When moving to solar as source of electricity, grid-tied solar power system is the most favored choice in India. And there is also the idea of net metering for buyback of additional electricity produced through solar panels.
What is grid tied solar system and what is it’s relation to net metering? Can we have grid tied solar without net metering?
What is grid-tied solar system?
The term ‘grid-tied’ is also known as ‘grid connected’ or ‘on-grid’.
Grid tied solar PV system is an arrangement of your solar panel connection wherein electricity can be drawn from the traditional utility grid (main line) as well as from the solar panels. It implies, if you are installing grid-connected solar panel system at home, solar is not the only source of electricity.
How does this grid connected arrangement help solar panel users?
If you’re unable to generate enough solar electricity, then take it from the grid/main line. And if you have generated extra solar power which you cannot use, then sell it to the power grid!
Which one is the primary source of electricity out of the two?
The primary source of power is solar power plant. The loads (equipment consuming electric power) use the power generated from solar plant by default, but in case of absence of sufficient power from the solar plant, extra power can be acquired from the grid.
Who manages switching between these two sources of electricity?
The system operates automatically and switching between the supplies is so rapid that the user cannot realize any jitters in the working of their appliances.
The net meter is associated with the rooftop solar arrangement to monitor the amount of current taken and sent to the grid.
How to get grid-tied solar power system?
Hire an experienced solar power company, preferably a solar EPC company which can provide turnkey or end-to-end solar solution. It includes site survey, feasibility analysis, system design, equipment procurement, installation and even facilitating solar finance.
Grid tied solar system with net meter
A net meter is a device that records the units of electricity drawn and sent to the utility grid.
It is very much similar to the electricity meter that we have in our residences which counts the units of electricity consumed.
A net meter in solar PV arrangement can be bidirectional or unidirectional. The bidirectional net meter records both the outgoing and incoming current to the user in a same device. Otherwise, connect two unidirectional meters in parallel within the same setup; one to keep an account of incoming current and the other to record the units of electricity sent to the grid.
Electricity distribution company regulates the settlement of payment and charge as monthly rentals.
The meter records the amount of electricity imported and exported. If the imported units of electricity exceed the exported unit, then the user has to pay the amount according to the net unit consumed and as charged by the distribution company.
How does solar power feed back into the grid?
The inverter plays an important role to feed back the solar power into the grid.
The transmission lines from the grid channels the alternating current (AC). Solar panels generate direct current (DC) and the grid supply as well as appliances work on AC.
So the inverter converts the DC from the solar panels into the AC and decides to use the generated power either to run the appliances or to feed into the grid.
The excess power is fed into the grid by the principle of electrical impedance. Electrical Impedance is the measure of voltage to current ratio in an AC circuit. In other words, impedance inhibits current flow between two points in an AC electric circuit. And again the net meter installed at the user’s premises can register the amount of current flow.
Grid tied solar system without net metering: Export Limiter
The grid tied solar rooftop system can work without net-metering, where one is able to import electricity from the utility grid, but cannot send back the excess power in the grid. This is implemented by using “export limiter”, which restricts the Solar PV system to inject any excess power into the grid.
The grid tied solar system without net metering was used when the net metering facility was not available and by the lower capacity solar plant users. Well, economically this arrangement has fewer benefits as the power generated on the days when you are not using any electrical appliances goes waste.