Little is known about the system efficiency of power plants in the industry. Many people believe that the efficiency of photovoltaic power plants are designed with 75%-80% efficiency, then the operation process should be run according to this efficiency. So many users of the power plant system efficiency issued a lot of probing: how can today’s efficiency as high as 95%? How come yesterday’s efficiency was only 55%? How can the efficiency of this month be only 65%? This is different from the traditional concept, is there something wrong with my power plant? Is there something wrong with TAOKE’s monitoring system?
In fact, there is no need to be surprised, because the system efficiency of photovoltaic power plant is constantly changing with the intensity of irradiation, the lower the irradiation efficiency is also lower, when the irradiation reaches 1000w/m2, the efficiency loss is only less than 5% (of course, this is in the season when the temperature is not very high); what is the reason for this? The main points are as follows.
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One, the losses of modules, inverters, cables, etc. do not vary linearly as we think.
Secondly, when the radiation is very low (cloudy or rainy), there is a stage where the string voltage is too low and the inverter cannot start; (and the irradiation is cumulative)
Third, the inverter has a certain self-consumption situation (self-consumption varies very little with the load), which accounts for a high proportion of power generation under low irradiation conditions, resulting in a lower system efficiency.
How to calculate the peak sunshine hours? Algorithm for system efficiency (X)?
Peak insolation hours: It is a parameter that converts instantaneous irradiation values into hours after accumulation, and is used to evaluate theoretical power generation and irradiation intensity over a period of time; with this value it is easy to measure the system efficiency, the accuracy of which depends on the sampling accuracy of the weather station and its algorithm. Some companies also refer to this as total irradiation.
System efficiency algorithm (X): Power generation (kWh) ÷ Installed capacity (kW) ÷ Peak sunshine hours (h) ÷ 100 = X%
What are the steps and methods to improve efficiency throughout the life cycle of a power plant?
First, the optimal design of the power plant throughout its life cycle should be fully considered, and the O&M team should intervene at the design stage in order to consider in advance the convenience and economy of later O&M.
Second, third-party testing agencies and construction supervision companies should be introduced to strictly control the quality of power plant equipment and construction quality, especially the long-term reliability of the system under harsh outdoor environmental conditions.
Third, regionalized operation and maintenance centers should be established to reduce the cost of single project operation and maintenance of distributed power plants.
Fourth, actively explore the critical point of power plant component cleaning in different regions to maximize the comprehensive benefits of power generation – cleaning.
Fifth, the actual problems exposed during the operation and maintenance process should be fed back to the design as soon as possible, so that it can continuously optimize the follow-up program.
