Five Elements of PV Revenue: 1MW Distributed PV Investment Budget

The country has recently issued a series of policies and measures to support the development of China's photovoltaic market. Its installed target in 2014 has also been adjusted to 14 GW. The current policy has a low rate of return. It is a challenge to all PV developers to develop photovoltaic projects and achieve profitability under the existing policy framework. How to develop distributed photovoltaics at a low electricity price and realize profitability.

2014 is surely the year for the development of China's photovoltaic market, and it is also the year for testing the survivability of photovoltaic developers. The author believes that as long as firmly grasp the five elements of photovoltaic projects: policy, quality, safety, cost and energy efficiency, they can be invincible. The risks and countermeasures for enjoying and implementing policies and investment and financing have been widely discussed. This article focuses on how to effectively control the photovoltaic power generation system from the four aspects of quality, safety, cost, and energy efficiency, so as to maximize the benefits of the photovoltaic power generation system. It is reported that related training has also started, and photovoltaic companies should pay attention.

From 2014 onwards, the state will implement different online benchmark prices for the large-scale PV power plants in the sub-resources area. The national unified benchmark electricity price for the Internet will be adjusted to RMB 0.9/kWh (Type I area) and RMB 0.95/ton respectively. kWh (Type II area) and 1.0 Yuan/kWh (Type III area), at the same time, the incentive for distributed photovoltaic power generation is changed from initial investment subsidies to electricity subsidies (0.42 Yuan/kWh), which further requires that photovoltaic systems not only With low costs, we must also focus on quality and power generation efficiency to maximize the benefits of photovoltaic power generation systems. In order to achieve this goal, the following five points are very important: 1) to study and use existing national policies to avoid construction, networking, operation and other operational level risks; 2) strictly control the quality of photovoltaic system components and engineering; 3) pay attention to the photovoltaic system Safety, to avoid catastrophic accidents; 4) To reduce the construction costs, operating costs, and power generation costs of photovoltaic systems under the premise of ensuring quality; 5) Improve the PV system performance index (PR) through refined design.

Strictly control the quality of photovoltaic system

The quality of photovoltaic systems depends mainly on the quality of components and the quality of construction projects. The basis for judging the quality of components and quality of construction projects is whether they meet or meet the requirements of relevant technical standards. Currently released technical standards relating to photovoltaic systems and components include photovoltaic modules, balancing components (inverters, controllers, batteries, etc.), stand-alone photovoltaic systems, grid-connected photovoltaic systems, large-scale photovoltaic power plants, building photovoltaics, solar trackers , Photovoltaic pumps, etc. With technical standards or a product that has passed third-party testing, it does not mean that all products meet the quality requirements. In order to ensure that all of the model's products meet the quality requirements of the standard, the entire production process of the product and the manufacturer's production management must also be certified.

Photovoltaic modules, inverters, and batteries are not general consumer products and their service life is as long as several years or even decades. However, their long-term reliability cannot be judged from appearance and real-time detection. In order to ensure the quality and long-term reliability of photovoltaic products and components, developers can adopt the following measures: 1) The most basic is to require manufacturers to provide authoritative inspection and certification reports, so as to ensure that the technical performance of the submitted products meets the requirements of the technology. The standard has passed the third-party inspection, and the mass-produced products are produced according to the same standards as the submitted products; 2) In order to ensure the long-term reliability of the photovoltaic components and the long-term stability of the quality, the manufacturer may be required to provide product quality insurance. A trend to reduce the risk of developers (At present, some insurance companies, such as Indotek, have introduced 25-year power guarantees for export PV modules); 3) If the product can not provide quality insurance, they can hire experienced third parties Implementation of product supervision, and prior to product delivery, sampling inspection of the batch of products; 4) In view of photovoltaic components and inverters are not short-term consumer goods, after a year of on-site operation requires re-sampling, "infancy" failure rate Should be within the scope of the contract.

In addition to product and component quality, the design and construction of photovoltaic projects is also very important. In order to ensure project quality, project developers can also entrust qualified and experienced third parties to review and supervise the entire process of engineering design, construction and installation, and project acceptance. At present, there are already such services in the country, and the service fees charged are quite low. We believe that such services can play a key role in ensuring the quality of the photovoltaic system. It is a value-added service for developers. In addition to the acceptance of the PV project, the PV project also needs to be post-assessed after the PV system is operated for one year. The assessment index of the power plant should be based on the “Performance Index” (PR).

Guarantee the safety of photovoltaic systems

Safety is the most important part of the quality of a photovoltaic system. The safety of photovoltaic systems includes: construction safety, power grid safety, protection against electric shock, system wind resistance, lightning protection, fire and arc protection, anti-theft, and sand storm prevention. Construction safety includes construction load, leakage prevention, insulation layer insulation and building fire protection. Building safety assessment needs professional departments. Distributed photovoltaic combined with buildings should first pass construction safety assessment before construction. Breaking of the pole insulation will cause a parallel circuit arc, and the destruction of the ground insulation will produce an arc to the ground. Therefore, if the quality of cables, connecting devices, contactors, circuit breakers is incorrect or the installation is not serious, arcing may occur. Causes fire.

At present, there is no internationally uniform arc detection standard, nor can conventional electric current and voltage detection be used to determine whether an electric arc has occurred. When an electric arc occurs, it will generate arc light and radiation. Research methods at home and abroad are being studied based on this feature. In order to avoid the occurrence of series-arc arcs, the most important is the installation quality. Each connection point must be firmly connected.

The wind resistance of the system needs to be designed according to the local maximum wind speed in 30 years, but it needs to be optimized and balanced among various factors such as the installation angle of the array, annual power generation, construction load, land occupation, and shading of shadows, such as the array angle and wind The load is directly related. In order to maximize the annual power generation and design the square inclination, it may be necessary to withstand greater wind loads, thus requiring a larger counterweight, and such a counterweight exceeds the maximum load the building can withstand. This requires changing the inclination of the policy to accommodate the construction load; for example, high dip angles require more land, and the land occupation increases the cost, sometimes the roof area is limited, and there is no room for greater spacing between the phalanx. The square wind resistance design needs to be adapted to local conditions.

Reasonably reduce the cost of photovoltaic power generation

The cost of the PV system directly affects the final revenue. The cost includes the construction cost, the operation and maintenance cost and the final generation cost. At present, the reasonable construction cost of photovoltaic system is about 9 yuan/Wp. Although large-scale photovoltaic power plants have scale effects, the cost of civil engineering projects and boost stations in stations is relatively high; while the scale of distributed photovoltaics is small, the cost of equipment is relatively low. Higher, but the cost of civil construction and network access systems is relatively low, so the initial investment in large-scale photovoltaic power plants and building photovoltaics is virtually the same.

The typical estimates for 10MW large-scale photovoltaic power plants and 1MW distributed building photovoltaics are as follows:

It can be seen from the estimated breakdown ratio that photovoltaic modules account for approximately 49% of the total investment, inverters and other electrical equipment accounts for approximately 10%, and cables and brackets each account for approximately 10%. Higher, there is a certain price reduction space, photovoltaic construction investment may be 8 yuan / Wp. According to the normal design, the current investment in photovoltaic system construction is almost impossible to fall below 8 yuan/Wp, but for some special applications, there is room for price reduction. For example, for 3-5 kW household grid-connected photovoltaics, generally 10-20 PV modules are required. If direct grid-connected AC PV modules (ACModule, or micro-inverters) are used, there is no longer a need for a combined box, AC or DC. Power distribution and separate inverters also eliminate the need for DC cables, and installation work has also become very simple, so construction investment can be reduced to 7 yuan/Wp.

Photovoltaic power generation belongs to solid-state power generation. No matter when it is a photovoltaic module or an inverter, it is static, there are no rotating parts, and no supplementary fuel is needed. If the quality of the components passes, maintenance is very simple and can be done unattended. For a large-scale photovoltaic power station, the annual operation and maintenance costs are generally about 1%, and for distributed building photovoltaics, it is generally not more than 2%. Many photovoltaic systems in foreign countries are unattended operation, and the cleanliness of photovoltaic arrays mainly depends on wind and rain. China's atmospheric conditions and environment are different from those of foreign countries. Whether it is the western desert or the eastern city, it cannot rely on wind and rain to clean itself. It has been reported that the shading loss of dust and stains is based on a severity of about 2%-10%, and even more than 20%. Clean 10MW photovoltaic power station, as long as it can increase the power generation by 2%, it can send about 300,000 kWh, and the net income is about 300,000 yuan.

In order to reduce the cost of power generation (yuan/kWh) at the same location where the resource conditions are the same, the most effective method is to use a solar tracker so as to greatly increase the power generation without significantly increasing the construction cost and achieve the purpose of reducing the cost of power generation. According to test data from 23183 Meteorological Station 1961-1990 (30 years) in Phoenix, Arizona, the amount of radiation received by the solar tracker is much larger than that of a fixed plane: the radiation data is measured by the weather station from 1961-1990. The amount of radiation obtained includes the comparison of the amount of solar radiation collected by various flat collectors under different operating modes.

From the local conditions and measured radiation data, the gain of the radiation amount of the east-west tracking on the horizontal axis is increased by 23.1% compared with the installation of the fixed-pitch latitude angle, and the tilt single-axis tracking of the tilt angle of the main shaft can be increased to 32.3%. Compared with the fixed inclination angle, the tracking system has a radiation gain of 36.9%. It is an indisputable fact that the solar tracker can effectively increase the amount of power generated and reduce the cost of power generation. However, why can it not be used more widely? The increased cost of automatic tracking is not a problem. The price of most inclined single-axis trackers is At around 1.5 yuan/Wp, or even lower, it is about 0.5-0.7 yuan/Wp higher than that of the fixed bracket, which is an increase of up to two years to recover the increased cost compared to the annual increase of more than 20% in power generation. The main problem is reliability. As long as the reliability problem is solved, the solar tracker will undoubtedly be widely promoted.

Improve PV system performance index

Internationally, the performance index of photovoltaic systems has been studied for many years. From the data, the average PR of PV systems in early years was only 65%. In recent years, the average of PR has increased to 74%, but few systems have reached 80%. the above.

There is currently no "China efficiency." Beijing Jian Heng Certification Center and other units are researching and formulating China's “China Efficiency” that is in line with the actual working conditions according to China’s lighting conditions.

IEC 61724 (Photovoltaic system performance monitoring-measurement, data exchange, and analysis guidelines) proposes a parameter-performance index (PR) for evaluating the performance of photovoltaic power generation systems. It should be noted that: 1) The photovoltaic system performance index (PR) has eliminated the difference in solar energy resources and truly reflects the quality and efficiency of the photovoltaic system. For example, in a photovoltaic power plant in Tibet, the annual equivalent utilization hours are as high as 1600 hours. The peak hours of sunshine on the phalanx is 2000 hours, and the PR of the system is equal to 80%. The Beijing PV system is full of 1200 hours. The radiation of the square is 1400kWh/m2, and PR=86%. The photovoltaic system of Beijing Although the total number of hours of electricity generation is not as good as that of Tibet, quality and energy efficiency are obviously higher than those of Tibet. 2) Although the automatic sun tracker can increase power generation and reduce the cost of power generation, it does not increase PR because the denominator's radiation is also increased. 3) The PR value does not exclude temperature differences. Different use locations or different installation methods will affect the operating temperature of the photovoltaic cell. In the tropical regions and photovoltaic systems working in cold regions, even if the quality is the same, the PR of the photovoltaic system in the tropics The value will also be low. In order to objectively compare the performance of the power station, temperature correction is also required. There are many factors affecting PR, including: electrical efficiency of the system (series and parallel loss of components, inverter efficiency, transformer efficiency, other equipment efficiency, temperature rise loss, line loss, etc.), component degradation, occlusion, light reflection loss, MPPT errors, fault conditions, and levels of operation and maintenance do not consider the effects of measurement errors and grid abandonment.

California efficiency (CEC efficiency): California's efficiency not only considers California's lighting conditions, but also considers the temperature of photovoltaic cells. The influence of the photovoltaic cell temperature is mainly reflected in the input voltage of the photovoltaic array of the inverter. When the temperature is high, the input voltage is low, and when the temperature is low, the input voltage is high. The test conditions for CEC efficiency are as follows: In the three conditions of "rated input DC voltage", "maximum input DC voltage" and "minimum input DC voltage", respectively, record their 10%, 20% of the maximum input power, 30%, 50%, 75%, and 100% of the 18 conversion efficiency under the six conditions. Which conversion efficiency = output power / input power X100%. California efficiency has "maximum efficiency", "average efficiency" and "weighted efficiency". The weighted efficiency does not consider the temperature effect. It only considers lighting conditions and can be compared with "European efficiency". The highest efficiency is the highest mark of conventional inverters. Efficiency; the average efficiency is the consideration of the lighting conditions and the influence of the ambient temperature.

The three California efficiencies are defined as follows: Peak Efficiency: Refers to the highest of the above 18 conversion efficiency; Nominal Average Efficiency: refers to the input of 50%, 75%, and 100% of the three input DCs. The average of 9 conversion efficiencies recorded under power;

CEC Weighted Efficiency: Consider changes in lighting conditions throughout the day. According to the DC input maximum power of 10%, 20%, 30%, 50%, 75% and 100% under six conditions, the weight values ​​are 4%, 5%, 12%, 21%, 53% and 5% respectively. The assigned weighted efficiency value is assigned.

If the photovoltaic components or the quality of the project is poorly controlled, the troubleshooting losses will increase significantly, even exceeding 10%. Therefore, strict quality control is an important prerequisite for reducing troubleshooting losses. The phenomenon of abandoned light (including delayed access and limited emission) has now appeared in large-scale photovoltaic power plants in the western region. With the synchronization of photovoltaic and grid planning and construction, this problem will be solved.

In order to obtain the performance index (PR) of the photovoltaic system and thus accurately assess the quality and energy efficiency of the photovoltaic power plant or distributed photovoltaics, a high-quality data monitoring and data acquisition system is necessary. The data used in this paper, including the gain of the solar tracker, the temperature loss of different installation methods of the photovoltaic system, and the PR value of the photovoltaic power station, all adopt foreign data. The reason why it is so forced is that it is difficult to find complete domestic data.

Therefore, data collection and monitoring are very important for plant evaluation and technological improvement, and also represent the maturity of photovoltaic power plant construction. The data, sampling accuracy, sampling period and monitoring period monitored and collected by the data acquisition and monitoring system installed in the photovoltaic project shall comply with GB/T 20513 (IEC 61724) “Guidelines for monitoring, measurement, data exchange and analysis of photovoltaic systems”. The request.

Biochemical Filter

Biochemical filter is the core spectral component in the optical path system of biochemical analyzer, and its optical performance directly affects the accuracy and sensitivity of equipment inspection. The biochemical filter produced by our company has the characteristics of high signal-to-noise ratio, large transition zone change rate, high transmittance, deep cutoff degree and so on.

Biochemical Filter,Laser Detector Filter Cartridge,Filter Laser Cutting Machine,Biochemical Bio Filter

Changchun Champion Optics Co.,Ltd , https://www.champion-optics.com