The daily output power of a solar cell module is related to the number of cells in series in the solar cell module. The voltage of the solar cell under sunlight will decrease with the increase of temperature, which will lead to the increase of the voltage of the solar cell module with the temperature. and decrease. Based on this physical phenomenon, solar cell module manufacturers have designed different modules according to the different climatic conditions in which the solar cell modules work: 36 tandem modules and 33 tandem modules.
The 36-piece solar cell module is mainly suitable for high temperature environment applications, and the 36-piece solar cell module can work near the Imp even in a high temperature environment. Usually, the system voltage of the battery used is 12V, and 36 pieces in series means that under standard conditions (25℃), the Vmp of the solar cell module is 17V, which is much higher than the 12V voltage required for battery charging. When these solar cell modules work at high temperature, since the loss voltage of high temperature solar cell modules is about 2V, so Vmp is 15V, which can charge various types of 12V batteries even in the hottest climate conditions. Using 36 solar cell modules in series is best used in hot areas, and can also be used in systems with peak power tracking equipment installed, which can maximize the potential of solar cell modules.(Peak power of solar modules)
33 solar cell modules connected in series are suitable for use in mild climate environments. Under standard conditions (25℃), the Vmp of solar cell modules of 33 solar cell modules is 16V, which is higher than the 12V voltage required for battery charging. When these solar cell modules work at 40~45℃, the solar cell module loses voltage of about 1V due to high temperature, so Vmp is 15V, which can also charge various types of 12V batteries. But if operating in very hot climates, the solar module voltage drops even more. If it reaches 50°C or higher, the voltage will drop to 14V or less, and the current output will drop. This is not harmful to solar cell modules, but the current generated is not ideal, so 33 solar cell modules in series are best used in mild climate conditions.
Because the output power of the solar cell module is calibrated in the standard state, but in actual use, the sunlight conditions and the environmental conditions of the solar cell module cannot be exactly the same as the standard state. Therefore, it is necessary to find a method that can use the rated output power of the solar cell module and meteorological data to estimate the output power of the solar cell module under actual conditions, and can use the peak hours method to estimate the daily output of the solar cell module. The method is to convert the solar radiation on the inclined plane of the actual solar cell into the equivalent hours using standard solar radiation (1000W/m2 irradiation). Multiplying this number of hours by the peak output of the solar module gives an estimate of the amp-hours the solar module outputs per day.
To calculate the Ampere Hours output by a solar module per day, the peak hours can be multiplied by the solar module’s Imp. There are some disadvantages in using the peak hour method, because some simplifications are made in the peak hour method, which leads to a certain deviation between the estimated results and the actual situation. First, the temperature effect of the solar cell module output is ignored in this method. The Imp of the solar cell module needs to be compensated in the calculation. Because when working, the voltage across the battery is usually lower than Vmp, so the output current of the solar cell module will be higher than Imp, and using Imp as the output of the solar cell module will be conservative. In this way, the temperature effect has a greater impact on the output of the solar cell module composed of fewer cells connected in series than the output of the solar cell module composed of more cells connected in series.
Therefore, the peak hour method is more accurate for 36 solar cell modules connected in series, but poorer for 33 solar cell modules connected in series, especially in a high temperature environment. For all solar modules, predictions are more accurate in cold climate regions. Second, in the peak hour method, the total solar radiation measured in meteorological data is used to convert it into peak hours. In fact, in the early morning and dusk of each day, there is a period of time when the radiation is very low, and the voltage generated by the solar cell module is too low to supply the load or charge the battery, which will lead to an overestimation.
The assumption that solar module output is estimated using the peak hour method is that the solar module output is completely linear in relation to illumination, and that all solar modules convert solar radiation into electricity equally. But that’s not the case, and this method of multiplying peak hours by peak current can sometimes overestimate the output of some solar modules. In general, however, the peak hour estimation method is a very efficient method for quickly estimating the output of a solar cell module given the known solar radiation data on the local solar cell slope.
In the design, the two parameters of the solar module working voltage and solar module power are mainly determined. At the same time, according to the current requirements of solar cell materials, process level and lifespan, the area of the selected solar modules should be more suitable, and the connection between the single solar cells should be reliable and the combined loss should be small.