Do you know how many forms of PV mounting structures? Here is the answer. Let's have a look.
 
There are roughly five operating modes of photovoltaic power stations (rooftop photovoltaic systems, ground photovoltaic systems and floating photovoltaic systems) as follows.
 
1. The best angle fixed (currently the most widely used)
2. Flat single-axis tracking type
3. Oblique uniaxial tracking type
4. Biaxial tracking type
5. Fixed adjustable type

The most fundamental difference of different operation modes lies in their power generation differences. Of course, there will be differences in initial investment, operating and maintenance costs.
 
The forms of photovoltaic mounting structures
 
At different latitudes, the increase rate of power generation in various operating modes is obviously different. There are roughly the following types.
 
1. The best angle fixed type
At low latitudes, due to the small optimal inclination angle, the generation increase is very little ( For example, when the latitude is at 8°, it is almost constant.). At high latitudes, the optimal inclination angle is large and the power generation increases significantly ( For instance, when the latitude is at 50°, the increase is about 25%.).
 
2. Flat single-axis tracking type
This operation tracks changes in the sun's incidence angle over the course of a day, and the increase in power generation is significantly greater at low latitudes than high latitudes. It is generally believed that this operation is more suitable for use in areas with latitude below 30°. It can increase power generation by 20-30% compared to the type one. Of course, at high latitudes, the increase over type one is nearly 20%.
 
3. Oblique uniaxial tracking type
This mode of operation is obviously a combination of "type one" and "type two" advantages. Just as "type one" does not work well at lower latitudes, it does not perform much better than "type two" at lower latitudes. Therefore, it is more suitable for high latitudes.
 
In this way, the forces on the mounting structures (mountings, rotating shafts) on both sides of the array must be different. Due to the large optimal dip angle in high-latitude areas, if the "optimal dip angle oblique uniaxial" is adopted, the unbalanced forces on both sides will be very large. Therefore, a smaller angle is generally used in engineering.

4. Biaxial tracking type
By tracking changes in the sun's incidence angle over the course of a day and a year, this type produces the greatest increase in power generation.
 
5. Fixed adjustable type
This operation mode is to adjust the bracket angle according to the change of the sun's incidence angle within a year, so as to achieve the improvement of power generation.
 
Then, how do these different operations increase power generation? Compared with horizontal radiation, fixed power generation is increased in spring, autumn and winter at the expense of power generation in summer. The single-axis tracking is almost completely parallel, and the bi-axis tracking is opposite to the single-axis tracking, which improves the power generation in spring, autumn and winter. The tracking type (single axis, double axis) is relative to the fixed type, which improves the power generation in the morning and evening.
 
In theory, the tracking mounting structure is always better than the fixed one in generating electricity. Therefore, why do we still prefer the way of the fixed type?
 
First, it is about the initial investment, land occupation, operation and maintenance costs.
Both the investment of PV mounting systems, the footprint of the same installed capacity and the operation and maintenance costs follow the rules.
 
The biaxial tracking type > the inclined uniaxial tracking type > the flat uniaxial tracking type > the fixed adjustable type > the optimal angle fixed type
 
Second, failure rate and tracking accuracy

High failure rate is a common feedback problem for the tracking mounting structure. The existing photovoltaic power stations in China are mainly located in the northwest, where the wind and sand are heavy. The damage to the tracking axis is particularly large. In the event of a failure, even the basic amount of electricity produced cannot be guaranteed, let alone increased. Many power station staff have expressed that the tracking mounting structure is easy to break. In addition to the failure rate, the tracking accuracy can not reach the ideal value, especially the biaxial tracking. As a result, electricity production will rise less than originally expected.

In conclusion, in general, the photovoltaic power station capacity gain with the tracking mounting structure is obvious, but it covers an area of big and the mounting structure cost, operation and maintenance cost is high. In different latitude areas, the tracking mounting structure for capacity gain effect also exists certain differences. Due to the above factors, fixed mounting structure and tracking have no decisive in the present stage. The cost performance of tracking mounting structure may not be high. Therefore, in actual situations, it is necessary to analyze and compare specific projects to select the best mounting structure.
 
Photovoltaic power stations at different latitudes adopt different forms of PV mounting systems to cover different areas. The latitude and angle of PV mounting systems have the greatest influence on the area of photovoltaic power station. For photovoltaic power stations with the same latitude, the fixed inclination mounting structure occupies the smallest area, followed by the flat uniaxial tracking mounting structure. The inclined uniaxial tracking mounting structure occupies the largest area. The larger the inclination angle, the larger the area.
 
The amount of solar radiation received by different mounting systems is different. The tracking mounting structures can track the direction of incident sunlight, which can increase the gain of solar radiation received by the components. Thus, the power generation increases. Although the amount of solar radiation determines the generating capacity of a photovoltaic power station, the ratio of solar radiation to the gain of the generating capacity of the power station is not completely consistent due to the influence of array shielding, line loss and temperature.
 
Therefore, although the tracking mounting structure can greatly improve the power generation of photovoltaic power stations and the investment income ratio of photovoltaic power stations. It has a good application prospect. However, considering the cost increase, stability, reliability and operation and maintenance cost of the tracking mounting structure, the tracking mounting structure has not been widely applied at present.