1、光伏系统发电成本分析

光伏发电具有初投资成本高、运营维护成本低的特点，在光伏发电经济性分析中，成本和效益应当指在光伏系统寿命周期内的总成本和总效益。政策性补贴是必须计入分析过程的一个重要因素，可以抵消一部分并网光伏系统建设成本。

并网光伏发电系统的寿命周期成本=投资成本＋运营维护费－补贴，并网光伏系统投资成本，包括光伏组件、蓄电池，逆变器、配电柜、支架、电缆等设备和材料购置费，还有工程建设费和交通运输费；运营维护费包括运营人员工资、逆变器等电气设备维修费、光伏组件清洗费等，光伏系统运营期一般为20-30年；光伏系统建设和运营期内享受的政策性补贴总额。与燃煤燃油发电需要购置、运输、储存能源以及处理残余物的情况不同，光伏系统的输入能量来自太阳，在运营期内光伏系统不需要其他能源，也几乎不产生残余物。如果光伏阵列采用固定式安装，则光伏系统中没有易损的旋转部件，而组件等主要电气设备使用寿命均在20年以上，系统的维护工作量也很小。因此光伏系统的运营维护成本明显低于传统发电系统的运营维护成本。

光伏系统效益与发电量成正比，而决定光伏系统发电量的因素有光伏组件额定容量、现场太阳辐射量和光伏系统效率。光伏组件额定容量是在标准测试条件下得出的光伏组件输出功率峰值，由于现场条件不同于标准测试条件，光伏组件实际输出电量主要取决于现场的太阳辐射量。另外，光伏系统输出功率还应当计入各种损耗和老化降额的影响。

光伏发电受天气影响非常大，阴雨天不能发电，因此在系统设计时，要考虑当地的天气。对用电有要求的用户，还要考虑连续阴雨天的天数。

2、柴油发电成本分析

柴油发电的寿命周期成本为：柴油发电投资成本，主要有柴油发电机组及配套设施的购置费、工程费；寿命周期内的燃油费；是机组寿命周期内的运行维护成本。主要有机组寿命周期内的维修费用、机油等耗材费用。在各项费用中，燃油费所占比重较大，它决定于柴油机组在寿命周期内的总发电量，耗油率和柴油平均价格。

下面以一个30KW系统做一个对比，纯离网光伏、柴油机、油光互补等3个系统，安装地在海岛，主要负载是照明，风扇，海水淡化设备，白天用电50度，晚上用电90度，平均日照时间取4小时，连续阴雨天算2天。

30KW离网系统包括光伏组件，支架，蓄电池，逆变器，其中组件和蓄电池的成本最高，组件的寿命为25年，蓄电池的寿命为5年，逆变器的寿命15年。根据负载要求，逆变一体机选用40KVA，组件45KW，174块蓄电池2V2000AH，初期投入约75万。

油机选用东风康明斯4BT3.9G2， 初资成本为4.5万元。柴油平均价格为6000元/吨，该机组在1000小时的发电量300度，柴油消耗量5.5吨，燃油费为3.3万。如果运营维护费按燃油费的10%近似估计，加上柴油储存成本，则30kW柴油机组在1000小时寿命周期内的净成本为3.84万元。柴油发电成本为1.28元/度

油光互补系统采用光伏发电为主，以柴油机为辅助，设计蓄电池时不考虑阴雨天，逆变一体机选用40KVA，组件45KW，174块蓄电池2V500AH，30KW柴油机，初期投入45万。

由于近年来并网光伏系统及关键部件的价格持续下降，并在计及补贴的情况下，光伏发电成本已经达到与电网供电成本的经济水平，可形成经济性更好的用电系统方案。

在无电网地区，柴油发电机组与光伏系统构成混合供电系统，与柴油机组单独作相比，维护成本低，无噪声，发电成本也低。和纯离网光伏，可节省大量的昂贵的蓄电池，综合发电成本也就低下来了。

并网光伏发电经济性的分析，应当对整个生命周期内成本、补贴和效益进行详细分析，而不能只考虑初投资成本。

Photovoltaic power generation has the characteristics of high initial investment cost and low operation and maintenance cost. In the economic analysis of photovoltaic power generation, cost and benefit should refer to the total cost and total benefit within the life cycle of photovoltaic system.   Policy subsidies are an important factor that must be included in the analysis process and can offset part of the cost of grid-connected PV system construction.  

 

 

 

Life cycle cost of grid-connected PHOTOVOLTAIC power generation system = investment cost + operation and maintenance fee - subsidy, grid-connected photovoltaic system investment cost, including photovoltaic modules, batteries, inverters, power distribution cabinets, brackets, cables and other equipment and materials purchase fees, as well as engineering construction fees and transportation fees;   The operation and maintenance costs include the salaries of operators, the maintenance fees of inverters and other electrical equipment, and the cleaning fees of photovoltaic modules, etc. The operating period of photovoltaic systems is generally 20-30 years.  Total amount of policy subsidies enjoyed during the construction and operation of photovoltaic system.  Unlike coal-fired power generation, which requires energy acquisition, transportation, storage and disposal of residues, photovoltaic systems input energy from the sun, require no other energy and produce little residue during their operational life.   If the photovoltaic array is fixed, there are no fragile rotating parts in the photovoltaic system, and the service life of the components and other major electrical equipment is more than 20 years, and the maintenance workload of the system is also very small.  Therefore, the operation and maintenance cost of photovoltaic system is significantly lower than that of traditional power generation system.  

 

 

 

The efficiency of photovoltaic system is directly proportional to the power generation, and the factors that determine the power generation of photovoltaic system are rated capacity of photovoltaic modules, on-site solar radiation and photovoltaic system efficiency.   The rated capacity of pv modules is the peak output power of pv modules under standard test conditions. Since the field conditions are different from the standard test conditions, the actual output power of PV modules mainly depends on the amount of solar radiation at the site.  In addition, the output power of the photovoltaic system should be included in the influence of various losses and aging derating.  

 

 

 

Photovoltaic power generation is greatly affected by the weather, and it cannot be generated on rainy days. Therefore, local weather should be considered when designing the system.   Users who require electricity should also consider the number of consecutive rainy days.  

 

 

 

2. Cost analysis of diesel power generation  

 

 

 

The life cycle cost of diesel power generation is as follows: the investment cost of diesel power generation, mainly including the purchase cost and engineering cost of diesel generator set and supporting facilities;   Fuel costs during its life cycle;  Is the operation and maintenance cost of unit life cycle.  There are mainly maintenance costs, oil and other consumables costs in the life cycle of the unit.  Among all the costs, fuel costs account for a large proportion, which is determined by the total power generation, fuel consumption rate and average diesel price in the life cycle of the diesel unit.  

 

 

 

A 30KW system, pure off-grid photovoltaic, diesel engine, oil light complementary and other three systems, are installed in the island, the main load is lighting, fan, seawater desalination equipment, daytime power consumption of 50 degrees, night power consumption of 90 degrees, the average sunshine time is 4 hours, continuous cloudy and rainy day 2 days.  

 

 

 

The 30KW off-grid system includes photovoltaic modules, supports, batteries, and inverters. The cost of modules and batteries is the highest. The life of modules is 25 years, the life of batteries is 5 years, and the life of inverters is 15 years.   According to the load requirements, the inverter adopts 40KVA, 45KW components, 174 batteries 2V2000AH, and the initial investment is about 750,000 yuan.  

 

 

 

Dongfeng Cummins 4BT3.9G2 was selected for the oil engine, and the initial capital cost was 45,000 yuan.  The average price of diesel is 6000 yuan/ton, the generating capacity of the unit is 300 degrees in 1000 hours, the diesel consumption is 5.5 tons, and the fuel cost is 33,000 yuan.  If the operating and maintenance costs are estimated at approximately 10% of fuel costs, plus diesel storage costs, the net cost of a 30kW diesel unit over its 1000 hour life cycle is $38,400.  The cost of diesel power generation is 1.28 yuan/KWH  

 

The picture  

 

The oil-light complementary system mainly uses photovoltaic power generation, with the diesel engine as the auxiliary. The battery design does not consider rainy days. The inverter adopts 40KVA, 45KW components, 174 batteries 2V500AH, 30KW diesel engine, and the initial investment is 450,000 yuan.  

 

 

 

In recent years, the price of grid-connected photovoltaic systems and key components continues to decline, and with subsidies taken into account, the cost of photovoltaic power generation has reached an economic level with the cost of power supply to the grid, and a more economical power consumption system can be formed.  

 

 

 

In the area without power grid, diesel generator set and photovoltaic system constitute a hybrid power supply system. Compared with diesel generator set alone, the maintenance cost is low, the noise is low, and the power generation cost is also low.   And pure off-grid photovoltaic, can save a lot of expensive batteries, comprehensive power generation costs are low.  

 

 

 

The economic analysis of grid-connected photovoltaic power generation should carry out a detailed analysis of costs, subsidies and benefits in the whole life cycle, instead of only considering the initial investment cost.