Phân tích về ưu và nhược điểm của điện mặt trời mái nhà

The biggest downside of rooftop solar PV development solutions is that the electricity industry has reduced revenue, while having to be responsible for inspecting, reviewing and paying the electricity generated to the grid for the household head. However, considering the national interests, solar power will contribute to ensuring energy security (reducing the use of imported coal), protecting the environment (reducing greenhouse gas emissions) and not affecting the land use planning in localities.

Analysis of the social and economic efficiency of rooftop solar PV

A rooftop PV system (rooptop PV system) - is a system of solar panels (MT) that is installed on the roof of a building, or commercial, or residential building. Rooftop PV systems typically have much smaller capacity than terrestrial solar (PV) plants with capacity in the megawatt range. PV systems on rooftop residential buildings typically have capacities between 5 and 20 kilowatts, while systems on commercial buildings typically reach 100 kilowatts, or more.

The operation of a rooftop PV system is depicted in the figure as follows:

The DC current generated by sunlight shining on the battery tons (SOLAR PANELS) runs into the inverter (INVERTER) to convert it into alternating current (with the frequency of the current grid due to the angular control). open the thiristors of the INVERTER, in our case 50 herz), this alternating current flows into the two-way meter (METER) to be recorded and stored numerically for the latter settlement (often called the NETMETERING mechanism. ), then run into household electrical appliances (SELF USE). This process is shown on the red lines.

In case the consumer does not use up the electricity of the MT battery, the excess electricity will be transferred to the regional distribution grid (EXESS ELECTRICITY IS FED TO THE GRID). Conversely, if there is a lack of electricity (or in the absence of sunlight), the consumer must receive more from the grid (DEFICIT ELECTRICITY FROM THE GRID). The process of generating electricity to the grid, or receiving electricity from the grid, is done by gray lines and is recorded at a two-way meter for future payment.

According to the results of a preliminary assessment study by the Energy Assistance Agency - GIZ, the total economic potential of solar power projects on the ground and grid in Vietnam by 2030 is about 20,000 MW, on rooftop from 2,000 to 5,000 MW. With an average power factor of about 18% (Tmax about 1,600 hours), the exploitation of solar PV potential on the roof will increase the power system with billions of kWh per year, contributing to reducing the use of millions of tons. coal in thermal power plants - this means reducing emissions of millions of tons of greenhouse gas (CO2).

Rooftop solar cell systems have some very important advantages compared to terrestrial PV plants as follows:

1 / No land use, while terrestrial PV uses up to 1.2 to 1.3 ha for 1 megawatt (MW).

2 / Due to scattered installation on the roofs of buildings, only connect to the existing distribution grid system (mainly the low-voltage grid) of the electricity industry without having to build additional high-voltage grid from 110 kV as for terrestrial PV.

3 / Due to the connection to the regional distribution grid only, it does not affect the reliability of the power system and does not have to increase the backup source for the power system.

4 / Can easily mobilize investment capital from many different subjects (business owners, apartments, offices, individuals) in society.

The biggest downside of rooftop solar PV development solutions is that the electricity industry has reduced revenue, while having to be responsible for inspecting, reviewing and paying the electricity generated to the grid for the household head. However, considering the national interests, solar power will contribute to ensuring energy security (reducing the use of imported coal), protecting the environment (reducing greenhouse gas emissions) and not affecting the land use planning in localities ...

For rooftop PV systems, when connected to the regional grid, the following requirements must be complied with:

1 / The capacity (current) of the PV system generated to the grid must not exceed the permissible heating limit of the conductor connected from the local grid to the load households. In case of overload, there should be agreement, contract to replace the conductor with larger cross-section, or build new circuits.

2 / The PV system current generated to the grid must have a frequency of 50 hz (± error within permissible limits) and the ratio of high frequency to distortion must be within the permissible limits.

3 / Power source transmitted by PV system to the grid must have cos coefficient ≥ 0.9.

In addition, other specifications are imposed by grid requirements to make grid-connected PV systems more flexible and grid-friendly:

1 / Ensure reliable power supply.

2 / Flexible control of fair and fair capacity.

3 / Support dynamic grid according to demand; and:

5 / High efficiency, reliability, low cost and small volume./.