Why is PV calculated by watt instead of area?

· About Solar Panels,PV Technology News

With the promotion of the PV industry, many people have installed PVs on their roofs, but why can’t the installation of rooftop PV power stations be calculated by area? How much do you know about various types of PV power generation? Why can't the installation of rooftop PV power stations be calculated by area?

PV power plants are calculated by wattage, which is the installed capacity, not by area. But the installed capacity is also related to the area.

There are three types of PV power generation on the market: - Amorphous silicon PV modules - Polycrystalline silicon PV modules - Monocrystalline silicon PV modules These are also the core components of PV power generation.

Amorphous Silicon PV Module

Amorphous silicon PV modules only have a maximum of 78W per square meter, and a minimum of only about 50W.

Features: large footprint, relatively fragile, low conversion efficiency, unsafe transportation, fast attenuation, but low light is better.

Polysilicon PV Module

The power per square meter of polysilicon PV modules is currently 260W, 265W, 270W, and 275W, which are more common in the market

Features: slow attenuation and long service life. Compared with monocrystalline silicon PV modules, the price has advantages, and it is also one of the more popular ones in the market.

Monocrystalline silicon PV

The common power of monocrystalline silicon PV modules in the market is 280W, 285W, 290W, and 295W, and the area is about 1.63 square meters.

Features: Compared with polysilicon with the same area, the conversion efficiency is slightly higher, and the cost is of course higher than that of polysilicon PV modules, and the service life is basically the same as that of polysilicon PV modules.

After some analysis, everyone should understand the size of various PV modules. But the installed capacity has a lot to do with the roof area. If you want to calculate how much system you can install on your roof, you must first understand what type of roof you have.

There are generally three types of roofs for installing PV power generation: color steel roofs, brick and tile structure roofs, and flat concrete roofs. The roof has a different design. The installation method for the PV power station is also different. The area of the power station being installed also varies.

Color steel tile roof

To install a PV power station on a steel structure color steel tile roof, usually only PV modules are installed on the south-facing side, and the laying ratio is 1 kilowatt covering an area of 10 square meters, which is 1 megawatt (1 megawatt = 1000 kilowatts) Number) The project needs to use an area of 10,000 square meters.

Brick roof

To install a PV power station on a brick-and-tiled roof, it is generally selected to cover the unsheltered roof area from 08:00 to 16:00 with PV modules. Although the installation method is different from that of the color steel roof, the laying ratio is similar, and it also covers an area of 1 kilowatt. About 10 square meters.

Brick roof

Flat roof

To install a PV power station on a flat roof, in order to ensure that the modules receive as much sunlight as possible, it is necessary to design an optimal horizontal inclination angle, so a certain distance is required between each row of modules to ensure that they are not blocked by the shadow of the front row of modules. Therefore, the roof area occupied by the entire project will be larger than the color steel tiles and villa roofs that can be tiled.

Flat roof

WM is megawatts.

1 megawatt = 1000000 wattage 100MW = 100000000W = 100000 kilowatts = 100,000 kilowatts A 100-megawatt unit is a 100,000-kilowatt unit. W is the unit of power, and Wp is the basic unit of power generated by batteries or power stations. It is the abbreviation of W (power), which means power generation.

From the above, MWp is the unit of megawatt (power), and KWp is the unit of kilowatt (power).

❒ PV power generation We often use W, MW, and GW to describe the installed capacity of PV power plants. The conversion relationship between them is as follows:




In our daily life, everyone is used to using "degrees" to express electricity consumption. In fact, it has a more foreign name called "kilowatt per hour (kW·h)".

Among them, the full name of "W" (W): Watt, named after the British inventor James Watt.

In 1776, James Watt created the first practical steam engine, which opened up a new era of human energy utilization and brought mankind into the "steam age". In order to commemorate this great inventor, later generations set the unit of power as "watt" (abbreviated as "watt", symbol W).

James Watt

Take daily life as an example:

One kilowatt-hour of electricity = 1 kilowatt-hour, that is, a 1 kilowatt electrical appliance is used at full capacity for 1 hour, which is exactly 1 kilowatt-hour of electricity.

The formula is: power (kilowatts) x time (hours) = degree (kilowatts per hour)

For example: a 500-watt electrical appliance in the home, such as a washing machine, is used continuously for 1 hour = 500/1000×1=0.5 degrees.

▼ Rated electric power of common household appliances:

Rated electric power of common household appliances

PV power generation Save electricity and make money

Under normal circumstances, a 1kW PV system generates an average of 3.2kW·h per day, which can be used for the operation of the following common electrical appliances:

PV power generation Save electricity and make money

The household PV power station adopts the mode of "spontaneous self-use and surplus electricity connected to the grid". After installing a household PV power station, not only can you use the electricity generated by your own PV power station, but you can also sell the unused electricity to the State Grid, making money with electricity.

PV power station

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