power station with fixed installation of polycrystalline silicon photovoltaic modules

According to the National Development and Reform Commission’s on-grid tariff policy for photovoltaic power plants, photovoltaic power plants built after 2012 will implement a tax-included on-grid tariff of 1 yuan/kw·h. According to the previous analysis, the current cost of photovoltaic power plants is 12.02 yuan/w. Take a 10MW photovoltaic power plant as an example , the total investment of the project is 240.8 million yuan, calculated with the CFD wind power engineering economic evaluation software, the financial indicators of the photovoltaic power station are: the total profit of power generation is 285.468 million yuan, the investment recovery period is 10.37 years, the internal rate of return on all investment is 8.63%, and its own funds Internal rate of return is 12.65%.

Costing software

According to the above calculation model, the cost calculation and analysis software of solar photovoltaic power generation is compiled by using VC# program. The software is written in C# language, and the main interface is a window, which is divided into three parts, including geographic information input, electric field data input and calculation result feedback. Start interface.
The user enters the corresponding data to obtain the four output quantities provided. Only numbers can be entered in the input text box, and the program will continue to calculate only after all the data have been provided correctly, otherwise the user will be prompted to complete the information. When all the data are entered correctly, click the Calculate button to get the result.

This software can be used to estimate the construction cost and power generation cost of solar photovoltaic power plants, and it is more convenient to analyze the impact of changes in different parameters such as cell thickness, “cutting kerf thickness”, “photoelectric conversion efficiency” and raw material cost on the construction cost and power generation cost of photovoltaic power plants. , when using this software, every data input and calculation will be saved in the file, and every time the software is started, the last retained data in the file will be called. The above models and software tools can be used to determine the cost of photovoltaic power station construction and photovoltaic power generation. Analytical calculations are carried out, especially the influence trends of different factors such as cell conversion efficiency, raw material cost, silicon wafer thickness, and irradiation intensity level can be analyzed.