Solar plants which are directly connected to the grid and can import and export energy from and to the grid are called grid-connected solar power plant. These plants are also called On-Grid Solar Power Plant.
To keep a track of various parameters of the solar plant and to act as a trusted link between consumer and the distribution company of the area, a bi-directional meter/net-meter is used which tracks all the useful parameters such as energy imported, energy exported and the net energy which is essentially the difference between imported energy and exported energy. Consumer has to pay only for the net energy. Besides these important factors, these meters also track various others parameters which provide useful information on working and status of the solar plant.
This type of solar plant arrangement should be installed by those, who live in an area well connected to the utility grid.
Huge savings in the form of subsidies, returns and Generation Based Incentives (GBI) can be met, using this arrangement of solar power plant.
Components of Grid-Connected Solar Power Plant
The major components of this arrangement are described below:
Solar panels are semiconductor devices which convert sunlight into direct-current (DC) electricity. These are connected either in series or in parallel to add up voltage and current respectively depending on the requirement/designing of the solar plant.
These are long life devices and the warranties provided by the companies are of 25 years. They may well exceed their warranty life in most cases.
Solar panels require very low maintenance as only periodic washing needs to be done. Period of washing varies from location to location but can generally be taken as once in two weeks.
Inverter is an electrical device which converts DC electricity from panels into AC electricity to be used by various appliances in homes, factories etc.
These devices have very high efficiency, generally more than 95%. Manufacturer’s generally provide a warranty of 5 years.
We use grid-tied solar inverters having a pure sine wave output.
Bi-directional meters are electric meters which are installed and tested by distribution companies in the area of installation. These are also called net-meters. They track the energy imported from the grid and the energy exported to the grid along with other vital parameters. In addition to this, bi-directional meters also track the net which is the number of units for which the consumer must pay. The net units are calculated as follows:
Net Units = (Total imported units) – (Total exported units)
These are structures on which solar panels are installed. Sometimes, inverter may also be installed on these structures by making appropriate arrangement.
We use galvanized iron (GI) structure. Galvanizing makes the structure corrosion resistant and thus, provides it a long life. Structure’s foundation is designed to cater high wind speeds.
These are wires through which different components of the solar system are connected with each other.
Two types of cables are used in solar power plants, viz., DC cables and AC cables. DC cables are used between solar panels and inverter while AC cables are used between inverter and household appliances.
Direct Current Distribution Box (DCDB)
This is a protection device connected between solar panels and inverter. It also distributes the power feed into it to subsidiary circuits. It consists of various fuses and circuit brakers for protection from the DC circuit.
Alternating Current Distribution Box (ACDB)
This is a similar protection and distribution device as DCDB but connected on the AC side of the solar plant. These also contain various MCBs or MCCBs for protection from the AC circuit.
It is a device used to protect the solar plant from the damaging effects of lightening. It consists of a high potential terminal and a ground terminal. When a lightning strikes the building on which solar plant is installed, the arrestor captures this lightening and the current from the surge is diverted through the arrestor to the earth. Thus, protecting the building.
Several earthing are done while installing a solar power plant to protect the system from occasional over-currents, short-circuits and lightening. The size and number of earthing depends on the capacity of solar plant.
The electricity generated by solar plant is firstly used in the building premises on which the plant is installed. If the consumption inside the building is less as compared to what is being generated, the excess electricity is exported to the grid. The distribution company provides various incentives for the energy exported to the grid. These incentives vary from state to state.
In case, the electricity requirement of the building is more as compared to what is being generated by the solar plant. The balance energy is imported from the grid.
In case, the energy exported to the grid is more than what is being imported; the balance will either be adjusted in the next month or the person can get incentives for the extra units generated from the distribution company. This all depends from state to state and country to country.
In any case, the consumer pays only for the net amount being shown in the bi-directional meter or the net meter.
In India, Ministry of New and Renewable Energy (MNRE) provides subsidy of 30% to the consumers who install this type of solar power plant in most states of the country. In special states, such as, Himachal Pradesh, Jammu & Kashmir, North Eastern States, Sikkim, Andaman & Nicobar Islands and Lakshadweep islands, subsidies upto 70% are also available. However, these subsidies are for residential, institutions and non-profit organisations only. For commercial and industrial customers, accelerated depreciation tax benefits of up to 80% are available.
In addition to these subsidies, different states in India provide Generation Based Incentives at different rates to promote solar energy.
Benefits of installing an On-Grid Solar Power Plant
- Reduce your electricity bill up to 100% for more than 25 years
- Solar power is a free source of energy
- Feed excess solar power to grid through net-metering, further reducing your electricity bill
- Generate approx. 1600 units of electricity per kWp annually
- Get return on investment within 4 to 5 years.
- Plant life more than 25 years
- Zero maintenance
- Get generation-based incentives (GBI)
- In India, Ministry of New and Renewable Energy (MNRE) provides subsidy of 30% to the consumers who install this type of solar power plant in most states of the country. In special states, such as, Himachal Pradesh, Jammu & Kashmir, North Eastern States, Sikkim, Andaman & Nicobar Islands and Lakshadweep islands, subsidies upto 70% are also available. However, these subsidies are for residential, institutions and non-profit organisations only. For commercial and industrial customers, accelerated depreciation tax benefits of up to 80% are available.
- No batteries are required in this system. So, no maintenance and upfront cost is required to either buy or maintain batteries.
- Get accelerated depreciation tax benefits for commercial sector
- Get 25 years warranty on solar panels and 5 years complete system warranty
- No additional/hidden costs
- Save Earth by saving tons of carbon dioxide emissions per year
- Solar panels absorb heat making your roof cooler by several degrees
- Increases property value
- Makes your building a modern green building
In comparison to thermal power plants, solar power plant can save up to 1 kilogram of carbon dioxide emissions per 1 kWh (unit) of solar power. Therefore, by these estimates, one can save up to tons of carbon dioxide emissions per year.
These savings are equivalent to planting hundreds of trees every year.
This not only prevents climate change but also helps reduce respiratory and cardiovascular health issues faced by thousands of people around the world because of increasing pollution.