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100-102 Determine solar module power and matrix setting

Author: Source: Datetime: 2017-01-16 11:52:57

4.3.1.4 Determine solar module power and matrix setting


The following describes the design of the matrix current, voltage and output power. The steps of the design calculation are as follows,
(1) calculate the average daily total radiation
 The calendar year on average monthly solar radiation and the basic data on behalf of people U-1), you can calculate the tilt square on the level
Day total radiation, the unit into Mw.h / cm2 divided by the standard daylight intensity to obtain the average peak sunshine hours Tm "
Tm = ItmW • h / cm2 / (100mW / cm2)
(2) to determine the square matrix of the best current output should be the minimum current Imin = Q / (Tm • θ1 • θ2 • θ3), Where Q - total daily power consumption of the load, A h;
Θ1 - battery charging efficiency;
Θ2 - square array surface due to dust pollution or aging caused by the correction factor, usually 0.9 ~ 0.95;
Θ3 - the correction factor for the loss of the square matrix combination and the deviation from the maximum power point, usually 0.9 to 0.95.
From the minimum total solar radiation in each month, the minimum peak sunshine hours Tmin in each month can be calculated. The maximum current that the square should output is Imax = Q / (Tmin • θ1 • θ2 • θ3)
The optimum square current is between Imin and Imax, and the specific value can be determined by the trial method. First select a current value I, the method is to calculate the monthly output of the output power of the square, the battery state of the year to test the charge, the square output power output formula: Q + = LNIt • θ1 • θ2 • θ3 / (100 mW / cm2) (4-7)
Where N is the number of days in the current month. The monthly load power consumption is: Qmonth = NQ (4-8)
If ΔQ is negative, if the ΔQ is negative, it means that the power output of the phalanx array is less than the power consumption. If ΔQ = Q + Q, , To use the battery to store the energy to add, the battery is in a loss state.
If the battery state of charge throughout the year than the original discharge depth (usually ≤ 0.5), should increase the square output current; if the charge state is always much higher than the depth of discharge allowable value, you can reduce the square current. Of course, can also increase or decrease the battery capacity. If necessary, you can also change the value of the square angle to obtain the best square current Im
(3) determine the square array voltage
The output voltage of the phalanx should be large enough to ensure that the battery can be charged efficiently throughout the year. Therefore, the square matrix of the operating voltage in any season must be met
V = Vf + Vd + vt (4-9)
Where vf - battery float voltage;
Vd - voltage drop due to blocking diode and line DC losses;
 Vt - temperature drop caused by the pressure drop.
The maximum nominal operating voltage, operating current and output power (peak tiles) of the solar module sold by the manufacturer are in the standard state (air mass AM = 1.5, temperature 25 ° C, solar radiation 100 mW / Cm2). From the solar cell's temperature characteristic curve, when the temperature rises, its working voltage has decreased significantly, with the following formula to calculate the pressure drop vt
Vt = a (Tmax - 25) Vm (4-10)
Where a - the temperature coefficient of solar cells (crystalline silicon cell a = 0.005, amorphous cell a = 0.003);
Tmax - the maximum operating temperature of solar cells;
Vm - the nominal operating voltage of the solar cell.
(4) to determine the square array power (solar panel capacity)
F = optimum operating current (I) x operating voltage (V) (4-11)
In this way, according to the calculated battery capacity, the square of the solar cell current, voltage and power, with reference to manufacturers
Batteries and solar modules performance parameters, you can select the appropriate model and specifications. The number of components in series and in parallel is also easily determined.

In the purchase of solar cell components, if it is used in a certain way series, in parallel form a square, the designer and the user is best to advance to the manufacturer: the characteristics of each component curve must have good consistency , So as to avoid the combination of the efficiency of the matrix is too low, the general should be required on the combination of more than 97% efficiency.


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