Why is PV calculated by (watt) instead of area?

With the promotion of photovoltaic industry, nowadays many people have installed photovoltaic on their own roofs, but why can't the installation of rooftop photovoltaic power station be calculated by area? How much do you know about the various types of photovoltaic power generation?
Installation of rooftop photovoltaic power station why can not be calculated by area?
Photovoltaic power station is calculated by watts (W), watts is the installed capacity, not according to the area to calculate. But the installed capacity and area is also related.
Because now the market of photovoltaic power generation is divided into three kinds: amorphous silicon photovoltaic modules; polycrystalline silicon photovoltaic modules; monocrystalline silicon photovoltaic modules, is also the core components of photovoltaic power generation.
Amorphous silicon photovoltaic module
Amorphous silicon photovoltaic module per square only the maximum only 78W, the smallest only about 50W.
Features: large footprint, relatively fragile, low conversion efficiency, unsafe transportation, decay more quickly, but the low light is better.

Polycrystalline silicon photovoltaic module
Polycrystalline silicon photovoltaic modules per square meter power is now more common in the market 260W, 265W, 270W, 275W
Characteristics: slow attenuation, long service life compared to monocrystalline photovoltaic module price to have an advantage, is also now more on the market a. The following chart:

Monocrystalline silicon photovoltaic
Monocrystalline silicon photovoltaic module market common power in 280W, 285W, 290W, 295W area is about 1.63 square meters.
Features: relatively than polycrystalline silicon equivalent area conversion efficiency a little higher, the cost of course, than the cost of polycrystalline silicon photovoltaic modules to higher, service life and polycrystalline silicon photovoltaic modules basically the same.

After some analysis, we should understand the size of various photovoltaic modules. But the installed capacity and the roof area is also very related, if you want to calculate their own roof can be installed how big the system, first of all, to understand their own roof belongs to which type.
There are generally three types of roofs on which photovoltaic power generation is installed: color steel roofs, brick and tile roofs, and flat concrete roofs. Roofs are different, the installation of photovoltaic power plants are different, and the area of the power plant installed is also different.

Color steel tile roof
In the steel structure of the color steel tile roof installation of photovoltaic power station, usually only in the south-facing side of the installation of photovoltaic modules, laying ratio of 1 kilowatt accounted for surface 10 square meters, that is, 1 megawatt (1 megawatt = 1,000 kilowatts) project requires the use of 10,000 square meters area.

Brick structure roof
In the brick structure roof installation of photovoltaic power station, generally will choose in 08:00-16:00 no shade roof area paved with photovoltaic modules, although the installation method is different from the color steel roof, but the laying ratio is similar, also 1 kilowatt accounted for an area of about 10 square meters.

Planar concrete roof
Installing PV power plant on a flat roof, in order to ensure that the modules receive as much sunlight as possible, the best horizontal tilt angle needs to be designed, so a certain spacing is needed between each row of modules to ensure that they are not shaded by the shadows of the previous row of modules. Therefore, the roof area occupied by the whole project will be larger than the color steel tiles and villa roofs where the modules can be laid flat.


Is it cost effective for home installation and can it be installed?
Now PV power generation project is strongly supported by the state, and gives the corresponding policy of giving subsidies for every electricity generated by the user. Specific subsidy policy please go to the local power bureau to understand.
WM, that is, megawatts.
1 MW = 1000000 watts 100MW = 100000000W = 100000 kilowatts = 100,000 kilowatts 100 MW unit is 100,000 kilowatts unit.
W (watt) is the unit of power, Wp is the basic unit of battery or power station power generation, is the abbreviation of W (power), Chinese meaning that the meaning of power generation power.
MWp is the unit of megawatt (power), KWp is the unit of kilowatt (power).

Photovoltaic power generation: We often use W, MW, GW to describe the installed capacity of PV power plants, and the conversion relationship between them is as follows.
1GW=1000MW
1MW=1000KW
1KW=1000W
In our daily life, we are accustomed to use "degree" to express the electricity consumption, but in fact it has a more elegant name of "kilowatt per hour (kW-h)".
The full name of "watt" (W) is Watt, named after the British inventor James Watt.

James Watt created the first practical steam engine in 1776, opening up a new era in the use of energy and bringing mankind into the "Age of Steam". In order to commemorate this great inventor, later people set the unit of power as "watt" (abbreviated as "watt", the symbol W).

Take our daily life as an example
One kilowatt of electricity = 1 kilowatt hour, that is, 1 kilowatt of electrical appliances used at full load for 1 hour, exactly 1 degree of electricity used.
The formula is: power (kW) x time (hours) = degrees (kW per hour)
As an example: a 500-watt appliance at home, such as a washing machine, the power for 1 hour of continuous use = 500/1000 x 1 = 0.5 degrees.
Under normal conditions, a 1kW PV system generates an average of 3.2kW-h per day to run the following commonly used appliances:
30W electric bulb for 106 hours; 50W laptop for 64 hours; 100W TV for 32 hours; 100W refrigerator for 32 hours.