1. Conversion efficiency
N=Pm (peak power of the battery cell)/A (battery cell area) x Pin (incident light power per unit area)
Among them: Pin=1KW/㎡=100mW/cm ²。
2. Charging voltage
Vmax=Vrated x 1.43 times
3. Series parallel connection of battery modules
(1) The number of parallel battery modules=daily average power consumption of load (Ah)/daily average power generation of modules (Ah)
(2) Series connection number of battery modules=system operating voltage (V) x coefficient 1.43/peak operating voltage of modules (V)
4. Battery capacity
Battery capacity=average daily load electricity consumption (Ah) x continuous rainy days/maximum discharge depth
5. Average discharge rate
Average discharge rate (h)=continuous rainy days x load working time/maximum discharge depth
6. Load working time
Load working time (h)=∑ Load power x Load working time/∑ Load power
7. Battery
(1) Battery capacity=average load electricity consumption (Ah) x continuous rainy days x discharge correction factor/maximum discharge depth x low temperature correction factor
(2) Number of series connected batteries=system operating voltage/nominal battery voltage (3) Number of parallel connected batteries=total battery capacity/nominal battery capacity
8. Simple calculation based on real peak sunshine
(1) Component power=(electricity consumption power x electricity consumption time/local peak sunshine hours) x loss coefficient
Loss coefficient: take 1.6~2.0 based on local pollution level, line length, installation angle, etc
(2) Battery capacity=(electrical power x electrical time/system voltage) x continuous rainy days x system safety factor
System safety factor: take 1.6~2.0, based on battery discharge depth, winter temperature, inverter conversion efficiency, etc
9. Calculation method based on annual total radiation
Component (matrix)=Kx (operating voltage of electrical appliances x operating current of electrical appliances x time of use)/total annual radiation in the local area
When maintained by someone and in general use, K is set to 230; When unmanned maintenance+reliable use, K takes 251;
When there is no maintenance, harsh environment, and very reliable requirements, K is taken as 276
10. Calculation based on annual total radiation and slope correction coefficient
(1) Matrix power=coefficient 5618 x safety factor x total load electricity consumption/slope correction factor x annual average horizontal radiation
Coefficient 5618: Based on charging and discharging efficiency coefficient, component attenuation coefficient, etc;
Safety factor: Based on the usage environment, availability of backup power supply, and presence of personnel, take 1.1 to 1.3.
(2) Battery capacity=10 x total load electricity consumption/system operating voltage; 10 is the coefficient of no sunshine (applicable for continuous rainy days up to 5 days)
11. Multiplex load calculation based on peak sunshine hours
(1) Current: Component current=Load daily power consumption (Wh)/System DC voltage (V) x Peak sunshine hours (h) x System efficiency coefficient
System efficiency coefficient: The charging efficiency of the storage battery is 0.9, the conversion efficiency of the inverter is 0.85, and the component power attenuation+line loss+dust is 0.9. The specific adjustments will be made according to the actual situation.
(2) Power
The total power of the component=the current generated by the component x the DC voltage of the system x the coefficient 1.43. The coefficient 1.43 is the ratio of the peak operating voltage of the component to the system operating voltage.
(3) Battery capacity
Battery capacity=[load daily power consumption Wh/system DC voltage V] x [continuous rainy days/inverter efficiency x battery discharge depth]
Inverter efficiency: Between 80% and 93% depending on equipment selection; Battery discharge depth: Between 50% and 75% depending on performance parameters and reliability requirements.
12. Calculation method based on peak sunshine hours and the number of days between two rainy and cloudy days
(1) Calculation of System Battery Capacity
Battery capacity (Ah)=Safety frequency x Average daily power consumption under load (Ah) x Maximum continuous rainy days x Low temperature correction factor/Maximum discharge depth coefficient of the battery
Safety factor: between 1.1 and 1.4: Low temperature correction factor: 1.0 for temperatures above 0 ℃, 1.1 for temperatures above -10 ℃, and 1.2 for temperatures above -20 ℃; The maximum discharge depth coefficient of the battery: 0.5 for shallow cycles, 0.75 for deep cycles, and 0.85 for alkaline nickel cadmium batteries.
(2) Number of components in series
Component series connection number=system operating voltage (V) x coefficient 1.43/selected component peak operating voltage (V)
(3) Calculation of average daily power generation of components
The daily average power generation of the component=(Ah)=peak working current of the selected component (A) x peak sunshine hours (h) x slope correction coefficient x component attenuation loss coefficient. The peak sunshine hours and slope correction coefficient are the actual data of the system installation location. The component attenuation loss correction coefficient mainly refers to the losses caused by component combination, component power attenuation, component dust coverage, charging efficiency, etc., and is generally taken as 0.8.
(4) Calculation of battery capacity to be replenished for the shortest interval between two consecutive rainy and cloudy days
Supplementary battery capacity (Ah)=Safety factor x Average daily power consumption under load (Ah) x Calculation of the number of components connected in parallel for maximum continuous rainy days:
Number of parallel components=[supplementary battery capacity+average daily power consumption of load x shortest interval days]/average daily power generation of components x shortest interval days
Average daily power consumption of load=load power/load working voltage x number of working hours per day
13. Calculation of photovoltaic array power generation
Annual power generation=(kWh)=Local annual total radiation energy (KWH/m)
X photovoltaic array area (㎡) x component conversion efficiency x correction factor. P=H · A · n · K correction coefficient K=K1 · K2 · K3 · K4 · K5
The attenuation coefficient of K1 component during long-term operation, taken as 0.8;
K2 correction for component power decrease caused by dust obstruction and temperature increase, with a value of 0.82; K3 is the line correction, taken as 0.95;
K4 is the inverter efficiency, taken as 0.85 or based on manufacturer data;
K5 is the correction coefficient for the orientation and tilt angle of the photovoltaic array, taken as around 0.9.
14. Calculate the area of the photovoltaic array based on the power consumption of the load
PV module array area=annual power consumption/local annual total radiation energy x module conversion efficiency x correction coefficient A=P/H · n · K
15. Conversion of solar radiation energy
1 cal=4.1868 joules (J)=1.16278 milliwatt hours (mWh) 1 kWh=3.6 megajoules (MJ)
1 kWh/㎡ (KWh/m)=3.6 megajoules/m (MJ/m)=0.36 kilojoules/cm (KJ/cm) 100 milliwatt hours/cm (mWh/cm)=85.98 calories/cm (cal/cm) 1 megajoules/m (MJ/m)=23.889 calories/cm (cal/cm)=27.8 milliwatt hours/cm (mWh/cm)
When the unit of radiation is calories/centimeter: annual peak sunshine hours=radiation amount x 0.0116; when the unit of radiation amount is megajoules/meter: annual peak sunshine hours=radiation amount ÷ 3.6; when the unit of radiation amount is kilowatt hours/meter: peak sunshine hours=radiation amount ÷ 365 days; when the unit of radiation amount is dry joules/centimeter: peak sunshine hours=radiation amount ÷ 0.36 (0.0116, 3.6, 365,)
16. Battery selection
Battery capacity ≥ 5hx inverter power/rated voltage of battery pack
17. Electricity price calculation formula
(1) Power generation cost price=total cost ÷ total power generation
Power station profit=(purchase price - generation cost price) x working time within the service life of the power station
(2) Power generation cost price=(total cost - total subsidy) ÷ total power generation
Power station profit=(purchase price - generation cost price 2) x working time within the service life of the power station
Power station profit=(purchase price - generation cost price 2) x working time within the service life of the power station+non market factor profit
18. Calculation of return on investment
(1) No subsidy: annual power generation x electricity price ÷ total investment cost x 100%=annual return rate
(2) Subsidies for power stations: annual power generation x electricity price ÷ (total investment cost - total subsidy amount) x 100%=annual return rate
(3) Electricity price subsidy and power station subsidy: Annual power generation x (electricity price+subsidy electricity price) ÷ (total investment cost - total subsidy amount) x100%=annual return rate
19. Photovoltaic array tilt angle and azimuth angle
(1) Inclination angle
Latitude component horizontal inclination angle
0 ° -25 ° inclination=latitude
26 ° -40 ° inclination=latitude+5 ° -10 °
(In most regions of our country,+7 ° is adopted)
41 ° -55 ° inclination angle=latitude+10 ° -15 °
Latitude>55 ° Dip angle=Latitude+15 ° -20 °
(2) Azimuth angle
Azimuth angle=[peak load moment of the day (24-hour system) -12] x15+(longitude -116)
20. The spacing between the front and rear rows of the photovoltaic array
D=0.707H/tan [acrsin (0.648cos) Φ- 0.399sin Φ) ]
D: The distance between the front and back of the component array
Ф: The latitude of the photovoltaic system (positive in the northern hemisphere and negative in the southern hemisphere)
H: Vertical height from the bottom edge of the rear photovoltaic module to the top edge of the front cover
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