As the popularity of solar energy systems gradually increases, more and more people are becoming interested in solar panels, including buying solar panels, designing solar panel sizes, and DIY solar panels. In any case, the overall operation of a solar energy system is an electrical system, and in order to be able to make sure that your home’s solar panels are functioning properly or to try to do DIY solar panels, we need to learn about various related electrical knowledge, including the way to convert between various units from amps to kilowatts.
First we need to learn the following physical quantities.
1. What is an ampere (A), what is a milliampere (mA), and what is the relationship between the two?
Ampere is the unit of current (I). It expresses how much charge passes through a section of a circuit in an instant, that is, how fast the current passes through a section. Milliampere is also a unit used to measure the amount of charge flowing through a section of a circuit as well as the rate of charge flow, and its basic usage is the same as the ampere, and the conversion formula for the two is:
1A=1000mA
1mA = 0.001A
2. What is a kilowatt (kw), what is a watt (w), what is the relationship between the two?
Kilowatt is the unit of electrical efficiency (P), which is used to measure the amount of energy consumed by an appliance to complete the work. Watt is a unit similar to it, also used to measure the efficiency of electrical appliances, the conversion formula for the two:
1kw = 1000w
1w = 0.001kw
3. What is the watt-hour (Wh), what is the kilowatt-hour (KWh), what is the relationship between the two?
Watt-hour is a unit of energy (E). It is often used to measure the amount of energy consumed by an electrical appliance in the course of its work. 1Wh is defined as the amount of energy consumed by an electrical appliance with a power of 1w for 1h of work. Kilowatt-hour is the same as kWh, also a unit of energy, which is defined as the energy consumed by an appliance with a power of 1kw for 1h. The conversion formula for the two is:
1KWh = 1000Wh
1Wh = 0.001Wh
4. How to convert amperes to kilowatts？
Essentially both amps and kilowatts are units of measurement, but one is a unit of measurement of current and the other is a unit of measurement of power. In order to realize the conversion of the numerical unit from amperes to kilowatts, it is actually a formula to convert current to power. On a physical level, the conversion between two values representing different physical quantities cannot be accomplished directly. Therefore, we need to introduce another intermediate physical quantity to help in the calculation, which is the volt (v).
The volt is the unit of voltage. From a microscopic point of view, it is usually used to measure the amount of energy difference per unit electron in an electric field due to the difference in potential. And for a complete electrical system, its value is equal to the potential difference between the positive and negative poles of that electrical system.
With the introduction of volts, we can realize the conversion from amperes to kilowatts by using the following formula:
I (A) = P (kw) / 1000 x V (v)
In addition to the physical quantities that have been introduced above, the formula also contains the step of dividing the power by 1000, the main reason for this is because according to Watt’s law: the units of current, power, and volt need to be harmonized, and the unit of power that is harmonized with the ampere and the volt should be the watt, so when the numerical unit is the kilowatt, the step of dividing the power by 1000 should be added to the formula as a way of guaranteeing that the results of the calculations are correct.
After learning the formula, the following will give you an example of a practical application to help you understand the formula: when you buy a maximum discharge current of 120A lithium iron phosphate battery for your solar system, its discharge voltage between 20v-40v, then its maximum and minimum operating power are how much? According to the above amperage to kWh formula, the maximum working power of this battery is (120A x 40v) ÷ 1000 = 4.8kw, while the minimum working power is (120A x 20v) ÷ 1000 = 2.4kw.
I believe that after you have studied the above conversion formula, you already have a preliminary understanding of the amperage to kilowatt conversion formula. In fact, the above conversion formula is only applicable to DC circuits, for the more common AC circuits in practical applications, we need to use a more complex formula for conversion.
First of all, we need to know that the AC circuit is divided into single-phase AC and three-phase AC.
Single-phase alternating current
First of all, single-phase AC refers to the type of circuit that has only a single AC voltage in the circuit, and the current as well as the voltage generated in the circuit varies with time at a specific frequency.
In single-phase alternating current, the formula for realizing the conversion from amperes to kilowatts is:
P (kW) = PF × I (A) × V (V) /1000
P in the above formula refers to the power generated by the system, V refers to the RMS voltage, and since the voltage in an AC circuit varies with time, the calculation takes the RMS value of the voltage, i.e., the value of the DC voltage at which the circuit is capable of generating the same heating effect. i refers to the circuit current, and PF is the power factor of a single-phase AC circuit, i.e., a measure of the phase difference between the voltage and the current in the circuit. value. The greater the phase difference between voltage and current in a circuit, the lower the power factor, the less efficient the circuit, and the less stable the overall system.
Three-phase alternating current
Three-phase alternating current (AC) is a circuit system consisting of three alternating potentials with the same frequency, the same potential amplitude, and a phase difference of 120° from each other, and is the most commonly used type of alternating current.
For three-phase alternating current, there are two formulas for converting amperes to kilowatts:
The first is to change is to change the RMS voltage to the line-to-neutral voltage (V L-N) for calculation, with the conversion formula:
P (kW) = 3 × PF × I (A) × V L-N (V) /1000
The other is to change the RMS voltage to line-to-line voltage (V L-L) for calculation, and the conversion formula is:
P (kW) = √3 × PF × I ( A) × V L-L (V) /1000
