solar power optimizer 600w 800w 20A

How Solar power optimizers can recoup 90% of lost generation capacity

The output of a single PV module is often insufficient to provide the actual power demand, so it must be connected in series-parallel to form an array of PV modules to meet the design requirements. When selecting PV modules to form an array, it is common to encounter a situation where the output power after series parallel connection is less than the sum of the output power of individual modules due to inconsistent electrical parameters of each module in series parallel connection or when partial or intermittent shading or aging of the string occurs, which is called “mismatch loss” in professional terms. With the increase of PV plant operation, it will affect the actual power generation of the whole plant to different degrees.

1. Background

The traditional centralized PV power generation system will cause unestimable power loss to the PV module array due to unforeseen factors such as surrounding buildings, cloud locations, and the size of neighboring obstacles. Therefore, in recent years, domestic and foreign scholars have conducted a variety of global maximum power point research explorations for the above-mentioned PV array power multi-peak problem generated by local shading has achieved some remarkable results, but still cannot make each PV module work at its respective maximum power point (Maximum Power Point MPP), without completely solving the overall power of the string brought about by the local shadow shading problem The loss of overall string power due to local shading problem is not completely solved.

For centralized PV power generation system, because there is only one energy conversion link DC-AC, the control should consider both tracking the maximum power point of PV panels and ensuring the amplitude phase and sinusoidality of the grid output voltage, the control is more complex inverter multiple inputs using the same MPPT, which cannot identify the differences of series-parallel branch PV modules, which will significantly reduce the power generation efficiency, so for the PV module parameters Discrete or differences in solar radiation conditions caused by the energy loss is powerless.

At the same time, in the series connection if the current does not match, will cause the array work in a certain state, the array of individual photovoltaic modules in reverse bias to form a hot spot. A voltage mismatch in parallel connection can result in the formation of circulating hot spots and circulating currents within the array when the array is operating in a certain state, which can cause individual modules in the series-parallel connection to be in a power hungry state and can damage module life. The mismatch loss is even greater when the PV module array cannot operate under uniform illumination.

One of the current solutions to eliminate the effects of mismatch on the module side is the use of a solar smart power optimizer. In a module containing multiple series-connected parallel cells, each PV module is connected to a power optimizer with independent maximum power point tracking, and the output of each PV module is connected to the input of the power optimizer module.

The PV optimizer converts low current to high current as required by the series circuit and finally connects the output of each power optimizer in series and connects to a sink or inverter. The optimizer monitors and optimizes the electrical power of each PV panel. Even if any panel in the array has a mismatch problem, the other panels can still output the maximum power, thus compensating for the power loss due to the mismatch problem. With maximum energy harvesting conversion, data acquisition and communication functions, it can be quickly and easily installed in solar PV systems and can be suitable for applications in grid-connected PV systems of different sizes.

2.The basic principle of PV power optimizer

For the traditional string design scheme, when one of the components of a group of strings is shaded, such as the working current drop from the original 8A reduced to 7.5A, due to the series circuit, resulting in the reduction of the current of the whole string, then the power output of the whole string is reduced from the original 2400W to 240Wp*(1-9%)*10=2184W, reducing the proportion of 9%.

When the optimizer is added, the shaded module no longer affects the power generation of other modules, and the output current of the module is changed by the small transformer DC-DC control circuit inside the optimizer. The current of the module will be matched with the current of other modules (the optimizer needs to monitor the output current of other modules on the same string and adjust the output current of itself only after finding inconsistency). , that is, the actual loss of power 0.9%.

Each PV module is connected to the power optimizer, and each module is an independent whole with respect to the PV array. Its output power is not affected by any other modules, keeping the output at the maximum power value for the current environmental conditions. Of course the module-level optimizer can also be set to match the inverter in real time and communicate to distribute the optimal power point voltage according to the inverter. In this way the output of the optimizer connected to each module is influenced by the inverter, and is output according to the inverter’s command while ensuring that the current is consistent, so that it always works at the most efficient voltage point.

For data acquisition and monitoring, for each PV module connected to the PV optimizer, real-time voltage, current, power and DC power are transmitted to the monitoring server via the data collector, refer to Figure 1.

Figure 1

3. Power optimizer software simulation

The power generation boost of the power optimizer has a lot to do with the actual situation of the power plant. For example, the boost ratio is different between a large power plant on flat ground with no obstructions and a distributed PV plant. The boost ratio of power optimizer installation is also different between a newly commissioned PV plant and a plant with a certain number of years of grid-connected operation. Therefore it is necessary to conduct experiments through actual scenarios and accumulate data for string analysis, which can provide useful references for the optimal operation of the power plant.

The following section uses PVsyst software to initially simulate the power generation improvement of the system after using the Sunpv Solar Optimizer. System configuration reference table 1: 24 PV modules, 5.4kW capacity, using Sunpv Solar Optimizer matching string inverter, project site reference Nanjing. System architecture reference Figure 2.

Component Selection Number of components Capacity String Inverter Power Optimizer
Yingli YL260P-29b 24PCS 5.4kW 6kW-SE6000-SolarEdge Sunpv-460W
Project Location Component Azimuth Component Tilt Number of groups in series and parallel Number of components in series
Nanjing (MN7.1 weather data) 30° 2 11 pieces in a string

Table 1 System configuration

Figure 2

By modeling and arranging the components for this household system, the shading shading factors shown in Table 2 can be obtained.

-80° -60° -40° -20° 20° 40° 60° 80°  
90° 0 0 0 0 0 0 0 0 0
80° 0 0 0 0 0 0 0 0 0
70° 0 0 0 0 0 0 0 0 0
60° 0 0 0 0 0 0 0 0 0
50° 0 0 0.042 0.042 0.042 0.084 0.084 0 0
40° 0 0.042 0.084 0.084 0.084 0.084 0.084 0.042 0
30° 0 0.084 0.084 0.127 0.127 0.084 0.084 0.084 0
20° 0 0.084 0.127 0.127 0.127 0.127 0.084 0.084 0
10° 0.084 0.084 0.211 0.169 0.169 0.211 0.127 0.127 0.084
0.084 0.253 0.253 0.295 0.211 0.295 0.422 0.249 0.245

Table 2 Shading shading factor

Figure 3 shows the simulation results, from which it can be seen that the electrical performance mismatch loss between components of the same string is reduced to 0 after using the optimizer.

Figure 3: PVsyst simulation results

Figure 4 shows the annual PV output gain after adding the optimizer, and the percentage of improvement is different under different irradiation. Although the accuracy of the simulation of the power optimizer system is still lacking in PVsyst 6.0, the power output is improved in general from the software simulation.

Figure 4: Inverter DC-side input power gain (unit: W)

4. Summary

Regardless of whether the PV array is a centralized MPPT architecture or a string MPPT architecture, inconsistencies in the characteristics of the PV modules in the array can easily cause current mismatch problems, resulting in a significant decrease in the overall power generation efficiency of the system. To solve this problem, the industry has proposed a distributed PV power optimizer array architecture, which provides a new way to solve the current mismatch problem of series-connected modules of PV arrays.

In this paper, based on the string MPPT architecture, a power optimizer is connected to individual PV modules and the power generation gains of PV strings before and after using the optimizer are analyzed. When there is mismatch in the PV array, the PV experimental array with the power optimizer installed can improve the power generation and the power generation gain varies depending on the mismatch ratio.

According to the data of our previous relevant experiments, the PV power station that has been running for about two years, the 5° slope angle of the color steel tile roofing components arranged in a downhill way to enhance the proportion of about 10% or more, after the actual data measurement, according to the current market price of the optimizer system (including remote monitoring system), then the cost recovery period should be about 7-8 years.

Click to solar power optimizers

Click to solar power optimizers

Foshan Sunpv Technology Co., Ltd. specializes in the manufacture of solar micro inverters, solar power optimizers and rapid shutdown. Our factory has over 10 years of experience in manufacturing precision electrical products. Our high quality solar related products are sold well in many countries around the world. We have certifications from various countries and are committed to providing our customers with the highest quality products and services! We warmly welcome new energy companies from all over the world to establish long-term cooperation with us!

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