1、光伏系統發電成本分析

光伏發電具有初投資成本高、運營維護成本低的特點，在光伏發電經濟性分析中，成本和效益應當指在光伏系統壽命周期內的總成本和總效益。政策性補貼是必須計入分析過程的一個重要因素，可以抵消一部分并網光伏系統建設成本。

并網光伏發電系統的壽命周期成本=投資成本＋運營維護費－補貼，并網光伏系統投資成本，包括光伏組件、蓄電池，逆變器、配電柜、支架、電纜等設備和材料購置費，還有工程建設費和交通運輸費；運營維護費包括運營人員工資、逆變器等電氣設備維修費、光伏組件清洗費等，光伏系統運營期一般為20-30年；光伏系統建設和運營期內享受的政策性補貼總額。與燃煤燃油發電需要購置、運輸、儲存能源以及處理殘余物的情況不同，光伏系統的輸入能量來自太陽，在運營期內光伏系統不需要其他能源，也幾乎不產生殘余物。如果光伏陣列采用固定式安裝，則光伏系統中沒有易損的旋轉部件，而組件等主要電氣設備使用壽命均在20年以上，系統的維護工作量也很小。因此光伏系統的運營維護成本明顯低于傳統發電系統的運營維護成本。

光伏系統效益與發電量成正比，而決定光伏系統發電量的因素有光伏組件額定容量、現場太陽輻射量和光伏系統效率。光伏組件額定容量是在標準測試條件下得出的光伏組件輸出功率峰值，由于現場條件不同于標準測試條件，光伏組件實際輸出電量主要取決于現場的太陽輻射量。另外，光伏系統輸出功率還應當計入各種損耗和老化降額的影響。

光伏發電受天氣影響非常大，陰雨天不能發電，因此在系統設計時，要考慮當地的天氣。對用電有要求的用戶，還要考慮連續陰雨天的天數。

2、柴油發電成本分析

柴油發電的壽命周期成本為：柴油發電投資成本，主要有柴油發電機組及配套設施的購置費、工程費；壽命周期內的燃油費；是機組壽命周期內的運行維護成本。主要有機組壽命周期內的維修費用、機油等耗材費用。在各項費用中，燃油費所占比重較大，它決定于柴油機組在壽命周期內的總發電量，耗油率和柴油平均價格。

下面以一個30KW系統做一個對比，純離網光伏、柴油機、油光互補等3個系統，安裝地在海島，主要負載是照明，風扇，海水淡化設備，白天用電50度，晚上用電90度，平均日照時間取4小時，連續陰雨天算2天。

30KW離網系統包括光伏組件，支架，蓄電池，逆變器，其中組件和蓄電池的成本最高，組件的壽命為25年，蓄電池的壽命為5年，逆變器的壽命15年。根據負載要求，逆變一體機選用40KVA，組件45KW，174塊蓄電池2V2000AH，初期投入約75萬。

油機選用東風康明斯4BT3.9G2， 初資成本為4.5萬元。柴油平均價格為6000元/噸，該機組在1000小時的發電量300度，柴油消耗量5.5噸，燃油費為3.3萬。如果運營維護費按燃油費的10%近似估計，加上柴油儲存成本，則30kW柴油機組在1000小時壽命周期內的凈成本為3.84萬元。柴油發電成本為1.28元/度

油光互補系統采用光伏發電為主，以柴油機為輔助，設計蓄電池時不考慮陰雨天，逆變一體機選用40KVA，組件45KW，174塊蓄電池2V500AH，30KW柴油機，初期投入45萬。

由于近年來并網光伏系統及關鍵部件的價格持續下降，并在計及補貼的情況下，光伏發電成本已經達到與電網供電成本的經濟水平，可形成經濟性更好的用電系統方案。

在無電網地區，柴油發電機組與光伏系統構成混合供電系統，與柴油機組單獨作相比，維護成本低，無噪聲，發電成本也低。和純離網光伏，可節省大量的昂貴的蓄電池，綜合發電成本也就低下來了。

并網光伏發電經濟性的分析，應當對整個生命周期內成本、補貼和效益進行詳細分析，而不能只考慮初投資成本。

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.