Calculation formula for solar panel and battery configuration - SHIELDEN

Calculation formula for solar panel and battery configuration

Solar panel and battery configuration formula 1: first calculate the current: such as: 12V battery system; 30W lights 2, a total of 60 watts. Current = 60W ÷ 12V = 5A

Calculate the battery capacity requirements:

Such as: street lamps each night cumulative lighting time needs to be full load 7 hours (h);.

(such as 8:00 p.m. to open, night 11:30 off 1 road, 4:30 a.m. to open 2 roads, 5:30 a.m. to close) need to meet the lighting needs of 5 days of continuous rainy days. (5 days plus the night before the rainy day lighting, counting 6 days) Battery = 5A × 7h × (5 +1) days = 5A × 42h = 210AH

In addition, in order to prevent overcharging and overdischarging of batteries, batteries are generally charged to about 90%; discharge residual about 20%. So 210AH is only about 70% of the real standard in the application.

Calculate the peak demand for battery panels (WP): street lamps need to be 7 hours of cumulative illumination time per night (h).

★: the average daily panel to receive effective light time of 4.5 hours (h); at least 20% relaxation of the panel needs to be set aside. WP÷17.4V=(5A×7h×120%)÷4.5h WP÷17.4V=9.33 WP=162(W)

Calculation method of photovoltaic power generation system

Photovoltaic system size and application forms vary, such as the system size spanning a wide range, as small as a few watts of solar garden lights, up to MW-level solar photovoltaic power plants. Its application forms are also varied, and can be widely used in many fields such as household, transportation, communication, and space applications. Although the size of the photovoltaic system varies, but its composition structure and working principle is basically the same.

Solar power generation system consists of a solar cell group, solar controller, storage battery (group). If the output power supply for AC 220V or 110V, you also need to configure the inverter. The role of each part is:

(i) solar panel: the solar panel is the core part of the solar power system, but also the most valuable part of the solar power system. Its role is to convert the radiant power of the sun into electrical energy, either to be sent to the battery for storage or to drive the load.

(ii) solar controller: the role of the solar controller is to control the working status of the entire system, and the battery to play the role of overcharge protection, over-discharge protection. In places with large temperature differences, qualified controllers should also have the function of temperature compensation. Other additional features such as light control switch, time control switch should be optional controller.

(c) battery: generally lead-acid batteries, small micro-systems, can also be used in nickel-metal hydride batteries, nickel-cadmium batteries or lithium batteries. Its role is to have light when the solar panel will be issued by the solar energy storage, to the time of need and then released.

(iv) Inverter: In many occasions, it is necessary to provide 220VAC, 110VAC AC power supply. Since the direct output of solar energy is generally 12VDC, 24VDC, 48VDC, in order to be able to provide electrical energy to 220VAC appliances, it is necessary to convert the DC power generated by the solar power generation system into AC power, so it is necessary to use a DC-AC inverter. On some occasions, DC-DC inverters are also used when loads of multiple voltages are required, such as converting 24VDC power to 5VDC power (note that this is not a simple step-down). The design of a PV system consists of two aspects: capacity design and hardware design.

Before the design of the photovoltaic system, you need to understand and obtain some of the basic data necessary to carry out the calculations and selection: photovoltaic system site geographic location, including the location, latitude, longitude and elevation; the region's meteorological data, including the total solar radiation month by month, the amount of direct radiation, as well as the amount of scattered radiation, the average annual temperature and the highest and lowest temperature, the longest number of consecutive cloudy and rainy days, the maximum wind speed, as well as hail, snowfall and other special meteorological conditions.

The design of the battery includes the design and calculation of the battery capacity and the series and parallel connection design of the battery pack. Firstly, the basic method of calculating battery capacity is given.

I. The first step is to multiply the daily power consumption of the load by the number of days of self-sufficiency determined according to the actual situation to get the preliminary battery capacity.

II. In the second step, the battery capacity obtained in the first step is multiplied by the maximum permissible depth of discharge of the battery. Since the battery cannot be allowed to discharge completely in the self-supply days, it is necessary to divide by the maximum discharge depth to obtain the required battery capacity. The selection of the maximum depth of discharge needs to be made with reference to the performance parameters of the battery selected for use in the PV system, and detailed information on the maximum depth of discharge of this battery can be obtained from the battery supplier. Under normal circumstances, if the use of deep-cycle batteries, the recommended use of 80% depth of discharge (DOD); if the use of shallow-cycle batteries, it is recommended that the use of 50% DOD. design of the battery capacity of the basic formula is shown below:

Days of self-sufficiency × average daily load

Battery capacity = - Maximum depth of discharge These are of course not corrected, the following is the correct formula: Battery capacity BC formula: BC = A × QL × NL × TO/CCAh (1)

Where: A is the safety factor, take 1.1 ~ 1.4;.

QL is the average daily power consumption of the load, for the operating current multiplied by the number of hours of daily operation; NL is the longest continuous rainy days; TO is the temperature correction factor, generally multiplied by the number of hours of work.

TO for the temperature correction factor, generally above 0 ℃ to take 1, -10 ℃ above to take 1.1, -10 ℃ below to take 1.2; CC for the depth of discharge of the battery, generally lead-acid batteries take 0.75, alkaline nickel-cadmium batteries take 0.85.

Below we introduce the method of determining the series-parallel connection of the battery. Each battery has its nominal voltage. In order to achieve the nominal voltage of the load, we connect a series power supply to the load with the number of batteries in series = nominal voltage of the load ÷ nominal voltage of the batteries.

Nominal load voltage

Number of series-connected batteries = nominal battery voltage

The basic idea behind the design of a solar battery is to meet the annual average daily load power requirements. The basic method of calculating solar modules is to use the average daily energy required by the load (ampere hours) ÷ the energy that a solar module can produce in a day (ampere hours), thus calculating the number of solar modules that need to be connected in parallel in the system, and utilizing these solar modules connected in parallel in the system to produce the current required by the system load. Using the rated voltage of the system ÷ the rated voltage of the solar modules, the number of solar modules that need to be connected in series can be calculated, and utilizing these solar modules connected in series can generate the voltage required by the system load.

The basic calculation formula is as follows: Number of components connected in parallel = Average daily load (AH) / Component daily output (AH) Number of components connected in series = System voltage (V) / Component voltage

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